Bulletin of the American Physical Society
2013 Fall Meeting of the APS Division of Nuclear Physics
Volume 58, Number 13
Wednesday–Saturday, October 23–26, 2013; Newport News, Virginia
Session EA: Conference Experience for Undergraduates Poster Session (2:00-4:00PM) |
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Room: Grand Ballroom II |
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EA.00001: New results for the $\beta$ decay of $^{144}$Cs into $^{144}$Ba Richard Scotten, Michael Carpenter, Shaofei Zhu The partial level structure of neutron-rich $^{144}$Ba was deduced following the $\beta$ decay of $^{144}$Cs. The number of known levels has been greatly expanded, and states with spins $\le 5 \hbar$ have been observed. The experiment was conducted using a re-accelerated beam of $^{144}$Cs extracted from CARIBU, and implanted in a Pb foil placed at the target position of the Gammasphere array. The comparative $\beta$ decay half-life, log $ft$, has been classified according to the degree of forbiddenness for 37 transitions which feed the 2$^+_1$ in $^{144}$Ba. A preliminary result of 5.94(4) favors a positive parity assignment for the $^{144}$Cs spin-1 groundstate. [Preview Abstract] |
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EA.00002: Implementation of a 256-channel aerogel RICH detector Jesse Stryker, David Blyth, Jason Holmes, Ricardo Alarcon A ring-imaging Cherenkov (RICH) detector has been constructed with the goal of testing the performance of aerogel tiles in RICH detectors. To test this, we designed a detector that can effectively identify cosmic rays in the range 0.5-2.5 GeV. Imaging is done by the proximity focusing technique, which uses multiple aerogel layers of increasing refractive index. Detection of the Cherenkov light is carried out by an array of flat-panel multi-anode PMTs, positioned along a common axis with the aerogel tiles. Effective particle separation requires low-noise, high quantum efficiency photomultiplier tubes. Four 64-channel Hamamatsu PMTs were chosen, resulting in a 16x16 (10cm x 10cm) detection grid. For each anode, the output charge is stored by its respective charge-integrator circuit. Data are acquired by means of multiplexing the signals from the PMTs. When triggering conditions are satisfied, the integrated charges from all anodes are consecutively digitized by an ADC. Using the ROOT framework, the waveforms for an event are converted into a 2-D array of pulse heights corresponding to the signal from each PMT channel. Relative pulse heights allow for subpixel resolution of the Cherenkov rings, which in turn allows for analysis of the particle and aerogel characteristics. [Preview Abstract] |
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EA.00003: Ion Source Tests for the IsoDAR Neutrino Experiment Ruben Gutierrez Martinez The Isotope Decay At Rest (IsoDAR) experiment uses a cyclotron to produce an intense electron antineutrino flux from the decay of $^8$Li at rest. It will be paired with the 1 kton Kamioka Liquid Scintillator Antineutrino Detector (KamLAND) to search for antineutrino disappearance at short base lines due to sterile neutrino oscillations. It will also be capable of making a measurement of antineutrino electron scattering. The first component of the cyclotron is an ion source that provides 5 mA of H$^+_2$ at 60 keV. The characterization of this source took place in June 2013 at Best Cyclotron Systems Inc. The first measurements from these tests will be presented. [Preview Abstract] |
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EA.00004: Multigap Resistive Plate Chamber for Fast Timing Nathaniel Lashley-Colthirst, Mickey Chiu Over the summer, I worked in a group trying to increase the time resolution of a multigap resistive plate chamber (mRPC) detector to a ten picosecond resolution, compared to the 100 picosecond resolution that is typical today. With this much better resolution, particle identification will be possible out to much higher momenta than is possible today. To improve the mRPC, we intended to produce prototypes with many more gaps than the 6 that are currently used in the PHENIX TOF.W detector, and decrease the gap size. We tested production modules from the PHENIX TOF.W using cosmic rays, and designed the new prototypes which will be constructed at a later point. [Preview Abstract] |
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EA.00005: Data Quality Analysis for PHENIX Spin Measurements Ryan Pinson At Brookhaven National Laboratory the PHENIX experiment on the Relativistic Heavy Ion Collider (RHIC) studies polarized proton-proton collisions in an effort to better understand the contribution of sea quarks to the spin structure of the proton. This is achieved by looking at the single-spin asymmetry of the W bosons created in polarized p+p interactions. To enable PHENIX to measure these contributions multiple Resistive Plate Chambers (RPCs) were integrated into both the north and south muon arms of the spectrometer and utilized as part of the forward trigger. During the 2013 RHIC Run, the RPCs were a critical component of the W trigger in part due to their excellent timing resolution. Before the W asymmetry and cross section can be determined, a careful study of the RPC high voltage status, trigger rates, and efficiencies must be completed. This systematic study of the RPC performances on a run-by-run basis has been completed and a list of these characteristics were created. While completing this initial analysis, changes in RPC performance were correlated with changes in detector conditions. Results of this first step in the analysis of the PHENIX forward W data will be presented. [Preview Abstract] |
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EA.00006: Development of a Finite State Machine and a new LabView Interface for STAR Charles Costello, Jiro Fujita The STAR (Solenoidal Tracker at RHIC) hardware controls system currently controls and monitors 60000 parameters. Although the system is has functioned for 13 years, it has been operated as 14 essentially independent subsystems with centralized error handling. A LabVIEW (Laboratory Virtual Instrument Engineering Workbench) interface and finite state machines (FSM) for two of these subsystems have been developed to overcome this situation. The EEMC (Endcap ElectroMagnetic Calorimeter) is one of these subdetectors at STAR. The EEMC is comprised of four different components that detector operators currently control and monitor separately. To integrate these subsystems, a finite state machine has been developed that would allow for centralized control and monitoring of the entire EEMC. A second subsystem, the BEMC (Barrel Electromagnetic Calorimeter) was developed using LabVIEW as a control system for testing. A new interface was developed that allows both control and monitoring of the BEMC in preparation for its inclusion in the FSM. The design and implementation of the system, as well as future plans, are discussed. [Preview Abstract] |
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EA.00007: A performance study of the micro-channel plate photomultiplier tube (MCP-PMT) Kahlil Dixon, Mickey Chiu PHENIX, the Pioneering High Energy Nuclear Interaction Experiment at Brookhaven National Laboratory (BNL), is developing particle detectors of exceptional time resolution. These world-class detectors will serve as upgrade options for future modifications to the Phenix detector, a part of BNL's Relativistic Heavy-Ion Collider (RHIC). This summer, we worked to optimize the timing resolution of the prototypes to ten picoseconds. The completed detectors will supply researchers with valuable data in the runs following installation, data that is currently in kinematically inaccessible regions. We setup the detectors in a cosmic ray test. The prototype detector I worked with is a Photonics 85012xp micro-channel-plate photomultiplier tube (MCP-PMT). Our testing setup makes use of two scintillator paddles, to trigger on the muons, and two MCP-PMT prototypes, to determine the time resolution. Currently, we are in the process of carefully analyzing the data acquired during experimentation. It will take just a little more time to study the correlations in detections between the top and bottom detectors; however, we are confident that this will be excellent option for serious consideration for installation in the Phenix detector. [Preview Abstract] |
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EA.00008: Detector response of the PHENIX Muon Piston Colorimeter for $\sqrt{S_{nn}}$=200 GeV Au+Au collisons Benjamin Kimelman Transverse energy is often used to characterize the energy density in ultra-relativistic heavy ion collisions. Most measurements are obtained in the the central rapidity region; however, the PHENIX Muon Piston Calorimeter (MPC), a homogeneous electromagnetic calorimeter, is a useful tool for measuring this quantity in the forward/backward pseudo-rapidity regions. A full Geant3 detector simulation is used for assessing detector response and the effects of particle decays on the measurement of transverse energy in the pseudo-rapidity range $3.1<|\eta|< 3.9$. In 2010, $\sqrt{S_{NN}}$=200 GeV Au+Au collisons were obtained and are being analyzed. Various event generators are used as input to the detector simulation to help determine the effects of inflow, outflow, and hadronic response of the MPC. [Preview Abstract] |
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EA.00009: W-Boson Trigger-Rate Analysis for PHENIX Andrew Miller PHENIX is the largest experiment at Brookhaven National Laboratory's Relativistic Heavy Ion Collider. One of the major goals of PHENIX is to investigate the spin structure of the proton. A primary way that PHENIX is achieving this is by measuring the single-spin W-boson asymmetry in polarized-proton collisions. The recently completed forward trigger upgrade has been specifically designed to select high transverse momentum muons that are largely from the decay of W-bosons. One important component of this trigger upgrade is the two stations of resistive plate chambers (RPCs) in each of the two muon arms. These chambers were used to collect extensive data from polarized-proton collisions for the first time during this past run. Trigger rates from this system were analyzed to determine when all components were functioning properly. Correlating changes in the trigger rates with changes in the configuration of the trigger or hardware will allow the data to be analyzed appropriately. By taking the current detector status into account, a more precise W-asymmetry measurement will be attainable. This poster will present the method and results of this analysis including trigger rates as a function of beam intensity. [Preview Abstract] |
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EA.00010: Study of the influence of neutral pion decay on the inflow and outflow of energy from the PHENIX Muon Piston Calorimeter Julian Rutkowski The PHENIX MPC is a homogeneous electromagnetic calorimeter covering a pseudorapidity range of $3.1<|\eta|< 3.9$. Transverse energy measurements with this detector must be corrected for situations in which one or both photons from neutral pion decay either miss the detector when the parent would have hit or hit the detector when the parent would have missed. This effect forms the major component of inflow/outflow corrections to measurements of transverse energy with the detector. The kinematics of these processes are studied in the UrQMD (Ultra-Relativistic Quantum Molecular Dynamics) event generator in order to understand how the geometric acceptance of the MPC will affect the measurement of transverse energy in ultra-relativistic heavy ion collisions at RHIC. [Preview Abstract] |
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EA.00011: Resistive Plate Chamber Efficiency Analysis for PHENIX Ramsey Towell The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory studies polarized proton-proton collisions to learn more about the spin structure of the proton. PHENIX's data acquisition system is able to record several thousand events each second. However, millions of collisions occur every second, so a forward trigger is required to select rare events of interest. To study the sea quark contribution to the spin structure of the proton, the interesting events are single high transverse momentum muons produced in the decay of W bosons. The muon trigger upgrade includes two sets of Resistive Plate Chambers (RPCs) in both muon arms. The recently completed RHIC run was the first extended run since the new forward trigger was fully commissioned. Initial studies indicate that the RPCs performed well and significant data was collected. Additional careful and systematic studies have been performed to determine the RPC efficiencies for each module and each run. Changes in efficiencies have been correlated to known hardware changes during the run. Results of the analyzed data showing the RPC efficiencies will be presented. [Preview Abstract] |
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EA.00012: Calibrating the PHENIX Muon Piston Calorimeter for Au+Au Collisions at $\sqrt{S_{NN}}$ = 200 GeV Cora Wallace The PHENIX Muon Piston Calorimeter (MPC) has been used extensively for p+p and d+Au collisions and,to a lesser extent, Au+Au collisions at RHIC. Progress on calibrating the MPC for measuring forward/backward transverse energy in ultra-relativistic heavy ion collisions will be reported. In particular, the status of calibrations of RHIC data taken in 2010 (in which Au+Au collisions were recorded at $\sqrt{S_{NN}}$ = 200, 62.4, 39,and 7.7 GeV) will be relayed. The approach is to follow the procedure developed in earlier p+p and d+Au analyses. Neutral pions are reconstructed from decay photons that strike the MPC.The position of reconstructed neutral pion mass peaks are compared to those expected from a perfectly calibrated detector (as determined by simulation) adjusting the gains of each calorimeter tower until the data are brought into agreement with the simulation.In the past, these calibrations have utilized the Pythia event generator to calibrate p+p and d+Au data. In the case of these heavy ion data, initially, peripheral collisions will be compared to the Pythia p+p results, but eventually, Hijing will be used to calibrate the Au+Au data. [Preview Abstract] |
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EA.00013: Comparison of UrQMD, Hijing and parameterized data as input to PHENIX detector simulations of RHIC Au+Au collisions in the forward/backward kinematic region Kathryn Kooistra A number of systematic effects must be studied in order to determine the transverse energy in RHIC $\sqrt{S_{NN}}$ = 200 GeV collisions using the PHENIX Muon Piston Calorimeter. Comparisons of the particle production in the forward/backward direction between UrQMD (Ultra-relativistic Quantum Molecular Dynamics), Hijing, and parameterizations of real data will be made to understand the influence of the choice of event generator on corrections to transverse energy measurements in the forward/backward kinematic region at RHIC. [Preview Abstract] |
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EA.00014: PHENIX Resistive Plate Chambers High Voltage Performance Analysis Marshall Towell The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory studies polarized proton-proton collisions to better understand the spin structure of the proton. While RHIC is operating there are millions of collisions each second, but the PHENIX data acquisition system can only record a few thousand each second. To help select the rare events of interest, a new forward trigger has been commissioned that includes four stations of Resistive Plate Chambers (RPCs). During the most recent RHIC run, significant polarized proton-proton data were recorded with the new trigger for the first time. The RPC high voltage was recorded and studied for each module and each run. Every physics run was classified into one of four categories depending on its high voltage conditions, including the number of trips and the number and magnitude of mismatches between the HV set point and readback voltage. Each condition that was required to consider a run to have good HV was investigated systematically to determine the appropriate set points. The methods and results of this systematic study will be presented. [Preview Abstract] |
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EA.00015: Waveform digitizing electronics for time-of-flight detectors Olivia Dickens, Mickey Chiu Cosmic rays are particles which travel through space at nearly the speed of light. When cosmic rays enter the Earth's atmosphere they collide with molecules in the air and produce charged pions; which eventually decay into muons. The experiment that I assisted with at Brookhaven National Laboratory used the muons produced from cosmic ray interactions to test the timing resolution of a cost efficient time-of-flight detector. The two detectors used were a Multigap Resistive Plate Chamber (mRPC) and a Microchannel Plate Photo Multiplier Tube (MCP- PMT). My portion of the project focused on the effect the electronics had on the timing resolution between the mRPC, MCP-PMT, and the data acquisition program for each. This was done by using a pulse generator to send signals through a cable to the wave form digitizer electronics. The timing difference between the signals was used to determine the amount of time the electronics added to the overall timing resolution of each detector. Based on the collected results, the root-mean-square value for the timing resolution was 22.89 picoseconds, which is too slow for the digitizing electronics to be used for an efficient detector. [Preview Abstract] |
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EA.00016: Particle swarm optimization of higher-order corrections to large-acceptance ion optical systems Lisa Carpenter, Matthew Amthor High-acceptance, high-resolution optical systems help to make possible the efficient study of short-lived, rare forms of nuclear matter. Preserving high resolving power with a large transmitted phase space input requires that the optical aberrations be considered and significantly corrected. The choice of higher order multipole strengths presents a challenging, many-dimensional optimization problem. Particle swarm optimization (PSO) is a global optimization technique which has shown promise in many-dimensional systems. In this computational study, PSO is applied to the higher order magnet settings of the ARIS fragment separator to be constructed at FRIB and the proposed SUPERB recoil separator. The PSO technique is expected to more quickly and reliably find global minima than techniques relying only on local optimizers. Several sets of internal PSO parameters were tested, in search of both rapid convergence and high success rates --- the likelihood that the best overall solution is found. We will present our optimal parameters and possible extensions of this work, for example creating hybrid algorithms with other optimization techniques such as differential evolution. [Preview Abstract] |
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EA.00017: Mining for $\omega$ and $\rm{f_{1}}$ decays in CLAS Data Andrew Beiter, Michael Wood One advantage of the CLAS detector at the Thomas Jefferson National Accelerator Facility (TJNAF) is its ability to reconstruct multi-particle decays. For this reason, we are mining the E02-104 data set for the exclusive decays of the $\omega$ and $\rm{f_{1}}$ mesons. Each meson has either three or four particles in the final state. Our goal is to determine the reaction rates with CLAS and extrapolate to those for the E12-06-117 experiment, that will run when the CLAS12 detector is built for the TJNAF 12-GeV upgrade. The focus of the latter experiment is to understand the hadronization process from free quarks to color-neutral hadrons. This poster will describe our work using the data mining software developed by the group at Old Dominion University under a grant from the Department of Energy. [Preview Abstract] |
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EA.00018: Development of the PCAL Reconstruction Software Craig King, Michael Wood The 12-GeV upgrade at the Thomas Jefferson National Accelerator Facility requires that the CLAS in Hall B be upgraded for the new kinematics at the higher beam energies. The new CLAS12 detector will include a component called the Pre-shower Calorimeter or PCAL. The PCAL will enhance the capabilities of the existing calorimeters and allow for greater acceptance over a wider range of momenta of particles like the neutral pion. The responsibility of the group at Canisius College is the PCAL reconstruction software. This poster will describe the software development and how it utilizes the Service-Oriented Architecture of CLAS12. [Preview Abstract] |
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EA.00019: Simulations for Kaon Absorption Studies Danielle Stewart, Michael Wood The three pieces needed to determine the $\rm{K^{0}_{s}}$ transparency ratios are the kaon yields, the target thickness, and the detector acceptance. This poster will describe our simulations for the neutral kaon acceptance by the CLAS detector for the E01-112 experiment. The experiment was conducted in Hall B at the Thomas Jefferson National Accelerator Facility for the purpose of searching for medium modifications of mesons. The reactions are the photo-production of mesons from targets of deuterium, carbon, iron, and lead. Our calculations employ the PLUTO++ software for the generator and GSIM to simulate the detector. [Preview Abstract] |
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EA.00020: The Effect of Radiation on Phaseolus vulgaris growth and Aerogel Derek Boylan, Stephanie Durham Radiation affects human life in disparately subtle and dramatic ways. For instance, nuclear reactions in the Sun produce light and heat that are essential for human existence, while recent research implies that the flux of cosmic ray particles may also have an impact on humans' daily lives. According to the EPA the average American receives 310 mrems of radiation per year, well under a total dose of 50,000 mrems and higher doses that cause symptoms ranging from nausea to death. However, scientists hypothesize that exposure to low doses of ionizing radiation ($<$ 1000 mrems) may produce beneficial effects in organisms. Thus the effect of low doses of alpha, beta, and gamma radiation (12 doses ranging from 0.04 mrems of alpha radiation to 17 mrems of gamma radiation) on Phaseolus vulgaris was tested. The same radiation was also tested on the performance of aerogel, a material used in particle detectors. Aerogel will be used in experiments at the 12 GeV Jefferson Laboratory and has been previously observed to change its optical characteristics after being used in experiments. To determine the level of cosmic ray flux and possible contribution to our experiments a detector was created using scintillator material and 2-inch phototubes. Results from our experiments will be presented. [Preview Abstract] |
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EA.00021: The Effect of Radiation on Phaseolus vulgaris and Aerogel Stephanie Durham, Derek Boylan Radiation affects human life in disparately subtle and dramatic ways. For instance, nuclear reactions in the Sun produce light and heat that are essential for human existence, while recent research implies that the flux of cosmic ray particles may also have an impact on humans' daily lives. According to the EPA the average American receives 310 mrems of radiation per year, well under a total dose of 50,000 mrems and higher doses that cause symptoms ranging from nausea to death. However, scientists hypothesize that exposure to low doses of ionizing radiation ($<$ 1000 mrems) may produce beneficial effects in organisms. Thus the effect of low doses of alpha, beta, and gamma radiation (12 doses ranging from 0.04 mrems of alpha radiation to 17 mrems of gamma radiation) on Phaseolus vulgaris was tested. The same radiation was also tested on the performance of aerogel, a material used in particle detectors. Aerogel will be used in experiments at the 12 GeV Jefferson Laboratory and has been previously observed to change its optical characteristics after being used in experiments. To determine the level of cosmic ray flux and possible contribution to our experiments a detector was created using scintillator material and 2-inch phototubes. Results from our experiments will be presented. [Preview Abstract] |
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EA.00022: Characterization of Aerogel's Optical Properties Abigail Justen, Jonathan Young Aerogel is used in the kaon aerogel Cerenkov detector at Jefferson Lab. Kaons are identified by the number of photons created through Cerenkov radiation emitted as the kaon travels through the aerogel. Depending on the refractive index of the aerogel, kaons of different momenta can be detected and distinguished from protons. Therefore, a uniform refractive index in the detector is important to reduce uncertainty in the Cerenkov radiation. We found the refractive index of the aerogel by shining a red construction laser through it and measuring how far the beam refracted. The refractive index of aerogel is also directly related to the density of aerogel. The humidity in the air, if absorbed, could also affect the refractive index. To test the effect of humidity on aerogel we used a humidity controlled environment between 80 and 100 percent on aerogel from Matsushita Electric Works, Ltd, Japan Fine Ceramic Center, and Novosibirsk. Finally, we tested the transmittance of aerogel tiles with a UV/Vis photospectrometer to find the correlation between transmittance and the tile's properties. Tiles with the highest transmittance will allow for the most accurate count of the photons produced through Cerenkov radiation. The results from these experiments will be presented. [Preview Abstract] |
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EA.00023: Efficient Amplification of Photomultiplier Signals Sergio Ribeiro, Alex Maleski Understanding hadron structure is an important goal of modern nuclear physics. Exclusive reactions with neutral final states play an important role, for instance, allowing one to probe universal features of GPDs and to verify their formalism in thus far unexplored regimes. The Jefferson Lab 12 GeV upgrade provides the energies needed for precision neutral particle cross section measurements in Hall C. A new PbWO4 spectrometer provides a simple and economical option for neutral particle ID. As particles traverse the calorimeter's 1116 PbWO4 blocks, scintillation will occur, which can be detected by 19-mm PMTs. The resulting signals are processed in a DAQ system. Depending on module resolution processing signals from these relatively small PMTs can be challenging. PMTs are sensitive enough to count single photons. However, the pulses height for single photons and double photons are often indistinguishable. The best way to conquer this problem was to amplify the PMT signal by using a solid-state amplifier. We designed and constructed an amplifier prototype comparing the amplification provided by a typical 741 op amp to a 595-THS3202D fast op amp. While both amplifiers are capable of adequate gain the 741 would be inadequate for the amplification of fast pulses from the PMTs. [Preview Abstract] |
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EA.00024: Energy Levels of Na Isotopes in and Around the Island of Inversion Scott Saenz, Kathrin Wimmer More than 35 years after its discovery, the ``Island of Inversion'' continues to be of great interest for the nuclear physics community. Determining the level scheme for radioactive isotopes in and around the ``Island of Inversion'' can lead to a better understanding of the structure of these exotic nuclei. Sodium isotopes $^{\mathrm{27}}$Na -- $^{\mathrm{30}}$Na were chosen due to their enclosure or proximity to the ``Island of Inversion.'' The experiment was conducted at the NSCL in the spring of 2013 and utilized an array of seven GRETINA detectors in conjunction with the S800 spectrograph. The high resolution and efficiency of the GRETINA array allowed for detection of previously unknown lower energy levels. Preliminary analysis of the in-beam $\gamma $-residue, $\gamma $-$\gamma $ residual coincidences and the resultant level scheme will be presented at the conference. [Preview Abstract] |
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EA.00025: Simulator for the Parity-Violating Deep Inelastic Scattering experiment in the Solenoidal Large Intensity Detector Jack Anderson The Solenoid Large Intensity Detector (SoLID) particle detector is the main detector that will be used for high energy particle experiments in Hall A that will be used with the 12 GeV electron beam at the Jefferson Lab. SoLID geometries were writen to be implemented in Geant4 using openGL as the visualization tool. This will allow us to test how the calorimeter, a specific yet integral part of the SoLID detector, detects the particles that result from electron beams colliding with targets. The goal is to simulate the approved experiments for the SoLID detector, starting with the Parity-Violating Deep Inelastic Scattering (PVDIS) experiment. This will provide critical information regarding the effectiveness of the calorimeter's design for such experiments. The expectation is that a Shashlik calorimeter will prove effective for the experiments approved for the SoLID detector. The ideal number of layers, or types of material for said layers, is an aspect of the calorimeter that will require testing through the simulations.The geometry files allow an easily-packaged program that can be shared amongst any collaborators interested in the SoLID experiments. [Preview Abstract] |
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EA.00026: Daya Bay Antineutrino Flux Calculations and Effective Weekly Reactor Data Jaclyn Lakey Within the framework of the neutrino oscillation theory the Daya Bay Reactor Neutrino Experiment has measured the $\sin^2{2\theta_{13}}$ mixing angle to be $0.089\pm 0.010(stat)\pm0.005(syst)$. The value of $\sin^{2}2\theta_{13}$ is extracted by comparing the observed spectrum with that of the predicted spectrum using chi-squared method. The predicted spectrum is based on the calculated reactor flux and the Daya Bay antineutrino detector model. Precise antineutrino flux calculations are an essential part of oscillation analysis. To ascertain the flux we need knowledge of the antineutrino energy spectra of fission isotopes, the isotopes fractional contribution, the thermal power produced and the isotope fission energies. In addition to the antineutrino flux some analyses need access to complete reactor information. We have designed a method which provides analyzers the unbiased effective weekly reactor data based upon the confidential daily reactor information. This poster will show how the Daya Bay reactor fluxes and effective weekly reactor data are calculated. [Preview Abstract] |
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EA.00027: Track Reconstruction and Determination of Kinematic Parameters for the Qweak Experiment Rachel Taverner, Wouter Deconinck The Qweak experiment at Jefferson Lab aims to make a high-precision measurement of the weak charge of the proton by examining the asymmetry in the scattering rate of left-handed and right-handed electrons from a proton target. The weak charge of the proton, $Q^p_{weak}$, is related to the scattering asymmetry and to the momentum transfer, $Q^2$. In order to determine $Q^p_{weak}$ with small uncertainty, we must measure the value of $Q^2$ precisely, as well. Monte Carlo simulations of the experiment, under different configurations and conditions, are run to determine the values of various kinematic parameters, such as $Q^2$, the scattering angle, $\theta$, and the scattered energy, $E'$. By comparing the kinematic parameters obtained from the simulation files, after track reconstruction, to the parameters obtained from the experimental data, we can determine the accuracy of the simulations and reconstruct the value of $Q^2$ at the interaction vertex. [Preview Abstract] |
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EA.00028: Analysis of GEANT4 Physics List Properties in the 12 GeV MOLLER Simulation Framework Christopher Haufe To determine the validity of new physics beyond the scope of the electroweak theory, nuclear physicists across the globe have been collaborating on future endeavors that will provide the precision needed to confirm these speculations. One of these is the MOLLER experiment - a low-energy particle experiment that will utilize the 12 GeV upgrade of Jefferson Lab's CEBAF accelerator. The motivation of this experiment is to measure the parity-violating asymmetry of scattered polarized electrons off unpolarized electrons in a liquid hydrogen target. This measurement would allow for a more precise determination of the electron's weak charge and weak mixing angle. While still in its planning stages, the MOLLER experiment requires a detailed simulation framework in order to determine how the project should be run in the future. The simulation framework for MOLLER, called ``remoll", is written in GEANT4 code. As a result, the simulation can utilize a number of GEANT4 coded physics lists that provide the simulation with a number of particle interaction constraints based off of different particle physics models. By comparing these lists with one another using the data-analysis application ROOT, the most optimal physics list for the MOLLER simulation can be determined and implemented. [Preview Abstract] |
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EA.00029: A Multidimensional Study of Hadronization in Nuclei Nathan Miles, Wouter Deconinck, Mike Kordosky At the present moment there doest not exist a universal event generator in high energy neutrino physics and this is where GENIE (Generates Events for Neutrino Interaction Experiments) is currently being implemented. The aim for GENIE is to become and extensive canonical Monte Carlo (MC) event generator for a wide range of neutrino interactions and in order to achieve this GENIE must be repeatedly verified with experimental data collected from neutrino interaction experiments conducted around the world. This paper focuses on comparing data obtained in a multidimensional study of hadronization in nuclei done by the HERMES collaboration with a reproduction of a similar experiment via GENIE. The experiment was a simulation of colliding a beam of electron neutrinos at 27.6 GeV with carbon-12 and deuterium nuclei and then observing the dependence of hadron multiplicity ratios, $R^h_A$, of carbon to deuterium for $\nu$, the energy transferred to the struck valence or sea quark by the virtual boson, and z, the fractional energy carried by the hadron produced as a result of exciting the valence or sea quark out of the nucleon. The dependence of the multiplicity ratios were analyzed for 8 different particles, $\pi^+$, $\pi^-$, $\pi^0$, $K^+$, $K^-$, $K^0$, $p^+$, and $p^-$. [Preview Abstract] |
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EA.00030: Comparing Super Kamiokande Attenuation Length to Proposed Hyper Kamiokande Detector Karl Ahrendsen The highly successful Super Kamiokande Water Cherenkov detector has a proposed big brother, Hyper Kamiokande. In order to ensure that building Hyper Kamiokande will be of benefit to the physics community, simulations must be run on the detector. These simulation will help to determine what physical events it will be sensitive to and how large the detector will be built. The attenuation of light in these detectors is of particular interest to determine how many dividing walls are necessary for the Hyper K detector. Through simulations in WCSim, a program developed from the GEANT4 framework, the attenuation of light is shown to be comparable to Super K, if not a little longer. This serves as evidence that Hyper K as it is currently designed will be an effective tool for studying neutrino physics. [Preview Abstract] |
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EA.00031: New Targets for New Accelerators Bryce Frentz, Khachatur Manukyan, Ani Aprahamian New accelerators, such as the 5MV Sta Ana accelerator at the University of Notre Dame, will produce more powerful beams up to 100's of $\mu$Amps. These accelerators require a complete rethinking of target preparation since the high intensity of such beams would melt conventional targets. Traditionally, accelerator targets are made with a tantalum backing because of its high atomic mass. However, tantalum is brittle, a poor conductor, and, if produced commercially, often contains impurities (e.g. fluorine) that produce undesirable background and reaction products. Tungsten, despite its brittle structure and poor conductivity, has a high atomic mass and lacks impurities, making it a more desirable backing. In conjunction with tungsten's properties, copper is robust and a far superior thermal conductor. We describe a new method of reactive joining that we developed for creating targets that use the advantageous properties of both tungsten and copper. This process involved placing a reactive mixture between tungsten and copper and applying a load force. The mixture is then ignited, and while under pressure, the system produces conditions to join the materials. We present our investigation to optimize the process of reactive joining, as well as some of the final target's properties. [Preview Abstract] |
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EA.00032: Monte Carlo simulation of a photodisintegration of $^{3}H$ experiment in Geant4 Isaiah Gray An upcoming experiment involving photodisintegration of $^{3}H$ at the High Intensity Gamma-Ray Source facility at Duke University [1] has been simulated in the software package Geant4. CAD models of silicon detectors and wire chambers were imported from Autodesk Inventor using the program FastRad and the Geant4 GDML importer. Sensitive detectors were associated with the appropriate logical volumes in the exported GDML file so that changes in detector geometry will be easily manifested in the simulation. Probability distribution functions for the energy and direction of outgoing protons were generated using numerical tables from previous theory [1], and energies and directions were sampled from these distributions using a rejection sampling algorithm. The simulation will be a useful tool to optimize detector geometry, estimate background rates, and test data analysis algorithms. \\[4pt] [1] C.R. Howell, Differential Cross-Section Measurements of Two- and Three- body Photodisintegration of the Triton and Search for a Bound Dineutron State: A New Proposal to the High Intensity Gamma-Ray Source (HI$\gamma$S). [Conference] HI$\gamma$S-PAC (June 2013). [Preview Abstract] |
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EA.00033: (Gamma,n) Polarization Asymmetry Ratios of 209-Bismuth David Payette There has been an ongoing research program measuring the polarization asymmetries from the $(\gamma,n)$ reaction on various nuclei using linearly and circularly polarized gamma-ray beams from the High Intensity Gamma Ray Source (HI$\gamma$S) at Duke University. Experimental results will be shown for $(\gamma,n)$ polarization asymmetry ratios on $^{209}Bi$ for neutron energies from $2-7$ MeV, and for angles $55^{\circ},90^{\circ},125^{\circ},72^{\circ},$ and $107^{\circ}$. Measurements were taken using linearly polarized gamma ray beam energies from $11-15.5$ MeV and circularly polarized at $15.5$ MeV, and 16 liquid scintillator detectors, half in the plane of polarization, and half perpendicular. Results demonstrate that Giant Dipole Resonance causes isotropic ratios at lower neutron energies (2-4 MeV), and non-isotropic ratios at higher neutron energies (5-7 MeV). This research introduces the possibility of using $(\gamma,n)$ as a method for identifying materials crossing international borders, by knowing ratios of many different metals. [Preview Abstract] |
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EA.00034: Neutral-Current Supernova Neutrino Interactions in Liquid Argon Benjamin Suh We have investigated a new neutral-current $\nu-^{40}$Ar channel for interaction of supernova neutrinos in liquid $^{40}$Ar. We used the default smearing assumptions and the ar17kt detector configuration in SNOwGLoBES, an event rate calculator, to determine the expected number of events. For this analysis, the ``Livermore'' supernova flux and cross-section calculated by Dr. Anna Hayes were used. We found that there is a sizeable peak at this energy, which shows that this interaction will be easily measureable, and thus allow the total supernova neutrino flux to be calculated. In the future, we hope to improve the accuracy of our energy resolution algorithm since it might have been too optimistic, and we hope to use this data in full detector simulations to determine what effect this research will have in practice. [Preview Abstract] |
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EA.00035: TBD Kyle Bowling |
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EA.00036: Improvement of Environmental Monitoring for the SeaQuest Detector Elizabeth Carlisle SeaQuest (E906), is a fixed target experiment at Fermilab that uses the Drell-Yan process to measure the anti-down to anti-up quark asymmetry in the nucleon sea. Recording environmental conditions is important for a particle physics detector, since detector performance and response can vary depending on conditions such as temperature and pressure. SeaQuest uses many drift chambers, and monitoring their performance can be aided by having these environmental measurements. Due to the size of the detector hall, there are vertical temperature gradients, so temperature must be measured at varying heights. Another important need is to monitor temperature in electronics racks to know when they are overheating. The requirements of the equipment to be used were that it had to be ethernet based and rely only on non-proprietary software. Also, in order to be used during a data run, it had to be fast enough to be recorded between beam spills. This poster will focus on our solution for measuring environmental conditions, such as decreasing the sensor readout from 17.5 seconds to 6.9 seconds. [Preview Abstract] |
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EA.00037: Hephaestus: Hardware Control for SeaQuest Trigger and Tracking Systems Ryan Castillo E906/SeaQuest is a fixed-target Drell-Yan experiment using Fermilab's 120 GeV Main Injector to measure cross sections for dimuon production in p$+$p and p$+$A collisions over a wide Bjorken-x range. Data from these collisions will be used to measure the d-bar/u-bar asymmetry in the proton sea, clarify the nature of parton energy loss in cold nuclear medium, and explore the shadowing/anti-shadowing effects observed by the European Muon Collaboration (EMC). In order to streamline operations, a hardware control program was developed for our hodoscope high voltage (HV) supply and level shifter boards (LSB), which control the front-end electronics for our wire chambers. This program has several advantages over the current software, including full integration into SeaQuest's software framework and a user-friendly command syntax. This presentation will focus on SeaQuest's physics motivations, as well as the motivation for and prominent features of the hardware control program, Hephaestus. [Preview Abstract] |
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EA.00038: Signal-width Analysis of the E-906/SeaQuest Hodoscope Data Noah Kitts SeaQuest, Fermilab E906, is a fixed target experiment that measures the Drell-Yan cross-section ratio of proton-proton to proton-deuterium collisions in order to extract the sea anti-quark structure of the proton. SeaQuest will extend the measurements made by E866/NuSea with greater precision at higher Bjorken-x. The SeaQuest detector has 8 hodoscope arrays which are used as input for the primary trigger. SeaQuest receives a proton beam extracted from Fermilab's Main Injector with a RF structure of 19 ns. According to the hodoscope setup, signals with a width of 10 ns to 15 ns have been expected. During the commissioning run in 2012 signals much longer than the expected signal width were observed. Data are analyzed in order to investigate the source of these signals. Through plotting the signal width versus the number of counts in each station and at individual hodoscopes, it is clear these long signals are more abundant in Station 1, more specifically towards the center where the beam is located. This presentation will focus on the analysis of these long signal pulses. [Preview Abstract] |
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EA.00039: A pp Collider in a 100 km Ring at Fermilab [VLHC] M. Karl Medina Recent discovery of a Higgs-like boson at CERN has reignited interest in a future high energy collider to study physics beyond the Standard Model of elementary particle physics. We propose a proton-proton (pp) Very Large Hadron Collider (VLHC) with collision energies of $\sim$ 100 TeV.\footnote{\textit{Proton-proton and electron-positron collider in a 100 km ring at Fermilab}, C.M. Bhat, P.C. Bhat, W. Chou, E. Gianfelice-Wendt, J. Lykken, G.L. Sabbi, T. Sen, R. Talman, arXiv:1306.2369 [physics.acc-ph].} A Java-based tool for studying the parameters of such a collider has been developed. The dynamics of the protons in this high energy range is dominated by the effects of synchrotron radiation. We model the effects of radiation damping and intra-beam scattering on quantities such as the emittance and luminosity. Our model shows that integrated luminosities near 1 fb$^{-1}$ can be obtained over a 10 hour luminosity store. Here we present details of the program and some key results from our study of the proposed collider. [Preview Abstract] |
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EA.00040: Timing Improvements of SeaQuest Hodoscope System Lacey Medlock Experiment 906, SeaQuest, at Fermi National Accelerator Laboratory is a fixed-target experiment studying muon pairs produced through Drell-Yan scattering. The main goal is to determine the anti-down to anti-up quark asymmetry in the nucleon sea at a higher Bjorken-x than its predecessor, E866/NuSea. The SeaQuest detector relies on hodoscope arrays for its fast trigger. The signal pulses received from the hodoscopes last approximately 20 ns, which is an issue because the proton spills occur over a 1 ns period every 19 ns. These long pulses impact our ability to determine which proton spill produced the event. In order to reduce the pulse length to reach single spill resolution, 5 ns clip lines have been added to reflect part of the PMT signal, canceling out the long tail and shortening the pulses from the hodoscopes by a factor of two. This presentation will focus on improvements made to the trigger timing by the use of clip lines. [Preview Abstract] |
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EA.00041: Target/Dump Identification for Dimuon Vertices at Fermilab E906/SeaQuest Catherine Culkin, Joshua Rubin, Christine Aidala The SeaQuest collaboration at Fermilab measures the Drell-Yan process in order to determine the light flavor asymmetry of antiquarks in the nucleon sea. SeaQuest uses the 120 GeV proton beam from the Fermilab Main Injector on targets of liquid hydrogen and deuterium. The Drell-Yan process produces muon pairs in the target as well as in the solid iron beam dump. Using the SeaQuest reconstruction program, tracks are traced upstream through the dump iron and paired to form dimuons, but the multiple scattering of muons in the dump limits the spatial and mass resolution of the reconstructed muon pairs. Cuts need to be optimized on the Monte-Carlo data to best resolve the origins of the muon pairs. This allows target events to be separated from dump events. These cuts have been applied to actual data from the commissioning run (2012) and will be applied to the two-year production run, scheduled to begin in late October of this year. The current status for the simulations and analysis will be presented. [Preview Abstract] |
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EA.00042: Effective R-matrix parameters of the Woods-Saxon nuclear potential Dylan Abrahamsen, Alexander Volya, Ingo Wiedenh\"over The phenomenological R-matrix approach is one of the most practical tools for the analysis of the multi-channel resonant scattering data. However, the relatively unconstrained phenomenological parameters of the R-matrix approach have been subjects of a continuous criticism. goal of this research is to study the connection between the R-matrix channel radius and the reduced width and the parameters of the actual potential model. We evaluate the scattering observables of the Woods-Saxon potential [1] and do an R-matrix fit which allows for the reduced width and channel radius to be determined. The dependence of the R-matrix parameters on the diffuseness, spin-orbit interaction and on other parameters of the nuclear potential is discussed. Work is supported by the~US Department of Energy under Grant No. DE-FG02-92ER40750 and by the NSF.\\[4pt] [1] http://arxiv.org/abs/0706.1628 [Preview Abstract] |
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EA.00043: Search for d3/2 single particle strength in 15N in Unbound Levels C.E. Mertin, D.D. Caussyn, A.M. Crisp, N. Keeley, K.W. Kemper, O. Momotyuk, B.T. Roeder, A. Volya The population of states in the nucleus 15N provides the opportunity to investigate both single particle and cluster structures in the 1p and 2s1d shells. Single, two, three and four particle transfer reactions selectively excite states in 15N thus providing a way to explore current nuclear structure models. Narrow structures are observed in the various transfer reactions up to at least 20 MeV in excitation well above the neutron (10.8 MeV) and proton (10.2 MeV) separation energies. In the present work new results for the reaction 14N(d,p) are presented that explore possible single particle strengths up to 18 MeV in excitation. The beam energies used in the present work were between 10.5 and 16 MeV. An early work with a beam energy of 8 MeV clearly populated strong sharp levels at 10.07 and 11.23 MeV and the present work confirms their existence. In addition, very weak broader levels are populated at 12.13 and 12.5 MeV but no other structures are found experimentally at higher excitation energies. The results of shell model calculations that include the 1p and 2s1d shells will be presented. The centroid energies for the 1d5/2 and 2s1/2 single particle strength have been obtained through comparison with FRESCO calculations. [Preview Abstract] |
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EA.00044: Development of a Cost-Effective Cosmic Ray Neutron Detector Matthew Haddad Recent studies indicate that there is a strong correlation between the cloud coverage in the atmosphere and the neutron flux measured at the surface of the Earth (Marsh {\&} Svensmark, 2000). A project at Georgia State University (GSU) is to develop cost-effective portable cosmic ray detectors which will simultaneously measure cosmic muon and neutron flux in order to study the long-term correlation between climate change and the cosmic ray flux variation. This talk will present a prototype Geiger tube-like detector we are currently developing at GSU for measuring neutrons. [Preview Abstract] |
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EA.00045: Structure of Neutron Star Crusts Christian Briggs, Chuck Horowitz, Thomas Dombroski Very dense matter in neutron star crust forms a crystal wherein columbic repulsion of the nuclei is the dominant force. To characterize this lattice, we calculate radial distribution functions, g(r), and static structure factors, S(q), from large scale molecular dynamics (MD) simulations. Our simulations consist of 27,648 nuclei modeled classically in a periodically bounded cube. With differing thermal energy and nucleus identity, lattice defects are present with non-constant frequency. This is quantified by a radial distribution function, g(r), which models the probability of finding another nucleus any distance ``r'' away. This function allows for a quick order $\sim$ N$^{2}$ calculation of the crystal defects. Discrete inter-ion distances of g(r) with large magnitude correspond to permutations of the lattice constant, while their delta function resemblance corresponds to the perfection of the crystal. S(q) is another metric used to quantify the structure of the crystal lattice. We perform this calculation in two ways, the first by Fourier transforming g(r) and the second by scattering each q vector over the crystal. The first allows the calculation of high-q values, giving a macroscopic understanding of the system. The second, while computationally intensive, yields a better resolution, especially at low-q. From s(q) we can calculate the thermal and electrical conductivity of neutron star crust. This information is crucial in understanding neutron star cooling as well as interpretation of other observables. [Preview Abstract] |
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EA.00046: Measuring Underground Neutron Fluxes for Neutrinoless Double Beta Decay Katrina Colletti, Rex Tayloe, Robert Cooper, Lance Garrison, Tyler Thornton, Ethan Steele The goal of this project was to measure the muon-induced neutron flux in lead at sea level using the SciBath neutral particle detector. The muon-induced neutron rate is not well known, is challenging to measure and simulate, and potentially an important background for underground experiments such as the EXO neutrinoless double beta-decay experiment. A mass of 45 kg of lead was placed on top of the detector, and muon/neutron-capture correlated events were measured. Events with accidental neutron-capture signals were subtracted as were muon/neutron-capture correlated events from spallation in the detector liquid scintillator. This procedure resulted in a neutron yield from lead at sea level of \(1.4 \,(\pm1.1)\times10^{-5}\frac{\mathrm{n}}{\mu}{\,(\mathrm{g cm}^{-2})}^{-1}\) with the typical muon energy at sea level \(E_{\mu}\approx4 \mathrm{GeV}\). We compare this to parameterizations created for underground experimental sites extrapolated up to sea level. [Preview Abstract] |
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EA.00047: Geometry Optimization in NOvA with Geant4 Vivan Nguyen, Mark Messier NOvA is a neutrino beam experiment, designed to detect neutrino oscillations. There are two detectors, placed at distances of 1km and 810 km from the proton target. The detectors are made of PVC filled with liquid scintillator. In simulating the experiment, an important aspect is the detector geometry, which is input to Geant4 using the GDML markup language. I will present studies in which the geometry description was systematically varied to find a configuration which preserved the modeling accuracy required by the experiment while minimizing the CPU time required for the simulation. [Preview Abstract] |
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EA.00048: One-Proton Breakup of $^{18}$F and the $^{17}$O(p,$\gamma )^{18}$F Reaction in Classical Novae Bryan Isherwood, A. Banu Classical nova studies are of considerable interest for understanding the chemical evolution of the Galaxy. They have been proposed as the most significant source for the nucleosynthesis of the isotopes $^{13}$C, $^{15}$N, and $^{17}$O in the Universe. Novae are also likely to synthesize the short-lived radioisotope $^{18}$F (T$_{1/2}=$ 110 min), which is expected to be the most important contributor to the observed emission of 511 keV gamma radiation by space-based $\gamma $-ray telescopes. This emission is produced by electron-positron annihilation following the beta$+$ decay of radioactive nuclei. A detection of these gamma rays could significantly constrain the nova simulation models. $^{18}$F nucleosynthesis in classical novae strongly depends on the thermonuclear rate of the $^{17}$O(p,$\gamma)^{18}$F reaction, which is part of the CNO cycle. This work presents preliminary results toward determination of the $^{17}$O(p,$\gamma )^{18}$F reaction cross section, which was measured by the indirect method of one-proton nuclear breakup at intermediate energies. The experiment was carried out at GANIL using a beam of $^{18}$F at 40 MeV/u impinging on a carbon target. Longitudinal momentum distributions of the $^{17}$O breakup fragments were measured in coincidence with $\gamma $-rays emitted by $^{17}$O residues. [Preview Abstract] |
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EA.00049: Studying the ($\alpha $,p) process in X-ray bursts using rare isotope ion beams Daniel Votaw, Adriana Banu, B.T. Roeder, G.G. Rapisarda, M. McCleskey, A. Saastamoinen, E. Simmons, A. Spiridon, L. Trache, R.E. Tribble, C.A. Gagliardi Type I X-Ray bursts are the most frequent thermonuclear explosions observed in the galaxy with about 100 sources known so far. It is thought that XRBs occur in binary star systems where a neutron star accretes matter from its companion, a main sequence star. As the accreted hydrogen-and helium-rich matter builds up on the surface of the neutron star the temperature and the pressure increase and a thermonuclear runaway occurs reaching peak temperatures of T $=$ 1-2 GK, which is observed as an X-ray burst. The fact that the bursts do not destroy the binary star system makes X-ray binaries useful to study matter under extreme temperature and density conditions. Current sensitivity studies on XRB nucleosynthesis have identified the nuclear reaction, $^{22}$Mg($\alpha $,p)$^{25}$Al, among the influential reactions affecting the XRB total energy output. This reaction implies the interaction of the radioactive $^{22}$Mg isotope with a~$^{4}$He nucleus (aka $\alpha $ particle) to produce the radioactive $^{25}$Al isotope and a proton. In fall last year, a feasibility test for the experimental investigation of the probability of this nuclear reaction to occur was performed at Texas A{\&}M University (TAMU) Cyclotron Institute. Measurements were performed in reversed time and inverse-kinematics for the reaction, $^{\mathrm{25}}$Al $+$ p $\to$ $^{22}$Mg $+ \alpha $. Data analysis results will be reported. [Preview Abstract] |
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EA.00050: The Classical Limit of the Nuclear Symmetry Energy Rodolfo Gonzalez, Jorge Lopez, Enrique Ramirez-Homs This talk will report on the study of the symmetry energy of infinite nuclear matter using classical molecular dynamics. Through simulations of infinite nuclear matter systems at different temperatures, densities and isospin content, fits to the equation of state can be obtained and used to extract the symmetry energy of nuclear matter. Preliminary results indicate that matter with high isospin asymmetry (Z/A=0.3) have extremely low saturation densities and probably cannot exhibit a transition from a liquid to a gaseous phase. The symmetry energy found appears to be independent of the temperature, and it compares satisfactorily to previous calculations. [Preview Abstract] |
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EA.00051: Analysis of the BRAN Forward High Luminosity Detectors at the LHC Brett Green, Alessandro Ratti, Howard Matis The Beam Rate of Neutrals detectors measure relative luminosity in the far forward regions of ATLAS and CMS at the LHC by detecting secondary showers from neutral particles using high-pressure ionization chambers. One detector is on each side, clockwise and counterclockwise, of ATLAS and CMS. Proton-proton, proton-lead, and lead-lead collisions have been measured. We have simulated the detector during all three collision types (pp, pPb, and PbPb) in the modeling program FLUKA. The detectors take measurements in both pulse height and counting modes for four separate quadrants. Pulse height mode measures changes in voltage caused by incoming particles, whereas counting mode measures the number of times a threshold was exceeded. We show that the detector can measure luminosity for all reaction types on both sides, a range extending over three orders of magnitude. We calculate crossing angle, and we quantify reaction asymmetry. We show that by comparing data with known and accepted values we may calibrate the detector. [Preview Abstract] |
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EA.00052: Strangeness Production in Jets with ALICE at the LHC Micheal Tyler II, Rodney Carmona, Austin Harton, Edmundo Garcia, Ron Soltz The study of strangeness production is integral to understanding high energy relativistic heavy ion collisions. The measurement of production yields and particle ratios, dominated by the low energy region of the spectra, helps to understand the properties of the QCD medium created during the collisions. The baryon over meson ratio at intermediate pT allows the study of hadronization taking place as the medium evolves. Furthermore, the study of strange particles in collisions provides information on parton fragmentation, a fundamental QCD process. To establish a baseline, measurements are first performed in proton-proton (pp) data. However, the role of high-momentum observables is equally important to understanding QCD matter. Low- and mid-pT strangeness measurements are already in progress at RHIC and the LHC, and it is imperative to extend these observables to higher pT. We propose to extract flavor characteristics, specifically strangeness, of jets, the high-pT early probes of heavy ion collisions. Starting with pp, we will measure the strangeness yields in jets to understand the particle fragmentation process, setting the basis for a study in the heavy ion data. In this poster we will introduce the ALICE experiment, we will describe the methodology used for the data analysis and the current status of the data analysis will be presented. [Preview Abstract] |
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EA.00053: PMMA Mechanical Test for the Medium Scale High Voltage Apparatus (MSHV) Adam Clark The nEDM experiment at Oak Ridge National Laboratory (ORNL) aims to search for the electric dipole moment of the neutron (nEDM) at the $10^{-28}$ level. One of the variables proportional to the sensitivity of the measurement is the strength of the electric field. The electrodes that generate the field will be made of polymethyl methacrylate (PMMA) and coated with a conductive material. This unique condition is further complicated by the fact that the system will be cooled to a temperature of 0.4 K. These conditions have not been attempted in the past and provide new challenges. In order to test solutions to these challenges, the MSHV was constructed. This apparatus allows potential coatings to be tested at 0.4 K to ensure that the electrodes for the final design will function as required. Due to stresses from thermal contraction occurring during cool down, components to transition from the PMMA electrodes to the existing support structure had to be selected to minimize the stress on each material. A mechanical test of this structure was performed at Los Alamos National Laboratory (LANL) to ensure that there are no failures of either structure or electrode. The results of this mechanical test, as well as the design and materials selected, will be discussed. [Preview Abstract] |
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EA.00054: Compatibility of photomultiplier tube operation with SQUIDs for a neutron EDM experiment Matthew Libersky An experiment at the Spallation Neutron Source at Oak Ridge National Laboratory with the goal of reducing the experimental limit on the electric dipole moment (EDM) of the neutron will measure the precession frequencies of neutrons when a strong electric field is applied parallel and anti-parallel to a weak magnetic field. A difference in these frequencies would indicate a nonzero neutron EDM. To correct for drifts of the magnetic field in the measurement volume, polarized $^3$He will be used as a co-magnetometer. In one of the two methods built into the apparatus, superconducting quantum interference devices (SQUIDs) will be used to read out the $^3$He magnetization. Photomultiplier tubes will be used concurrently to measure scintillation light from neutron capture by $^3$He. However, the simultaneous noise-sensitive magnetic field measurement by the SQUIDs makes conventional PMT operation problematic due to the alternating current involved in generating the high voltages needed. Tests were carried out at Los Alamos National Laboratory to study the compatibility of simultaneous SQUID and PMT operation, using a custom battery-powered high-voltage power supply developed by Meyer and Smith (NIM A 647.1) to operate the PMT. The results of these tests will be presented. [Preview Abstract] |
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EA.00055: Digital acquisition development for neutron induced fission studies at LANSCE Debra Richman, John O'Donnell, Aaron Couture, Shea Mosby, Steve Wender The Los Alamos Neutron Science Center (LANSCE) is a neutron time of flight facility with a diverse group of experiments dedicated to the study of neutron induced reactions. A powerful proton LINAC is used to produce multiple pulsed neutron beams for which monitoring is required to track the neutron flux and energy distribution for each pulse. Digital DAQ techniques lend themselves well to beam monitoring and many of the experiments. Significant effort is being put into transitioning several traditional analog DAQ systems to state of the art digital systems. The Irradiation of Chips and Electronics (ICE House) and the Total Kinetic Energy of Fission (TKE) experiments are both transitioning to digital for the fall 2013 LANSCE run cycle. These new DAQ systems were built using the CAEN VME digitizer family, and both systems will benefit from reduced module count and zero deadtime. The TKE experiment utilizes FPGA firmware to streamline the acquisition system, as well as provide additional data for further analysis. Details of the implementation process along with preliminary data from both experiments will be presented. [Preview Abstract] |
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EA.00056: Development of the Position Sensitive Ionization Chamber for ANASEN Hannah Gardiner, Jeff Blackmon, Catherine Deibel, Emily Gardiner, Jianping Lai, Amber Lauer, Laura Linhardt, Kevin Macon, Charlie Rasco, Lagy Baby, Yevegn Koshchiy, Grigory Rogachev, Daniel Santiago-Gonzales, Ingo Wiedenhoever, Dan Bardayan, Milan Matos The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array developed for reaction studies using radioactive ion beams to help improve understanding of the nuclear reactions important in stellar explosions. A gas-filled ionization chamber with two position-sensitive anode wire grid planes read out in 32 channels, and 12 alternating anode/cathode planes was developed and tested for use with ANASEN to identify the kinematic trajectory and atomic number of recoiling heavy ions by their relative energy loss. The position sensitive grids are arranged perpendicularly to each other in order to determine the x-y position of each ion with better than 4 mm resolution. This ionization chamber was tested using a stable beam of 12C at FSU. We report on the performance of this test experiment and plans for measurements with radioactive ion beams at FSU. Two other versions of the detector have been constructed and are now in place at the National Superconducting Cyclotron Laboratory and at the ATLAS accelerator facility at Argonne National Laboratory. [Preview Abstract] |
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EA.00057: Magnetic Field and Particle Tracking Simulations for Project 8 Devyn Rysewyk A neutrino is a neutral, weakly interacting particle that was first detected in the 1950s. While first it seemed that the neutrino was massless, there is now solid evidence that says the opposite. Project 8 is a new experiment being developed to measure the neutrino mass. The neutrino mass is measured by using the energy of electrons that are emitted from the beta-decay of tritium, which releases an electron and an antineutrino. A measurement of the beta-decay energy distribution is equivalent to a neutrino mass measurement because it depends on the neutrino mass. Project 8 will detect the electron energy by looking at the cyclotron frequency of the electron while it is moving within a magnetic field. Currently, Project 8 is using a $^{83}$Rb source to see if the method for measuring the electron energy will work. $^{83}$Rb decays to $^{83m}$Kr, and then to $^{83}$Kr. Electrons are emitted in the decay of $^{83m}$Kr to $^{83}$Kr with the energy of about 18 keV and 32 keV. I ran magnetic field simulations to characterize the field that electrons move in. I have also simulated how electrons move through the magnetic field to see if some are trapped and how long they are trapped. I will be presenting field simulations and results from particle tracking simulations. [Preview Abstract] |
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EA.00058: Mississippi State Axion Search Kris Madsen Ever since the Peccei-Quinn Theory was proposed in 1977 as a possible solution to the strong CP problem, the therein postulated Axion, a weakly interacting boson, has been much sought after. The Mississippi State Axion Search is an attempt to improve the limit in the mass-coupling parameter space by using a variation of the Light Shining Through a Wall (LSW) technique. A vacuum sealed and RF shielded cavity is partitioned by a lead wall. EM waves at a frequency between 420 and 430 MHz are amplified by SR-550 and SR-510 amplifiers, broadcast from an antenna on one side of the lead wall and pass through an intense magnetic field. Theory predicts that in the presence of such a magnetic field, axions can be produced from photons via the Primakoff effect. Any axions generated will pass unimpeded to the other half of the cavity, regenerate into photons, and be detected as an excess in the signal picked up by the antenna on the far side. The Data Acquisition is handled by LABView based software running Measurement Computing drivers for two PCI DAQ cards: the DAS-08 handles the analog signals from the receiving antenna and monitors vital statistics in the cavity, while the DIO-24 provides the 1kHz timing TTL pulse and allows remote control of the experiment's systems. [Preview Abstract] |
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EA.00059: Core-Collapse Supernova Nucleosynthesis of Promptly Ejected Material Cody Melton, Carla Frohlich Understanding nucleosynthesis of the heavy elements in core-collapse supernovae is an important step in determining the origin of the heavy elements in the universe. Simulations of core-collapse supernovae produce proton-rich as well as slightly neutron-rich ejecta. The electron fraction, which determines the initial abundances in the explosion, is highly sensitive to the details of the simulations. Here we investigate both proton and neutron-rich ejecta. In the neutron-rich ejecta, we find a new nucleosynthesis pathway consisting of neutron captures and subsequent proton captures between 4 and 3 GK. Proton-rich ejecta produces a weak neutrino-proton process, as seen previously. [Preview Abstract] |
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EA.00060: In-beam gamma spectroscopy of neutron-rich exotic Cu isotopes at NSCL Caleb Bancroft, Kathrin Wimmer The area of the nuclear chart around Ni-68 has attracted much attention recently due to the sub-shell closure at N$=$40. The odd-even and odd-odd Cu isotopes near Ni provide similar characteristics and are a good testing ground for nuclear structure calculations around the shell closure at N$=$40. This experiment was performed at the National Superconducting Cyclotron Laboratory using the S800 spectrometer and the Germanium array, GRETINA. This highly efficient setup allows for unambiguous identification of the reaction products as well as precise measurements of the gamma ray emission angle and energy needed for Doppler reconstruction at intermediate gamma energies. The Cu isotopes were produced at the center of GRETINA by neutron removal reactions from a radioactive Cu-69 beam. Prompt gamma ray transitions were detected in coincidence with the heavy residue nucleus. Using known transitions as well as newly observed gamma transitions and gamma-gamma coincidences, the level schemes of Cu-67, Cu-68, and Cu-69 have been determined. The present status of the analysis and comparison to the shell-model calculations will be presented. [Preview Abstract] |
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EA.00061: Charged Particle Trajectories in Sweeper Magnet for LISA Commissioning Run Alyson Barker, Sierra Garrett, Nathaniel Taylor, Warren F. Rogers The Large multi-Institutional Scintillator Array (LISA) located at NSCL, MSU, is used in conjunction with the Modular Neutron Array (MoNA) and the Sweeper Magnet for experiments investigating the properties of exotic neutron-rich nuclei near the neutron dripline. In the LISA commissioning experiment, designed to study neutron unstable $^{24}$O excited states, decay energy calculations require careful determination of charged fragment and neutron trajectories following breakup. Tracking of charged particles through the Sweeper Chamber is accomplished using two Cathode Readout Drift Chamber (CRDC) detectors separated by 1.8 m. During analysis of individual charged fragment passages through both CRDCs we recognized a majority of events had incomplete charge collection in the center pads. Without correction, standard peak location algorithms incorrectly determined the individual event centroids thereby reducing trajectory resolution. We developed a method and algorithm for correctly determining the centroids to restore trajectory resolution, critical for neutron breakup event reconstruction and decay energy determination. [Preview Abstract] |
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EA.00062: Precise timing calibration for MoNA and LISA detectors Sierra Garrett, Alyson Barker, Nathaniel Taylor, Warren F. Rogers The Modular Neutron Array (MoNA) and the Large multi-Institutional Scintillator Array (LISA), working in conjunction with the Sweeper Magnet and Detector Chamber at the NSCL, MSU, are used to determine the properties of neutron-unbound ground and excited states of neutron-rich nuclei. In order to determine the decay energy, precise energy and trajectory for both the charged fragment and the neutron need to be determined. This requires very precise time calibration for each of the 288 scintillator detectors in the two neutron arrays. Initial timing calibrations for all bars in a vertical layer are achieved using muons passing through all 16 detectors, taking into account the muon transit time from bar to bar. Vertical layers are then ``tied'' to one another using the arrival times of gamma rays originating from the target during production runs. In the LISA commissioning experiment, prompt gamma rays from the contaminant beam $^{29}$Na were used instead of those from the $^{26}$F production beam since they constituted 98\% of the beam intensity (compared with the $^{26}$F production beam). Results for the LISA commissioning experiment will be presented. [Preview Abstract] |
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EA.00063: Isotope Separation and Decay Energy Calculation for LISA Commissioning Experiment Nathaniel Taylor, Alyson Barker, Sierra Garrett, Warren F. Rogers The commissioning experiment for the Large multi-Institutional Scintillator Array (LISA) was designed to investigate properties of neutron-unstable excited states of the $^{24}$O. The array is located at the NSCL, MSU and is used in conjunction with the Modular Neutron Array (MoNA) and the Sweeper Magnet. Oxygen fragments produced by the $^{26}$F secondary beam incident on a Be target are directed through the Sweeper Chamber which includes two tracking CRDC detectors, an ion chamber, and a thin and thick scintillator. Plotting the fragment's trajectory position vs. angle vs. time of flight allows for separation of the individual $^{22, 23, and\, 24}$O isotopes, necessary for the calculation of the decay properties of individual states. Anomalous features in the fragments' emittance distribution, believed to result from little understood issues with the tracking detectors, required that we adopt a slightly different approach than that developed recently by the collaboration. Once the isotopes are successfully separated, decay energies are calculated by applying mass-invariant decay spectroscopy by associating the fragment's precise trajectory (determined by inverse-tracking through the Sweeper Magnet) and energy with those of the emitted neutron. [Preview Abstract] |
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EA.00064: Tracking the Synthesis Paths of P-Process Nuclei Stephanie Boehringer The p-process nuclei are proton-rich nuclei heavier than iron are an astrophysical abnormality because of the enigmatic nature of their synthesis. It is possible to trace the production of the p-process nuclei as a path that starts from thirty-five different p-nuclei to their seed nuclei composed of lighter isotopes. Data from NSCL's nuclear reaction network of a Type II Supernova explosion with a temperature shock front that passes through multiple zones of the O/Ne layer was used to make calculations on the change in abundance of seed nuclei. The flow rates involving p-nuclei were calculated accurately enough to continue calculations on the paths taken by seed nuclei. [Preview Abstract] |
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EA.00065: Inverse-kinematics proton scattering from $^{50}$Ca with a liquid hydrogen target and GRETINA Frank DeVone An inverse-kinematics proton-scattering measurement of $^{50}$Ca was performed by the Ursinus College Nuclear Structure Group at the National Superconducting Cyclotron Laboratory at Michigan State University. The secondary beam was a 90 MeV/u super-cocktail of exotic isotopes centered around $^{50}$Ca. This beam was aimed at a liquid hydrogen target with an effective thickness of 265 mg/cm$^2$ and a temperature of 16 K. GRETINA, the first stage of GRETA (the Gamma ray energy tracking array), was used to measure the gamma rays which were created as a result of inelastic scattering of beam particles from protons in the target. Only half of the GRETINA mounting shell was used to accommodate the liquid hydrogen target. However all seven available detectors were used in this half of the shell. In the experiment, we collected data on 3x10$^7$ $^{50}$Ca particles. GEANT4 simulations of GRETINA allowed us to obtain gamma-ray intensities and inelastic cross sections. Preliminary results will be presented. [Preview Abstract] |
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EA.00066: Applying Renormalization Group Techniques to Nuclear Reactions Zachary Eldredge, Scott Bogner, Filomena Nunes Nuclear reactions are commonly used to explore the physics of unstable nuclei. Therefore, it is important that accurate, computationally favorable methods exist to describe them. Reaction models often make use of effective nucleon-nucleus potentials (optical potentials) which fit low-energy scattering data and include an imaginary component to account for the removal of flux from the elastic channel. When describing reactions in momentum space, the coupling between low- and high-momentum states can pose a technical challenge. We would like potentials which allow us to compute low-momentum interactions without including highly virtual momentum states. A solution to this problem is to apply renormalization group (RG) techniques to produce a new effective potential in which high and low momentum degrees of freedom are decoupled, so that we need only consider momenta below some cutoff. This poster will present results relating to an implementation of RG techniques on optical potentials, including complex potentials and spin-orbit effects. We show that our evolved optical potentials reproduce bound states and scattering phase shifts without the inclusion of any momenta above a selected cutoff, and compare new potentials to old ones to examine the effect of transformation. [Preview Abstract] |
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EA.00067: Inverse-kinematics proton scattering from 46Ar with a liquid hydrogen target and GRETINA Matt Glowacki The Ursinus College nuclear structure group performed an experiment at the National Superconducting Cyclotron Laboratory at Michigan State University in May. We sent a super-cocktail beam of exotic nuclei through a liquid hydrogen target that was cooled to 16 K. We measured these gamma rays in coincidence with outgoing beam nuclei. Then, we compared the gamma-ray spectra with simulations to determine gamma-ray intensities, which are related to the cross sections of populating collective excited states of the nucleus in these collisions. These will help us better understand nuclear shell structure. My work is focused on $^{46}$Ar, a test case for which a similar measurement for cross sections have already been made. Preliminary results will be presented. [Preview Abstract] |
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EA.00068: Photon detection system for laser spectroscopy experiments with cooled/bunched beams at BECOLA facility at NSCL Maximilian Hughes, Kei Minamisono, Paul Mantica, Dominic Rossi, Caleb Ryder, Andrew Klose, David Tarazona, Ryan Strum, Georg Bollen, Ryan Ringle, Brad Barquest, Christopher Geppert The BEam COoler and LAser spectroscopy (BECOLA) facility at NSCL is designed to determine fundamental properties of the atomic nucleus such as the charge radii, the spin and electromagnetic moments. Commissioning tests of BECOLA has been completed using a stable $^{39}$K beam produced from an offline ion source. The $^{39}$K beam was cooled and bunched and propagated collinearly with laser light. The resulting fluorescence was detected in a photomultiplier tube (PMT)sensitive to the wavelength of D1 transition of $^{39}$K The PMT was cooled to minimize background due to dark counts. The resulting fluorescence light was measured as a function of laser frequency and time relative to the $^{39}$K beam bunch. An EPICS-based Control Systems Studio (CSS) was used for data acquisition and the software package Root was used for data analysis. The performance characteristics of the photon detection system as well as the laser spectroscopy of bunched $^{39}$K will be discussed. work was supported in part by the National Science Foundation, Grant PHY-11-02511. [Preview Abstract] |
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EA.00069: Simulating the Scintillating Cosmic Ray Eliminating ENsemble (SuNSCREEN) for reducing cosmic background in experiments relevant for the p-process Emily Klopfer, Artemis Spyrou, Anna Simon, Stephen Quinn, Alexander Dombos, Paul DeYoung, Jaclyn Brett Naturally occurring, proton rich isotopes that cannot be produced in the s- or r- neutron capture processes are called p-nuclei. Their nucleosynthesis proceeds by the p-process; a process that is still not well understood. This process may be studied by measuring (p,$\gamma )$ and ($\alpha $,$\gamma )$ reactions using the Summing NaI(TI) detector (SuN) created at NSCL. The SuN detector uses a summing technique where all the gamma rays emitted from a single compound nucleus are summed into one peak that can then be analyzed. One problem with this method is the background created by cosmic rays at high-energy regions of the gamma spectrum. To counteract this drawback a veto detector, SuNSCREEN (Scintillating Cosmic Ray Eliminating Ensemble), is being developed to reduce this cosmic ray background. The present work was centered on producing a simulation of SuNSCREEN and cosmic rays utilizing GEANT4 software and the comparison of these simulations to experimental data. [Preview Abstract] |
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EA.00070: Evaluating Depth of Interactions within a Planar Germanium Detector for Beta-Decay Spectroscopy Alan Lear A new beta-decay spectroscopy system based on a planar germanium double-sided strip detector (GeDSSD) has recently been implemented at the National Superconducting Cyclotron Laboratory (NSCL). The detector is 1-cm thick with 16 5-mm orthogonal strips on the front and back face. The sensitivity of the system can be improved by determining the location of interaction of charged particles, beta-decay electrons, and low-energy gamma rays with more precision than is allowed based on the strip pitch. Techniques for determining the interaction depth of the gamma rays within the 1-cm thick detector have been studied. Interaction depth was extracted by applying a time difference algorithm to the electron and hole collection times recorded on the back and front detector contacts respectively. A description of the algorithm and its resulting position determination along with future prospects will be presented. [Preview Abstract] |
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EA.00071: Potentials at the Limits of their Existence: Particle-Vibration Coupling in the Nuclear Many-Body Problem Philippe Lewalle, Elena Litvinova, Filomena Nunes, Luke Titus We consider the effects of particle-vibration coupling (PVC) in $^{56}$Ni, both on the potential (Relativistic Mean-Field, or RMF) which models interactions between nucleons, and the energy level distribution. The theoretical approach employed uses single-particle propagators to obtain a self-energy term describing coupling between particles and phonons in the first-order perturbation theory. This self-energy is transformed into coordinate space, where it is combined with the RMF resulting in a non-local optical potential, which is then implemented to calculate nucleon-nucleus scattering. Our work towards obtaining results comparable to scattering data is still in progress; we anticipate improvements in the agreement with data for the total potential, as compared with the RMF alone. Additionally, we continue previous work done with this formalism on energy level distributions by examining the contributions of individual vibrational (phonon) modes to level fragmentation. Analyses of the relative strengths of the fragments in highly-fragmented states through their spectroscopic factors demonstrate that in many cases, only a few phonon modes cause large amounts of fragmentation, but that the others may alter the relative strengths of the fragments caused by those few modes. [Preview Abstract] |
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EA.00072: Commissioning a Hodoscope Detector Andrew Lulis, Abdul Merhi, Nathan Frank, Daniel Bazin, Jenna Smith, Michael Thoennessen Experiments on neutron-rich nuclei are interesting since they test the limits of current nuclear theory. One method to populate neutron-rich nuclei is to utilize the (d,p) reaction in which the beam nucleus picks up a neutron from the target. This heavier nucleus immediately emits a neutron resulting in the same nucleus as the beam but with lower energy. One challenge is to discriminate decay products from unreacted beam particles by their difference in energy. A hodoscope was recently installed at the National Superconducting Cyclotron Laboratory (NSCL) as part of the MoNA-LISA-Sweeper setup to make experiments using a (d,p) reaction possible. The hodoscope is a 5x5 scintillator array consisting of CsI(Na) crystals with a resolution of better than 1{\%}. This presentation will describe the recently commissioned detector and the results of the first data analysis using this device. [Preview Abstract] |
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EA.00073: Breakdown of Isobaric Mass Multiplet Model for the sd-shell Nuclei Aaron Magilligan, B. Alex Brown The Isobaric Multiplet Mass Equation (IMME) relates the masses of Isobaric Analogue States with the same quantum numbers, and is quadratic in form. Many individual cases of isobaric multiplets deviating from the quadratic IMME have been analysed; however a systematic scan of the available data has not been done to the authors' knowledge. We examine the experimental data for Isobaric ground-state Multiplets in the $sd$-shell for inconsistencies of the quadratic IMME. Shell model calculations using two $sd$-shell Hamiltonians, USDA and USDB, are performed for the same region and checked against the quadratic IMME for deviations. Significant corrections to the IMME are found to be needed for the $T = 2$, $A=20$ and the $T=3/2$, $A=35$ ground state multiplets. These corrections are due to nearby states inducing isospin mixing in $^{20}$Ne and $^{35}$Ar; predictions are made for the energies of these levels. They require experimental confirmation of their properties. Our work shows that the breaking of the IMME can be understood in the framework of the $sd$-shell. [Preview Abstract] |
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EA.00074: Segmented Target Design Abdul Rahman Merhi, Nathan Frank, Paul Gueye, Michael Thoennessen A proposed segmented target would improve decay energy measurements of neutron-unbound nuclei. Experiments like this have been performed at the National Superconducting Cyclotron Laboratory (NSCL) located at Michigan State University. Many different nuclei are produced in such experiments, some of which immediately decay into a charged particle and neutron. The charged particles are bent by a large magnet and measured by a suite of charged particle detectors. The neutrons are measured by the Modular Neutron Array (MoNA) and Large Multi-Institutional Scintillation Array (LISA). With the current target setup, a nucleus in a neutron-unbound state is produced with a radioactive beam impinged upon a beryllium target. The resolution of these measurements is very dependent on the target thickness since the nuclear interaction point is unknown. In a segmented target using alternating layers of silicon detectors and Be-targets, the Be-target in which the nuclear reaction takes place would be determined. Thus the experimental resolution would improve. This poster will describe the improvement over the current target along with the status of the design. [Preview Abstract] |
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EA.00075: Analysis of $^{26}$P($\beta^{+}$p$\gamma)^{25}$Al Decay Gamma-ray Spectrum Sarah Schwartz, Christopher Wrede, Michael Bennett The spectrum of gamma rays emitted following the beta-delayed proton emission of $^{26}$P to excited states of $^{25}$Al was analyzed to obtain information about this decay channel. New and existing gamma-ray transitions in $^{26}$P($\beta^{+}$p$\gamma)^{25}$Al were observed and their relative intensities were measured to determine the feeding and branching of excited $^{25}$Al states. Doppler-broadening effects due to the recoil of the daughter nucleus were observed and analyzed in detail for the 1612 keV gamma-ray line. [Preview Abstract] |
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EA.00076: Reduction of power fluctuation of laser light for collinear laser spectroscopy experiments at BECOLA facility at NSCL Ryan Strum, Brad Barquest, Georg Bollen, Kei Miniamisono, David Tarazona, Andrew Klose, Paul Mantica, Dave Morrissey, Max Hughes, Ryan Ringle, Alberto Rodriguez, Dominic Rossi, Caleb Ryder, Stefan Shwarz, Chandana Sumithrarachchi, Cristopher Geppert The BEam COoler and LAser spectroscopy (BECOLA) facility at NSCL/MSU is designed to determine fundamental properties of the atomic nucleus such as the charge radii, nuclear spins and electromagnetic moments. Commissioning tests of BECOLA have been completed using a stable $^{39}$K beam produced from an offline ion source. The $^{39}$K beam was then cooled and bunched using a radiofrequency cooler and buncher, propagated collinearly with laser light and resulting fluorescence was detected. The laser light that was co-propagated with the beam was transported to the experimental area from a remote laser room via a single-mode optical fiber. Random rotation of the polarization of the laser light led to a large fluctuation in laser power, and hence a poor signal-to-noise ratio for the fluorescence measurement. A laser power controller was introduced to mitigate the power fluctuations. The performance characteristics of the power-stabilization system as well as the collinear laser spectroscopy of the bunched $^{39}$K beam will be discussed. [Preview Abstract] |
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EA.00077: Implementation of Gammasphere -- ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) Ian Marsh, Steven Pain, Andrew Ratkiewicz, Sean Burcher Direct reactions involving short-lived nuclei are of great interest to nuclear science. Typically, the light ejectile emitted in the reaction is measured but de-excitation gamma rays from the recoiling nucleus can yield extra information on the states populated and the levels through which they decay. These gamma rays can be measured with significantly better energy resolution than the charged particles. To achieve these measurements, the Oak Ridge Rutgers University Barrel Array of silicon detectors (ORRUBA) is being coupled with Gammasphere, a high-granularity spherical array of Compton-suppressed HPGe detectors. For this coupling the coverage of ORRUBA is extended with custom end-cap detectors, providing a total of 80{\%} azimuthal coverage over 15 -- 165 degrees in polar angle. GODDESS hardware (detector mounts, vacuum chamber, preamplifiers) has been developed, installed, and tested at Argonne National Lab, in preparation for radioactive beam experiments. Data from a $^{\mathrm{249}}$Cf source was collected via digital and analog acquisition systems. Preliminary analysis shows energy and position resolutions of 30 keV and \textless 1mm for alpha-particles were achieved. Optimization of digital techniques for the readout of position-sensitive silicon detectors is under development. [Preview Abstract] |
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EA.00078: ABSTRACT WITHDRAWN |
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EA.00079: Characterization of New VANDLE Bars for Reaction and Decay Experiments Jacob Allen, N.T. Brewer, R. Grzywacz, M. Madurga, S.V. Paulauskas, S.Z. Taylor, J.A. Cizewski, W.A. Peters Neutron detectors are used in studies of neutron rich nuclei which give off neutrons in the process of $\beta $-delayed emission. Understanding the rate of this process helps to create tighter safety margins for nuclear reactors. These decay data as well as data gathered from the reactions associated with neutron emission give information about nuclear properties, which can also be used to model the r-process which is responsible production of elements beyond iron. The Versatile Array of Neutron Detectors at Low Energy [1] was developed in order to understand the answers to some of these problems. VANDLE consists of plastic scintillators and is designed to detect neutrons in energy ranges from $\sim$0.1 to 10 MeV from reaction and decay processes. The use of a Pixie-16 system gives VANDLE a sub-nanosecond Time of Flight resolution [2]. Experiments have already been run with VANDLE with the small (3x3x60 cm) and large (5x5x200cm) bars. New medium size (3x6x120 cm) bars are being prepared for use in future experiments. In addition to VANDLE, the results of the characterization of the medium bars will be presented. \\[4pt] [1] C. Matei et al., PoS(NIC X)138, 1-5 (2008)\\[0pt] [2] M. Madurga et al. AIP Conf. Proc. 1336, 586 (2011). [Preview Abstract] |
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EA.00080: Converting VANDLE Data into ROOT for Merging with other Systems Z.J. Bergstrom, R.L. Kozub, W.A. Peters, R. Ikeyama, S.V. Paulauskas, S. Ahn During the rp-process in novae, nuclei rapidly capture protons to form heavier, proton-rich isotopes. Most of the rp-process reactions are believed to pass through the $^{56}$Ni($p,\gamma$)$^{57}$Cu(1106 keV) reaction which cannot be measured directly. In an experiment performed at the National Superconducting Cyclotron Laboratory (NSCL), the ($d,n$) proton transfer reaction in inverse kinematics at 35 MeV/nucleon was employed, primarily to determine the single particle strength of the 1106-keV (1/2$^-$) level. In addition to their astrophysical significance, the measurements provide data for shell model calculations near doubly magic $^{56}$Ni. Two arrays of plastic scintillators, VANDLE and MoNA/LISA, were coupled in order to detect a wide range of neutron energies via the time-of-flight technique. Charged particle detectors placed in the focal plane of the NSCL Sweeper System were used to identify coincident $^{57}$Cu recoils, reducing random background events. VANDLE data from the experiment are being converted into ROOT trees so they can be merged with the charged particle data for analysis. Preliminary results and details of the ($d,n$) experimental setup will be presented. Research supported by the US DOE and NSF. [Preview Abstract] |
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EA.00081: Calibrations of MoNA-LISA VANDLE $^{56}$Ni(d,n)$^{57}$Cu Experiment R. Ikeyama, J.A. Cizewski, W.A. Peters, Z.J. Bergstrom, S.V. Paulauskas, P.A. DeYoung, J. Hinnefeld, W. Rogers, T. Baumann, M. Jones, J.K. Smith, S.R. Lesher A (d,n) proton transfer experiment, in inverse kinematics, was conducted at the National Superconducting Cyclotron Laboratory using a 35 MeV/nucleon beam of $^{56}$Ni. This experiment used both the Versatile Array of Neutron Detectors at Low Energy (VANDLE) at back angles to detect neutrons with less than 20 MeV and the MoNA-LISA array at forward angles for higher energy neutrons and to cover a large angular range. The experiment attempts to measure the spectroscopic factors of the $^{57}$Cu resonance important in the \(rp\)-process, and determination of the reaction rate. Precise calibrations of all the detector subsystems are crucial for identifying the kinematic signature of the ejected neutrons and the extracting the spectroscopic factors to the different energy levels. Calibrations of the charged particle detectors and the neutron detector arrays are ongoing. Preliminary results pertaining to detector calibrations will be presented as well as details of the experimental setup. [Preview Abstract] |
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EA.00082: Anode Voltage Response Characterization of a Beam Tracking Detector T.L. Johnson, D.M. Robe, R.L. Kozub, S.D. Pain, F. Sarazin, S. Ilyushkin, P.D. O'Malley, B. Manning Fragmenting a primary beam on a thick target and focusing the outgoing fragments using magnetic fields produces secondary radioactive beams. This procedure leads to a large secondary beam spot size on the reaction target. Nevertheless, precise knowledge of the impact point and angle of incidence is sometimes required to calculate scattering angles. For this purpose, multi-wire proportional detectors can be used to provide event-by-event particle tracking. Our prototype design has an anode between two cathodes, each of which is comprised of a plane of wires. The system was mounted in a chamber filled with various gas mixtures and a triple-alpha source was used for testing. Tests were run at various pressures, anode voltages, and gas compositions to characterize the observed signals and tune electronics. Results showing anode voltage effects will be presented. Research supported by the U. S. Department of Energy. [Preview Abstract] |
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EA.00083: Gas Pressure Response Characterization of a Beam Tracking Detector D.M. Robe, T.L. Johnson, R.L. Kozub, S.D. Pain, B. Manning, F. Sarazin, S. Ilyushkin, P.D. O'Malley A detector was designed at ORNL to provide event-by-event position information for radioactive ion beam experiments. The design was five planes of parallel wires in a chamber of CF$_4$ gas, with the second and fourth planes serving as anodes, and the other planes being cathodes. The charge collection on each anode wire could be read out individually, and the centroid of the charge distribution could be used to find the position of an event across the anode. The two anodes would be oriented perpendicular to each other, so each provided one coordinate of an event's position. For initial implementation testing, a single anode plane between two cathodes was constructed, and its responses under certain conditions were tested using a triple alpha source. The detector's response was characterized as a function of the gas pressure inside the test chamber and the presence of a quenching gas. The position, height, and width of peaks in the resulting energy spectra were compared to determine optimal pressure settings for the detector. Also, simulations were performed of energy loss in the chamber, and compared to the results of the tests. Research supported by the U.S. Department of Energy. [Preview Abstract] |
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EA.00084: First Scattering Reaction Using JENSA Gas Jet Target Allison Sachs, Kelly Chipps, Kate Jones, Steven Pain, Michael Smith The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target, currently located at Oak Ridge National Laboratory, is a new target system designed to provide a target of light gases that is localized, dense and pure. Such a target is necessary to answer many open questions in nuclear structure and astrophysics, because it provides hydrogen and helium isotopes without any backing materials, contaminants, window materials, or extended gas cells. In order to characterize the jet, several techniques are used, including energy loss measurements and elastic scattering. The first scattering experiment done with the JENSA gas jet target was a 40 MeV tin-120 beam incident on a jet of nitrogen-15. The results of this experiment will be presented. [Preview Abstract] |
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EA.00085: Evolution of Collectivity with Spin in $^{70}$As R.M. Elder, R.A. Haring-Kaye, S.I. Morrow, S.L. Tabor, V. Tripathi, P.C. Bender, N.H. Medina, P. Allegro, J. D\"{o}ring The high-spin decay of $^{70}$As was studied using the $^{55}$Mn($^{18}$O, $3n$) reaction at 50 MeV and a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors at Florida State University. Based on prompt $\gamma$-$\gamma$ coincidences and $\gamma$-ray relative intensities measured in the experiment, several previously proposed $\gamma$-ray transitions have been confirmed and additional transitions have been placed in the level scheme. In particular, members of a ``missing'' negative-parity, odd-spin band were observed. The yrast positive-parity band shows similarities to those of neighboring odd-odd isotopes, including signature splitting and large alternations in the $B(M1)/B(E2)$ ratios. Kinematic moments of inertia were calculated for each observed high-spin band and roughly indicate a convergence to the expected rigid-body value. Theoretical shape calculations indicate a nearly prolate shape at high spin, as well as a possible oblate shape associated with some low-spin, negative-parity states. [Preview Abstract] |
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EA.00086: $\gamma$ Vibrational Band in $^{70}$Ge S.I. Morrow, R.A. Haring-Kaye, R.M. Elder, S.L. Tabor, V. Tripathi, P.C. Bender, N.H. Medina, P. Allegro, J. D\"{o}ring Excited states in $^{70}$Ge were populated by the $^{55}$Mn($^{18}$O,$p2n$) fusion-evaporation reaction at 50 MeV performed at Florida State University. Prompt $\gamma$-$\gamma$ coincidences were measured with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. Examination of the resulting coincidence relations and relative intensity measurements led to an enhanced $^{70}$Ge level scheme, including an extension of the proposed $\gamma$ vibrational band by four new states. Interpretation of the $\gamma$ band within the context of the staggering parameter $S(I)$ suggests a $\gamma$-soft structure, similar to other light Ge isotopes. Total Routhian Surface calculations for the ground-state band are consistent with a picture of $\gamma$ softness at low spin. [Preview Abstract] |
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EA.00087: The Beam Spin Asymmetry and $T$-odd Effects Daniel Banks, Leonard Gamberg The focus of this research is to model the internal structure of the nucleon based on its momentum and spin-polarization properties. We focus on the beam-spin asymmetry (BSA) in semi-inclusive deep inelastic scattering. When the produced pion's transverse momentum is on the order of quark intrinsic transverse momentum, TMD factorization suggest that the structure function for the BSA is a momentum convolution integral of transverse momentum dependent (TMD) parton distribution and fragmentation functions. Theoretically there are four possible structure functions. We focus on the naive time reversal odd ($T$-odd) contribution. Namely, the $g^\perp$ TMD PDF which relates the transverse spin polarization and transverse momentum of quarks for the case of an unpolarized nucleon and longitudinally polarized electron beam. We model the BSA in the spectator model framework (L. Gamberg et al., Phys. Rev. D77, 094016 (2008)) and calculate $g^\perp$ and extend our earlier numerical work on the BSA for $\pi^+$ to results for $\pi^-$, $\pi^0$, production. We present these new results for the BSA and compare them with the recent results from CLAS, Hall B collaboration at JLAB (M. Aghasyan, H. Avakian et al., Phys. Lett. B704, 397 (2011)). [Preview Abstract] |
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EA.00088: Tracing jet energy loss in relativistic heavy-ion collisions using a multiphase transport model Terrence Edmonds, Fuiqang Wang Energetic partons lose energy in the quark-gluon plasma (QGP) created in relativistic heavy-ion collisions. This jet-quenching phenomenon provides a powerful tool to study the properties of the QGP medium via single particle production rate at high transverse momentum (pt) and two-particle correlation measurements. This REU project studies the effects of parton energy loss on single particle yield and two-particle correlations by tracing energetic partons traversing the heavy-ion medium by using A Multi-Phase Transport (AMPT) model. The AMPT model is modified to output the history information of all parton interactions during the system evolution, in addition to the already available information of the initial state and the final state hadrons from parton coalescence. The initial high-energy partons are followed in each step of their collisions with the medium partons all the way to the final state, before escaping the medium. The particles that they collide with are also tracked. By following high energy particles (jets) and the particles they collide, this project specifically looks at how the direction of the energetic parton is changed via collisions in the medium and how the energy is redistributed in the medium. The implications of the results in terms of interpretations of the experimental jet-quenching and correlation data will be discussed. What additional insights this study can bring to the overall heavy-ion physics research will be outlined. [Preview Abstract] |
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EA.00089: Impurity Detector for the MuSun Experiment Noel Lane, Frederick Gray The MuSun experiment will measure the muon capture rate in deuterium. This process is sensitive to impurities within the deuterium at the part-per-billion level. When a muon is sent into a volume of deuterium it can be captured by an impurity atom, leading to the emission of an x-ray. In order to measure this reaction, a cylindrically symmetric array of ten plastic scintillating panels and five NaI crystals was designed. This apparatus may be placed around the deuterium volume during the experiment. It will observe the number of x-ray events in the NaI detectors that are not accompanied by an electron from the decay of the muon. A simulation was developed using the framework Geant4 to estimate the solid angle acceptance and energy resolution produced by the design. [Preview Abstract] |
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EA.00090: The Neutron Charge Distribution Emily Kraus, Katherine Myers, Arun Tadepalli, April White, Ronald Gilman Based on current knowledge of the neutron electromagnetic form factors and on reasonable extrapolations, we now know that the neutron Breit-frame charge distribution is positive at the origin, whereas the transverse charge distribution is negative at the origin. The long standing bias is that the rest-frame charge distribution should be positive at the origin based on simple pion cloud models; this idea has been used to explain the Breit-frame distribution. A more intuitive result would be if the distributions were similar in shape in the Breit and transverse frames, similar to the case for the proton. Here we explore how the high $Q^2$ behavior of the form factors could make the shapes of the neutron charge distributions more similar in the Breit and transverse frames. [Preview Abstract] |
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EA.00091: Competition Between Single-Particle and Collective Excitations in the Region of 30 $\leq$ Z $\leq$ 38 and 32 $\leq$ N $\leq$ 50 S.L. Rice, Y.Y. Sharon, G.J. Kumbartzki, N. Benczer-Koller The experimental data for the excitation energies and B(E2) reduced transition probabilities for the 2$^+_1$, 4$^+_1$ and 2$^+_2$ states in the long chains of stable and radioactive even-even isotopes of Zn, Ge, Se, Kr and Sr were examined in terms of the competition between single-particle and collective modes of excitation. The magic numbers of 28 and 50 were used for both protons and neutrons. While the level-energy information is not particularly infomative when plotted as a function of the neutron number $N$, the B(E2) values showed obvious trends towards collectivity as $Z$ increases towards the middle of the shell. The data were also analyzed as a function of the number of protons (proton holes) $N_p$ and neutrons (neutron holes) $N_n$ in the valence shells and of the parameter $P$ = $\frac{N_p N_n}{N_p + N_n}$. Increasing values of $P$ correspond overall to larger B(E2)'s but the scatter of the data indicates structures with complex wave functions. [Preview Abstract] |
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EA.00092: Studying Quark-Gluon Plasma with Jets Alexandra DeMaio Quark-gluon plasma (QGP), is a phase of matter consisting of deconfined quarks and gluons, theorized to exist in the early Post-Bang expansion of the universe. At the Large Hadron Collider, QGP is examined via hard probes in heavy-ion collisions. The production of these high-$p_{\mathrm{T}}$ jets is well understood and calculable in the framework of perturbative quantum chromodynamics. We implement the anti-$k_{\mathrm{t}}$ algorithm to reconstruct jets, using the data collected by the Compact Muon Solenoid (CMS) detector. Jet measurements in heavy-ion collisions are compared with those of pp collisions and \begin{scriptsize}PYTHIA + HYDJET\end{scriptsize} calculations at the same energy. In PbPb collisions at $\sqrt{\mathrm{s_{NN}}} = 2.76$ TeV, dijet asymmetry was observed in back-to-back jets, indicating that energy loss occurs as partons traverse the medium. This energy loss appears to increase with collision centrality. In pPb collisions at $\sqrt{\mathrm{s_{NN}}} = 5.02$ TeV, no significant diject momentum imbalance was observed with respect to the pp Monte-Carlo reference, however the dijet pseudorapidity as a function of forward calorimter activity was strongly modified. [Preview Abstract] |
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EA.00093: Strangeness in the Proton Sea David Raschko, Chase Hansen, Greg Netzel A proton consists of three valence quarks: two up quarks and one down quark. Experiments have shown that the proton also has a sea of gluons and quark-antiquark pairs. Zhang, Zhang and Ma [1] used a statistical model to calculate the probabilities of having distinct states of up and down quarks, their antiquarks, and gluons. Their model predicts a $\bar{d}-\bar{u}$ asymmetry in excellent agreement with experiment. We have extended their model to describe the strange quark sea, which is important for an understanding of the intrinsic structure of the proton sea and searches for dark matter candidates. We used RAMBO [2] to include the effects of the strange quark mass, and evolved our distributions to higher $Q^2$ to compare our results to the experimental results of HERMES, ATLAS, and CTEQ. \\[4pt] [1] Yong-Jun Zhang et al., Phys. Lett. B. \textbf{260}, 523 (2001).\\[0pt] [2] R. Kleiss, W.J. Stirling, and S.D. Ellis, Comp. Phys. Comm. \textbf{40} (1986) 359. [Preview Abstract] |
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EA.00094: Momentum distributions of strange and anti-strange quarks in the proton Chase Hansen, David Raschko, Greg Netzel Strangeness in the proton has been confirmed by experiment. We are using the statistical method of Zhang et al. [1], which explained the $\bar{u}-\bar{d}$ asymmetry in the proton. We expand the model to include strange quarks, to explain the existence of strangeness in the proton. We used RAMBO [2] in order to create a Bjorken-x distribution for the partons in the proton. We adjusted RAMBO to include the strange quark mass. In order to suppress the transitions to states that include $s-\bar{s}$ pairs, we calculate energy distributions for the gluons and allow gluons to split into $s-\bar{s}$ pairs only if the gluon is above the energy threshold of twice the mass of a strange quark. We expand our view to include the meson cloud model, attempting a different approach at explaining strangeness in the proton [3]. After $Q^{2}$ evolution, we compare our calculations of strangeness probability and $S^{+}(x)$ to HERMES and ATLAS data, as well as global parton distribution fits.\\[4pt] [1] Yong-Jun Zhang et al., Phys. Lett. B. \textbf{260}, 523 (2001)\\[0pt] [2] R. Kleiss, W.J. Stirling, and S.D. Ellis, Comp. Phys. Comm. \textbf{40} (1986) 359.\\[0pt] [3] F. Cao, and A.I. Signal, Phys. Rev. D. \textbf{60}, 074021 (1999) [Preview Abstract] |
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EA.00095: A meson cloud model of strangeness asymmetry in the proton Greg Netzel, David Raschko, Chase Hansen We use a meson cloud model to describe strangeness in the proton. In this model the proton can fluctuate into meson-baryon pairs, as allowed by the Heisenberg uncertainty principle. The leading contributions to strangeness are from the meson-baryon pairs K$\Lambda$ or K$\Sigma$. In this model, the probability of finding strange quark pairs depends on both the splitting functions, which represent the probability of splitting into a given meson-baryon state, and the phenomenological vertex form factors. Because the s and \={s} quarks reside in different hadrons, their momentum distributions will differ, as suggested by the NuTeV anomaly and recent global parton distribution fits. We compare our results to other theoretical calculations and to experimental data from HERMES and ATLAS, and to global parton distribution fits. [Preview Abstract] |
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EA.00096: The Hadron Blind Ring Imaging Cherenkov Detector Marie Blatnik, Stephanie Zajac, Tom Hemmick Heavy Ion Collisions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven Lab have hinted at the existence of a new form of matter at high gluon density, the Color Glass Condensate. High energy electron scattering off of nuclei, focusing on the low-x components of the nuclear wave function, will definitively measure this state of matter. However, when a nucleus contributes a low x parton, the reaction products are highly focused in the electron-going direction and have large momentum in the lab system. High-momentum particle identification is particularly challenging. A particle is identifiable by its mass, but tracking algorithms only yield a particle's momentum based on its track's curvature. The particle's velocity is needed to identify the particle. A ring-imaging Cerenkov detector is being developed for the forward angle particle identification from the technological advancements of PHENIX's Hadron-Blind Detector (HBD), which uses Gas Electron Multipliers (GEMs) and pixelated pad planes to detect Cerenkov photons. The new HBD will focus the Cerenkov photons into a ring to determine the parent particle's velocity. Results from the pad plane simulations, construction tests, and test beam run will be presented. [Preview Abstract] |
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EA.00097: Removal of long-lived Rn-222 daughters by electropolishing thin layers of stainless steel J. Frascatore, R.W. Schnee, M.A. Bowles, R. Bunker, K. McCabe, J. White, P. Cushman, M. Pepin, V.E. Guiseppe Long-lived daughter particles from the \textsuperscript{222}Rn decay chain may present a limiting background in dark matter detecting experiments. Electropolishing has proven to be an effective method at removing these daughter particles from material surfaces, particularly stainless steel. The removal of \textless 1$\mu$ m of stainless steel reduces the sample daughter contamination by a factor \textgreater \ 100. The total thickness removed due to electropolishing is fairly uniform, as observed by examining samples with a scanning electron microscope. Electropolishing can therefore be used for precision-machined equipment and applications which require the removal of uniform and significantly small thicknesses. Here, the relationship between thickness removed and removal of daughter contamination is studied, including corrections for systematic uncertainties produced by drifts in the digital scale calibration, alpha detector gain drifts, and grow-in of \textsuperscript{210}Po. [Preview Abstract] |
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EA.00098: Ion-Induced Afterpulsing in the Neutron Multiplicity Meter's Photomultiplier Tubes Christopher Nedlik, Richard Schnee, Raymond Bunker, Yu Chen The nature of the dark matter in the Universe remains a mystery in modern physics. A leading candidate, Weakly Interacting Massive Particles (WIMPs), may be detectable via scattering from nuclear targets in terrestrial detectors, located underground to prevent fake signals from cosmic-ray showers. The Neutron Multiplicity Meter (NMM) is a detector capable of measuring the muon-induced neutron flux deep underground, a problematic background for WIMP detection. The NMM is a 4.4-tonne Gd-loaded water-Cherenkov detector atop a 20-kilotonne lead target in the Soudan Mine. It measures high-energy neutrons (\textgreater~50 MeV) by moderating and then detecting (via Gd capture gammas) the secondary neutrons emerging from the lead following a high-energy neutron interaction. The short time scale ($\sim$10 $\mu$s) for neutron capture in Gd-loaded water enables a custom multiplicity trigger to discriminate against the dominant gamma-ray background. Despite excellent rejection of the gamma-ray-induced background, NMM neutron-candidate events are not entirely background-free. One type of background is from ion-induced afterpulsing (AP) in the four 20" Hamamatsu~R7250 photomultiplier tubes (PMTs) used to monitor the NMM's two water tanks. We show that ion-induced AP in the PMTs can mimic the NMM's low-energy neutron response, potentially biasing a candidate event's measured multiplicity. We present detailed studies of the AP in order to allow identification of AP-induced background events. [Preview Abstract] |
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EA.00099: Improved Position Calibration for the FAUST Detector Layla Bakhtiari, Lauren Heilborn, Paul Cammarata, Alan McIntosh, Mike Youngs, Matthew Chapman, Sherry Yennello The Forward Array Using Silicon Technology (FAUST), is a detector array used to measure charged particles resulting from heavy-ion reactions. Studying multifragmentation in these reactions can give insight into the Equation of State of nuclear matter, which is important for understanding concepts in astrophysics such as the formation of the atomic elements, neutron star development, and supernovae behavior. In order to characterize the events more fully, the current silicon detectors will be replaced with position sensitive Dual-Axis Dual-Lateral (DADL) detectors. To maximize the use of these new detectors, a procedure to perform position and energy calibrations with the fully assembled array had to be developed. Testing of the mask will be performed in two stages: a preliminary test with a single ring of the array, followed by a comprehensive test with all rings of FAUST. The new calibration procedure, including the custom designed mask and the in-beam testing results of a single ring, will be presented. [Preview Abstract] |
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EA.00100: Transport efficiency of a cylindrical deflector for TAMUTRAP E.A. Bennett, D. Melconian, P.D. Shidling, M. Mehlman Utilizing the radioactive ion beam (RIB) capabilities of T-REX, the upgrade to the Cyclotron Institute at Texas A{\&}M University, the TAMUTRAP facility will make precision measurements of T$=$2 superallowed beta-delayed proton decays for fundamental symmetry tests. To transport the RIB from production to TAMUTRAP's open-geometry, cylindrical penning trap it must traverse three 90 degree bends in the beam line. With low beam energies of 10 to 15 keV, electrostatic optics can effectively steer the beam through these bends. Given the extensive machining process required to build a spherical electrostatic deflector we examined the feasibility of using a simpler cylindrical design. Simulations and testing of two variants of the cylindrical deflector at 4 keV and 10 keV energies show high relative efficiencies and acceptable beam characteristics. The collected data also provides baseline values to compare with the spherical deflector. Testing results and relative efficiencies will be reported. [Preview Abstract] |
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EA.00101: A Further Test of Internal Conversion Theory with the 88.26-keV $M$4 transition in $^{\mathrm{127m}}$Te Kristyn Brandenburg, Ninel Nica, John Hardy The 106-day isomer in $^{\mathrm{127m}}$Te decays by an 88.26-keV $M$4 transition to the ground state. We have measured the intensity of the gamma rays from this transition relative to the K x-rays, which are produced when it converts. We have also accounted for all impurities that contributed (weakly) to those intensities. Combining our result with the known K-shell fluorescence yield for tellurium of 0.875(4) yields $\alpha_{\mathrm{K}}$ $=$ 489(7) for the K-shell internal conversion coefficient (ICC). Previous ICC measurements on other $M$4 and $E$3 transitions by our group have shown that the effect of the hole created by conversion in the atomic K shell should be included in ICC calculations. Theoretical predictions for $\alpha _{\mathrm{K}}$ that account for the hole in the atomic K shell of $^{127}$Te yield 484(2), while predictions that do not include the hole yield 468(2). Our new result provides further evidence that the hole must be included in ICC calculations. [Preview Abstract] |
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EA.00102: Efficiency Studies for the new Muon Telescope Detector at STAR Hannah Carson The Muon Telescope Detector (MTD) is a new detector subsystem in STAR at the Relativistic Heavy Ion Collider (RHIC). The MTD will contribute to studies of the matter being created in heavy-ion collisions by allowing measurements of the J/Psi meson and the different Upsilon states over a broad transverse momentum range via the reconstruction of their di-muon decays. Simulations to estimate the efficiency of the MTD for detecting muons were performed. The results of these simulations will be presented. [Preview Abstract] |
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EA.00103: Exploring Gluon Polarization in the Proton with STAR Jet Data and the NNPDF Polarized Parton Distributions Andrew Cudd The NNPDF Polarized Parton Distribution Functions (PDF) are a PDF set made using a neural network technique rather than using traditional functional forms. The NNPDF polarized parton distribution includes one hundred different fits, or replicas, that are all considered equally probable. The NNPDF replicas were used to calculate the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive jet production at $\sqrt{s} = 200$ GeV. The calculations were compared to STAR inclusive jet $A_{LL}$ results from 2006 and 2009, and the $\chi^{2}$ was determined for each replica. The $\chi^{2}$ values were used in a reweighting procedure, which the NNPDF group developed, for the inclusion of new data into an existing PDF fit. After the reweighting, the polarization of the gluon is examined. The STAR data provide significant constraining power on the gluon polarization, compared to the unweighted NNPDF set. [Preview Abstract] |
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EA.00104: Commissioning a Rotating Target Wheel Assembly for Heavy Element Studies L.D. Fields, M.E. Bennett, D.A. Mayorov, C.M. Folden The heaviest elements are produced artificially by fusing nuclei of light elements within an accelerator to form heavier nuclei. The most direct method to increase the production rate of nuclei is to increase the beam intensity, necessitating the use of a rotating target to minimize damage to the target by deposited heat. Such a target wheel was constructed for heavy element research at Texas A{\&}M University, Cyclotron Institute, consisting of a wheel with three banana-shaped target cutouts. The target is designed to rotate at 1700 rpm, and a fiber optic cable provides a signal to trigger beam pulsing in order to avoid irradiating the spokes between target segments. Following minor mechanical modifications and construction of a dedicated electrical panel, the rotating target assembly was commissioned for a beam experiment. A 15 MeV/u beam of $^{20}$Ne was delivered from the K500 cyclotron and detected by a ruggedized silicon detector. The beam pulsing response time was characterized as a function of the rational frequency of the target wheel. Preliminary analysis suggests that the K500 is capable of pulsing at rates of up to 250 Hz, which is sufficient for planned future experiments. [Preview Abstract] |
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EA.00105: Helium Gas Regulation System for the Light-Ion Guide Gas Cell Bryan Frazier, Henry Clark, Lixin Chen This is a proof-of-concept project to show that it is possible to construct a cost-effective helium gas regulation system for TAMU Cyclotron Institute's light-ion guide gas cell, using store ordered components. By purchasing the individual necessary parts, we designed and constructed a system that was less expensive than purchasing a pre-constructed system from a manufacturer, and could easily be scaled larger or smaller to accommodate any number of gas bottles. Utilizing LabVIEW software, I was able to write a program that allows the system to be controlled remotely, and an automation program that causes the system to change immediately between bottles, whenever one is almost empty, allowing the system to supply a constant flow of helium gas for several days. Although both the construction and the programming of the system can be seen as rough and unrefined, due to the time-restraints placed on me, the project adequately proves that the concept is valid and entirely possible, as the system is fully functional and able to fulfill its intended purpose. [Preview Abstract] |
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EA.00106: Determining Physical Continuum Background Using the Calculated Cross-Section of the Giant Monopole Resonance Michael Henry The choice of continuum is a limiting factor in the cross-section measurement of giant resonances. The continuum is difficult to calculate due to a number of contributing factors; such as beam impurities, nuclear interactions, and background radiation. Assuming ideal multipole strength distributions and using experimentally determined widths and centroids, a calculation of the expected cross-section is made and then compared with the experimental cross-section measured from alpha scattering on \textsuperscript{90}Zr. This comparison is used to refine our assumptions of the continuum. [Preview Abstract] |
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EA.00107: Exploring Hadron Production from Jets and Quark Gluon Plasma at LHC Katherine Jinkins QCD jets are sprays of hadrons created from a quark or gluon at high energy. Hadrons from jets dominate the hadron spectrum above transverse momenta P$_{T} \approx $ 5-8 GeV/c in ultra-relativistic heavy ion collisions at RHIC and LHC. At smaller momenta, below P$_{T} \approx $ 2 GeV/c, hadron production is well described by hydrodynamics or blast-wave models assuming thermalization, while between 2 and 5 GeV/c hadron production proceeds through quark recombination of an off-equilibrium quark gluon plasma. We improved the jet quenching code PPM to describe the high-momentum hadron data recently published by the ALICE experiment at the LHC. PPM Glauber calculations of the transverse densities of nucleons participating in collisions, and the overall number of participants and collisions (\textit{Npart} and \textit{Ncoll}, respectively) were updated by changing the previous hard sphere approximation of a nucleus to Woods-Saxon profiles. Impact parameters were matched to centrality bins published by the ALICE experiment. Using the sLPM (Landau-Pomeranchuk-Migdal effect) energy loss model for partons in PPM, the energy loss parameter c$_{sLPM} = $ qhat/s was adjusted to achieve a consistent description of high momentum ALICE data. A blast wave model calculation at low momentum was also added to achieve a comprehensive fit to ALICE data. [Preview Abstract] |
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EA.00108: Revisiting the Vector Dominance Model in Radiative Vector-Meson Decays Megan Matthews, Paul Hohler, Ralf Rapp The application of the vector dominance model (VDM) to the Dalitz decay of the omega meson into dimuons and a neutral pion underestimates the experimental spectra, especially when approaching the kinematic limit. Recently, the discrepancy became more apparent as the NA60 experiment at the CERN-SPS re-measured the omega form factor with better precision. In the present work, we augment the baseline VDM by simulating the finite size of the omega-rho-pi vertex through a hadronic form factor, which has been introduced 14 years ago in a different context. The additional momentum dependence predicted by the form factor improves the description of the NA60 data noticeably. In addition, we have improved the intermediate rho propagator by replacing its schematic width with a microscopic model for its vacuum self-energy. This leads to a further, albeit smaller, improvement in the description of the data. As another test of the form factor, we have checked the decay width of the rho meson into a gamma ray and a pion, which turns out to agree with the experimental value. Our results thus support the use of hadronic form factors to simulate finite-size effects in hadronic interactions and improve on an apparent shortcoming of the VDM. [Preview Abstract] |
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EA.00109: TBD Katherine Jinkins |
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EA.00110: Upgrade to the Cryogenic Hydrogen Gas Target Monitoring System Michael Slater, Robert Tribble The cryogenic hydrogen gas target at Texas A\&M is a vital component for creating a secondary radioactive beam that is then used in experiments in the Momentum Achromat Recoil Spectrometer (MARS). A stable beam from the K500 superconducting cyclotron enters the gas cell and some incident particles are transmuted by a nuclear reaction into a radioactive beam, which are separated from the primary beam and used in MARS experiments. The pressure in the target chamber is monitored so that a predictable isotope production rate can be assured. A ``black box'' received the analog pressure data and sent RS232 serial data through an outdated serial connection to an outdated Visual Basic 6 (VB6) program, which plotted the chamber pressure continuously. The black box has been upgraded to an Arduino UNO microcontroller [Atmel Inc.], which can receive the pressure data and output via USB to a computer. It has been programmed to also accept temperature data for future upgrade. A new computer program, with updated capabilities, has been written in Python. The software can send email alerts, create audible alarms through the Arduino, and plot pressure and temperature. The program has been designed to better fit the needs of the users. [Preview Abstract] |
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EA.00111: Knee Structure in Elliptic Flow from Hydrodynamic Simulations for U+U Collisions Andy Goldschmidt, Zhi Qiu, Ulrich Heinz We report on a ``knee''-like structure in the elliptic flow within ultra-central ($<0.5\%$ centrality) U+U collisions at RHIC. A product of the ellipsoidal deformation of Uranium nuclei, the knee arises from a preferential selection of tip-on-tip collisions in very high multiplicity events. It is seen in the centrality dependence of the initial ellipticity of the collision profile, and found well preserved in the elliptic flow after event-by-event hydrodynamic evolution. In the knee region the conversion efficiency $v_2/\varepsilon_2$ between the initial ellipticity $\varepsilon_2$ and the final elliptic flow $v_2$ is found to be almost independent of multiplicity. We argue that a non-monotonic structure of $v_2/\varepsilon_2$ as a function of collision centrality seen by the STAR Collaboration must be a model artifact. We discuss the sensitivity of our results to event-by-event fluctuations of the multiplicity per wounded nucleon. We find that the knee structure survives standard $\Gamma$-distributed multiplicity fluctuations, and that extinguishing effects found in a fluctuation model recently studied by Rybczynski et al. [Phys. Rev. C 87 (2013) 044908] are caused by the extreme hot spots included in that model. [Preview Abstract] |
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EA.00112: Measuring Shallow Impurities in High-Purity Germanium Crystals with Photo-Thermal Ionization Spectroscopy (PTIS) Fanyi Jian, Jayesh Govani, Gang Yang, Guojian Wang, Hao Mei, Dongming Mei High-purity germanium (HPGe) single-crystals grown for the fabrication of radiation detectors required extremely low level (10$^{9}$-10$^{10}$ atoms/cm$^{3})$ of shallow impurities, which are from different sources. As a result it is exceptionally imperative to identify them and understand the associated sources. Among available different semiconductor characterizations techniques, only Photo-Thermal Ionization Spectroscopy (PTIS) is sensitive to the identification of low-level shallow impurities. PTIS characterization helps to identify these impurities and their possible sources in the crystal growth so that the methods to reduce them can be developed, which allows us to grow crystals with the required qualities reliably. In the present study, we have carried out PTIS analysis on HPGe single crystals grown at USD. Our results demonstrated that Al, B and Ga are the dominant impurities in p-type samples and P is the dominant impurities in the n-type samples. Sponsored by Department of Energy - DE-FG02-10ER46709 and the State of South Dakota [Preview Abstract] |
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EA.00113: High-Purity Germanium Crystals Study for Underground Experiments Lu Wang, Gang Yang, Jayesh Gavoni, Guojian Wang, Hao Mei, Dongming Mei The main characterization is the measurement of electrical properties such as carrier concentration, carrier mobility, resistivity of germanium crystal, as well as to identify whether the crystal is n-type or p-type. Van der pauw Hall effect measurement is conducted at room temperature and 77K separately for measuring electrical properties for shallow level impurities. The results show that the ionized impurity level of crystals grown in our lab has reached about 10$^{10}$ /cm$^{3}$. The accumulated data are applied with theoretical analysis. The study of mobility reveals the different scattering mechanisms involved with impurities and lattice vibrations of the crystal. Theoretical calculations have been performed with reasonable parameter assumption and then compared with experimental data. It is found that neutral impurity concentration constrains mobility at 77K while ionized impurity is within the acceptable range (below 10$^{12}$/cm$^{3})$ in germanium crystals. Mobility can increase significantly when neutral impurity concentration is below 10$^{14}$/cm$^{3}$. Therefore, a large reduction of neutral impurity is a desirable approach for obtaining larger mobility, which would improve timing response of germanium detectors. [Preview Abstract] |
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EA.00114: New formulation of target mass corrections in deep-inelastic lepton-nucleon scattering Matthew D. Brown, Wally Melnitchouk, Fernanda Steffens The description of deep-inelastic lepton-nucleon scattering at finite values of $Q^2$ requires subleading corrections such as those arising from target mass corrections (TMCs) to be accounted for, particularly at large values of the parton momentum fraction $x$. The standard method of incorporating TMCs via Nachtmann moments of structure functions, constructed from local operators within the operator product expansion, is known to have practical difficulties reproducing the corresponding Cornwall-Norton moments of the structure functions without TMCs. We consider several potential resolutions of this paradox, and discuss consequences for the interpretation of parton distributions at finite values of $Q^2$. [Preview Abstract] |
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EA.00115: Development of the Low Granularity Pair Spectrometer counters in Hall D at JLab Nathan Dzbenski, Tamara McNeel, Kyle Bowman The pair spectrometer in the photon beam line of Hall D at JLab is designed to monitor the stability of photon flux and the relative tagging efficiency of the photon tagger via a well known electron-positron pair production measurement. The pair spectrometer consists of a thin foil converter, a dipole magnet, and two identical left and right arm detector packages. Each detector package covers the electron or position energy from 3 GeV to 6.25 GeV. It consists of a front detector array for fine position resolution and rear scintillating hodoscopes to provide fast timing to form the pair production trigger. This presentation will focus on the construction and testing of the Low-Granularity Pair Spectrometer counters. [Preview Abstract] |
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EA.00116: Beam Diagnostics of the Compton Scattering Chamber in Jefferson Lab's Hall C Adam Faulkner Upcoming experimental runs in Hall C will utilize Compton scattering, involving the construction and installation of a rectangular beam enclosure. Conventional cylindrical stripline-style Beam Position Monitors (BPMs) are not appropriate due to their form factor; therefore to facilitate measurement of position, button-style BPMs are being considered due to the ease of placement within the new beam enclosure. Button BPM experience is limited at JLAB, so preliminary measurements are needed to characterize the field response, and guide the development of appropriate algorithms for the Analog to Digital receiver systems. -field mapping is performed using a Goubau Line (G-Line), which employs a surface wave to mimic the electron beam, helping to avoid problems associated with vacuum systems. Potential algorithms include simplistic 1/r modeling (-field mapping), look-up-tables, as well as a potential third order power series fit. In addition, the use of neural networks specifically the multi-layer Perceptron will be examined. The models, sensor field maps, and utility of the neural network will be presented. Next steps include: modification of the control algorithm, as well as to run an in-situ test of the four Button electrodes inside of a mock beam enclosure. The analysis of the field response using Matlab suggests the button BPMs are accurate to within 10 mm, and may be successful for beam diagnostics in Hall C. More testing is necessary to ascertain the limitations of the new electrodes. [Preview Abstract] |
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EA.00117: Non-linear Multidimensional Optimization for use in Wire Scanner Fitting Alyssa Henderson, Balsa Terzic, Alicia Hofler To ensure experiment efficiency and quality from the Continuous Electron Beam Accelerator at Jefferson Lab, beam energy, size, and position must be measured. Wire scanners are devices inserted into the beamline to produce measurements which are used to obtain beam properties. Extracting physical information from the wire scanner measurements begins by fitting Gaussian curves to the data. This study focuses on optimizing and automating this curve-fitting procedure. We use a hybrid approach combining the efficiency of Newton Conjugate Gradient (NCG) method with the global convergence of three nature-inspired (NI) optimization approaches: genetic algorithm, differential evolution, and particle-swarm. In this Python-implemented approach, augmenting the locally-convergent NCG with one of the globally-convergent methods ensures the quality, robustness, and automation of curve-fitting. After comparing the methods, we establish that given an initial data-derived guess, each finds a solution with the same chi-square- a measurement of the agreement of the fit to the data. NCG is the fastest method, so it is the first to attempt data-fitting. The curve-fitting procedure escalates to one of the globally-convergent NI methods only if NCG fails, thereby ensuring a successful fit. This method allows for the most optimal signal fit and can be easily applied to similar problems. [Preview Abstract] |
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EA.00118: Construction and Testing of Data Acquisition Components for the Hall A Compton Polarimeter Joshua Hill Nuclear physics experiments require accurate knowledge of the spin polarization of the electron beam delivered to the experimental halls. Hall A is upgrading its Compton polarimeter in support of the lab's 12 GeV beam energy upgrade. This project centered around the data acquisition (DAQ) system for the scattered-photon detection component of the polarimeter. The goal was to test whether the DAQ software and hardware are capable of capturing, recording, and processing electron helicity-dependent scattering rate asymmetry data at high rates, while maintaining appropriate accuracy. We created the necessary circuits, and are able to reliably extract asymmetries of between 0.5{\%} and 11.5{\%} to 0.2{\%}. We did this in a deadtime-free regime at rates between 100 KHz and 350 KHz. We currently are unable to measure the system deadtime after it becomes manifest at about 350 KHz. These tests support the use of a scaled version of this configuration. [Preview Abstract] |
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EA.00119: Optimization of Spin-Polarization of Helium-3 Target Cell by Thermal Convection Processes Stacy Karthas Polarized Helium-3 (3He) is an effective polarized neutron target that has been used in particle accelerators like the Thomas Jefferson National Accelerator Facility (TJNAF) for the past three decades to study properties of the neutron. Due to the spin structure of its nucleons, the nucleus of 3He can be approximated as a single polarized neutron. The previous generations of 3He targets have reached their limit in polarization and are not ideal for use as targets with the 12 GeV update at TJNAF due to large polarization gradients. The new target cell uses thermal convection to transfer polarized gas to the target chamber quickly. The focus of this project was to study the effects of the new convection system, at various gas velocities, on Adiabatic Fast Passage (AFP) polarization loss that results from measuring the polarization of 3He with Nuclear Magnetic Resonance (NMR). Gas velocities were varied by using a Kapton flexible heater to induce thermal convection. This target cell loses less than one percent of its polarization by measurement when convection is induced at a gas velocity under 6 cm/min thereby verifying the possible use of convection induction for the future experiments. [Preview Abstract] |
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EA.00120: Study of the New Pulse NMR System for the Jefferson Lab Helium-3 Polarized Target Joseph Newton At Jefferson Lab, a polarized Helium-3 target is used to study the neutron. The Helium-3 target is undergoing an upgrade to improve its polarization. Measuring it involved a new technique known as pulse Nuclear Magnetic Resonance (NMR). The focus of this project was to find noise in the Pulse NMR signal and to compute the calibration constant to make the polarization easier to deduce. Pulse NMR calibration tests were performed by doing AFP NMR measurements followed by Pulse NMR measurements while varying certain conditions. These included the convection heater, the operation of the oven, and the operation of the laser. Data analysis was done by fitting the pulse NMR signal from the oscilloscope and utilizing the Fourier Transform. Noise was analyzed in the fitting and the Fourier Transform. The calibration constants were affected by the convection heater. The values deviated between the pumping and target chambers of the cell when there was no convection but the values were closer when convection was induced. As far as the noise, it was found to be significant. These results will enable the calculation of the polarization with pulse NMR. In addition, the signal analysis provided insight into the influence of background noise on the pulse NMR measurement. [Preview Abstract] |
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EA.00121: Experimental Setup for Magnetic-Field Tests of Small-Size Light Sensors at Jefferson Lab Cameron Nickle In preparation for the Electron Ion Collider, small-size sensors, such as Silicon photo-multipliers (SiPM) and Multi-Channel Plate (MCP) photo-multipliers are being considered for use in a Detection of Internally Reflected Cherenkov Light (DIRC) detector. Since DIRC will be operated in the strong field of a magnetic spectrometer, the gain of the sensors must be evaluated in high magnetic fields. A dedicated test facility, which makes use of a solenoid magnet with magnetic fields of up to 4.7 T, is being developed at Jefferson Labs. This paper describes the configuration and operation of an entirely non-magnetic dark box that will house the sensors during the tests and allows the sensors to be rotated about two axes relative to the field. This paper also describes the development of a ROOT-based analysis method to extract the gain of SiPMs from raw Analog-to-Digital-Converter (ADC) spectra as a function of the intensity of the magnetic field and the sensor's relative to angle to the field. The dark box and analysis method was tested with Hamamatsu mulitpixel SiPMs and our results are consistent with previous measurements of the same sensors. The methodology developed in this work will be routinely used for the upcoming high-B field tests. [Preview Abstract] |
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EA.00122: Light Yield Measurements of Heavy Photon Search (HPS) Muon Scintillator Hodoscopes MariAnne Skolnik, Stepan Stepanyan The HPS is an experiment that will search for new heavy vector boson(s) in the mass range of 20 MeV/c$^{2}$ to 1000 MeV/c$^{2}$. One of the detectors used for this experiment is a muon hodoscope. We are interested in finding the light yield for the scintillator -- wavelength-shifting fiber coupling that will be used in this muon hodoscope. The muon hodoscope will have background signals distorting the data. In order to reduce the background, a threshold cut will be made on the signal coming from the photo-detector. Precision of this cut depends on the average number of photoelectrons, N$_{pe}$. Previous tests have shown that N$_{pe}$ with Wavelength Shifting (WLS) fibers placed through the holes that go lengthwise down the scintillator is $\sim$12/MeV. In this new muon hodoscope the scintillators will have WLS fibers glued inside the holes. The optical epoxy allows more light, changing N$_{pe}$. To find N$_{pe}$, two scintillators with fibers will be used, one of which will have glued WLS fibers. Light will be readout out using photo multiplier tubes (PMTs). The system of two scintillator-fiber-PMTs and one trigger PMT with a scintillator are placed in a dark box. First, position of a single photoelectron peaks is found using an LED light, then using the signal from cosmic muons from trigger PMT light yield is measured. Data are analyzed using ROOT macros. Result of this measurement suggests that light yield form glued fibers is higher than from WLS fibers without glue by a factor of $\sim$1.7, which is sufficient for operation of the HPS muon hodoscope. [Preview Abstract] |
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EA.00123: Evaluating the Field Emission Characteristics of Aluminum for DC High Voltage Photo-Electron Guns Rhys Taus, Matthew Poelker, Eric Forman, Abdullah Mamun High current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces electron beam. Most of the laser light ($\sim$ 65\%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. This work evaluates the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity: aluminum and copper. These electrodes could serve as effective heat sinks, to passively cool the photocathode that resides within such a structure. However, literature suggests ``soft'' materials like aluminum and copper are ill suited for photogun applications, due to excessive field emission when biased at high voltage. This work provides an evaluation of aluminum and copper electrodes inside a high voltage field emission test stand, before and after coating with titanium nitride (TiN), a coating that enhances surface hardness. [Preview Abstract] |
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EA.00124: Modeling Sugar Allocations in Plants using Radioisotope Tracer Data Mingru Bai The allocations of carbon and nitrogen are major factors in determining growth priorities in plants. The mechanisms that regulate resource allocation in plants are poorly understood. We use radiotracer techniques to identify and quantify dynamical feedback responses of plants to changes in environmental conditions. A major goal of this research is to investigate shifts in sugar allocations as part of the plant's response to changes in environmental conditions. These observations are used to develop mechanistic models that simulate the feedback for adjustments to resource allocations based on the environment-plant interface. By writing a software module in C$++$ based on the models, we are able to conduct a computer simulation of plant's intake of carbon dioxide and sugar allocation inside plant body. By comparing and matching the simulation results and experimental data through adjusting model parameters, we are able to gain knowledge of the mechanisms that regulate resource allocation in plants. [Preview Abstract] |
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EA.00125: Next Generation Beta Decay Studies: Refinements in Detector System Calibration and Response Function Measurements Kenneth Jutz High precision $\beta $-decay studies provide constraints on extensions to the standard model of particle physics. In order to continue to provide competitive limits with LHC measurements for new tensor and scalar interactions, the uncertainties in neutron and nuclear $\beta $-decay studies must be pushed to the 0.1{\%} level and below. In order to control the systematic errors in particle detection at these levels, new detector systems (highly-segmented, large area, thick Si detectors) are being implemented. In order to realize gains in detector response, new capabilities must be developed to calibrate the detectors and characterize their response function. As an alternative to conventional sources mounted on thin foils, an electron beam provides a regular grid of calibration and detector response measurements which are essentially unperturbed by scattering effects. We have developed a 1 MeV electron accelerator that will deliver electrons in a tunable range covering the energy spectrum of neutron $\beta $-decay. We present our efforts to implement this accelerator as well as our development of thin backing foils and detector systems in this poster. [Preview Abstract] |
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EA.00126: Measurement of the Isovector Giant Quadrupole Resonance in $^{124}$Sn Using Polarized Photon Scattering James Park, Gerald Feldman, Mark Sikora, Mohammad Ahmed, Jonathan Mueller, Luke Myers, Henry Weller, Heiko Scheit The High Intensity Gamma-Ray Source (HIGS) at the Triangle Universities Nuclear Laboratory provides energetic and polarized gamma-ray beams at fluxes of 10$^{7}$ gammas/s on target. At HIGS, we have used a linearly polarized photon beam to measure the polarization asymmetry of the Compton scattering cross sections perpendicular and parallel to the plane of polarization of the incident photon beam to investigate the isovector giant quadrupole resonance (IVGQR) in a $^{124}$Sn target over a range of fifteen photon energies between 20.0 and 34.0 MeV. Eight NaI detectors were used to measure the photon scattering cross sections at both forward (55$^{\circ})$ and backward (125$^{\circ})$ angles, which made it possible to unambiguously determine the resonance energy position of the broad IVGQR strength distribution. The fact that the E1/E2 interference term changes sign between the forward and backward angles provides a clear signature of the presence of E2 strength. By dividing the sum of the photon counts in the horizontal plane by the sum of the photon counts in the vertical plane, we obtained polarization ratios for each photon energy, allowing us to determine the polarization asymmetry for the target, $^{124}$Sn, as a function of incident photon energy. The data were fitted with a phenomenological model for the IVGQR by varying the resonance energy, width, and strength. [Preview Abstract] |
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EA.00127: Cherenkov Source for PMT Calibrations Tanner Kaptanoglu My research is focused on building a deployable source for PMT calibrations in the SNO+ detector. I work for the SNO+ group at UC Berkeley headed by Gabriel Orebi Gann. SNO+ is an addition to the SNO project, and its main goal is to search for neutrinoless double beta decay. The detector will be monitored by over 9500 photomultiplier tubes (PMTs). In order to characterize the PMTs, several calibration sources are being constructed. One of which, the Cherenkov Source, will provide a well-understood source of non-isotropic light for calibrating the detector response. My goal is to design and construct multiple aspects of the Cherenkov Source. However, there are multiple questions that arose with its design. How do we keep the scintillation light inside the Cherenkov source so it does not contaminate calibration? How do we properly build the Cherenkov source: a hollow acrylic sphere with a neck? Can we maintain a clean source throughout these processes? These are some of the problems I have been working on, and will continue to work on, until the deployment of the source. Additionally, I have worked to accurately simulate the physics inside the source, mainly the energy deposition of alphas. [Preview Abstract] |
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EA.00128: Measuring characteristics of Hamamatsu Multi Pixel Photon Counter for Electromagnetic Calorimeters Adam Lamson The poster presents the results of the characterization of the Hamamatsu Multi-pixel photon counter (MPPC), a type of Silicon Photomultiplier (SiPM), which will be used for the readout of a prototype barrel electromagnetic calorimeter (EMC). The next generation of high-energy particle experiments, such as the proposed Electron Ion Collider (EIC) at Brookhaven National Labs, require high resolution EMCs with $4\pi$ coverage. SiPMs are attractive because of their ability to operate in the presence of strong magnetic fields and high neutron fluxes while retaining a compact size. We analyzed a large batch (280) of these detectors for their gain, relative photon detection efficiency and optical cross talk as a function of bias voltage and temperature. Prototype EIC detectors designed with these SiPM calorimeters will be tested at FermiLab in February 2014. [Preview Abstract] |
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EA.00129: Optimization of light collection scheme for forward hadronic calorimeter for STAR experiment at RHIC Maria Sergeeva We present the results of the optimization of a light collection scheme for a prototype of a sampling compensated hadronic calorimeter for upgrade of the STAR detector at RHIC (BNL). The absolute light yield and uniformity of light collection were measured with the full scale calorimeter tower for different types of reflecting materials, realistic mechanical tolerances for tower assembly and type of coupling between WLS bars and photo detectors. Measurements were performed with conventional PMTs and silicone photo multipliers. The results of these measurements were used to evaluate the influence of the optical collection scheme on the response of the calorimeter using GEANT4 MC. A large prototype of this calorimeter is presently under construction with the beam test scheduled early next year at FNAL. [Preview Abstract] |
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EA.00130: A repair station for HpGe detectors Robert Shearman, Christopher Lister, A.J. Mitchell, Patrick Copp, Steven Jepeal, Partha Chowdhury Hyper-pure Germanium detectors (HpGe) offer the highest energy resolution for gamma-ray nuclear spectroscopy (about 1.5 keV @ 1 MeV), and are used in all the world's leading detector arrays such as GammaSphere, AGATA and GRETINA. The detector crystals are operated in cryostats at 100 K to reduce thermal noise. To maintain low leakage current and low operating temperatures, cryostat hygiene is very important. Detectors must be regularly maintained by using a high-vacuum, oil-free annealing station. At elevated temperatures above 373 K the process of pumping and baking can also anneal away neutron damage to the detector crystals. This poster will show the design and building of a new HpGe repair station at U. Mass Lowell, and make comparisons of results obtained from this new station to the Gammasphere annealing factory at Argonne. [Preview Abstract] |
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EA.00131: Proton-Induced X-Ray Emission Analysis of Crematorium Emissions Salina Ali, Benjamin Nadareski, Alexandrea Safiq, Jeremy Smith, Josh Yoskowitz, Scott LaBrake, Michael Vineyard There has been considerable concern in recent years about possible mercury emissions from crematoria. We have performed a particle-induced X-ray emission (PIXE) analysis of atmospheric aerosol samples collected on the roof of the crematorium at Vale Cemetery in Schenectady, NY, to address this concern. The samples were collected with a nine-stage cascade impactor that separates the particulate matter according to particle size. The aerosol samples were bombarded with 2.2-MeV protons from the Union College 1.1-MV Pelletron Accelerator. The emitted X-rays were detected with a silicon drift detector and the X-ray energy spectra were analyzed using GUPIX software to determine the elemental concentrations. We measured significant concentrations of sulfur, phosphorus, potassium, calcium, and iron, but essentially no mercury. The lower limit of detection for mercury in this experiment was approximately 0.2 ng/m3. We will describe the experimental procedure, discuss the PIXE analysis, and present preliminary results. [Preview Abstract] |
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EA.00132: Comparing Neutron Capture and Beta Decay r-Process Sensitivity Studies Christopher Allen, Sean Collison, Ana Mikler, Rebecca Surman We used sensitivity studies for r-process nucleosynthesis to determine which pieces of nuclear data are most important for the r-process, as well as develop an understanding of how the r-process proceeds. This summer we compared a neutron capture rate sensitivity study with a beta decay rate sensitivity study. The neutron capture rate sensitivity study procedure began with successful r-process conditions. We then ran a baseline simulation then repeated the simulation thousands of times with the neutron capture rate of each nucleus individually modified by a factor of 100. The results were run compared with a beta decay sensitivity run with the same astrophysical conditions. There was a slight correlation between the sensitivity measures of each type of nuclear data. The differences between the neutron capture and beta decay sensitivity studies can be explained by understating the mechanism that each individual neutron capture rates and individual beta decay rates influence the r-process. [Preview Abstract] |
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EA.00133: Micro-Raman Spectroscopy to Complement Proton-Induced X-Ray Emission in the Analysis of Atmospheric Aerosols Alexandrea Safiq, Salina Ali, Benjamin Nadarski, Jeremy Smith, Josh Yoskowitz, Scott LaBrake, Michael Vineyard There is an active research program in the Union College Ion-Beam Analysis Laboratory on proton-induced X-ray emission (PIXE) analysis of atmospheric aerosols. PIXE is a powerful tool for the study of airborne pollution because it provides information on a broad range of elements simultaneously, has low detection limits, is nondestructive, does not require large samples, and the analysis can be performed in a short amount of time. However, PIXE provides only elemental information. We are investigating the use of Micro-Raman spectroscopy (MRS) to complement PIXE analysis of aerosol samples by providing chemical information. In MRS, laser light is inelastically scattered from a sample and the vibrational spectrum of the scattered light is used to identify molecules and their functional groups. We are focusing on aerosol samples collected in the Adirondack Mountains that have considerable concentrations of sulfur that may contribute to acid rain. The MRS spectra collected on aerosol samples are being compared with a library of standards to try to determine the molecular structures in which the sulfur is bound. We will describe the analysis and present preliminary results. [Preview Abstract] |
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EA.00134: Analysis of Atmospheric Aerosols Collected in an Urban Area in Upstate NY Using Proton Induced X-ray Emission (PIXE) Spectroscopy Jeremy Smith, Salina Ali, Benjamin Nadareski, Alexandrea Safiq, Joshua Yoskowitz, Scott Labrake, Michael Vineyard We examined atmospheric aerosol samples collected in Schenectady NY for evidence of pollution. We collected aerosol samples using a nine stage cascade impactor which distributes the particulate matter by aerodynamic size onto 7.5 $\mu$m Kapton foils. We then used a 1MV electrostatic Pelletron accelerator to produce a 2.2MeV proton beam to hit the impacted foils. X-ray intensity versus energy spectra were collected using an Amptek x-ray detector where the x-rays are produced from the proton beam interacting with the sample. This is called PIXE. The elemental composition and concentrations of the elements present in the aerosol samples were determined using a software package called GUPIX. We have found elements ranging from Al to Pb and in particular have found significant amounts of Pb and Br on some of our impacted foils, with a Br/Pb ratio of 0.6 $\pm$ 0.2 which agrees with previous studies. This result suggests the presence of leaded aviation fuel perhaps due to the proximity of the collection site to a small airport with a significant amount of general aviation traffic. [Preview Abstract] |
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EA.00135: PIXE Analysis of Atmospheric Aerosol Samples Collected in the Adirondack Mountains Josh Yoskowitz, Salina Ali, Benjamin Nadareski, Alexandrea Safiq, Jeremy Smith, Scott Labrake, Michael Vineyard We have performed an elemental analysis of atmospheric aerosol samples collected at Piseco Lake in Upstate New York using proton induced x-ray emission spectroscopy (PIXE). This work is part of a systematic study of airborne pollution in the Adirondack Mountains. Of particular interest is the sulfur content that can contribute to acid rain, a well-documented problem in the Adirondacks. We used a nine-stage cascade impactor to collect the samples and distribute the particulate matter onto Kapton foils by particle size. The PIXE experiments were performed with 2.2-MeV proton beams from the 1.1-MV pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. X-Ray energy spectra were measured with a silicon drift detector and analyzed with GUPIX software to determine the elemental concentrations of the aerosols. A broad range of elements from silicon to zinc were detected with significant sulfur concentrations measured for particulate matter between 0.25 and 0.5 $\mu$m in size. The PIXE analysis will be described and preliminary results will be presented. [Preview Abstract] |
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EA.00136: Determining the Hierarchy of Neutrino Masses Using Discrete Fourier Analysis Daine Danielson Neutrinos are among the least understood elementary particles, with theorized properties capable of addressing major open problems in modern physics such as the disparity between matter and antimatter present in the observed universe. Determining the hierarchy of the three observed neutrino mass states would mark a major milestone in unlocking these particles' secrets. The sign of $\Delta{m^{2}}_{32}$--the ordering of the second and third squared neutrino masses--is unknown; a positive value defines the ``normal,'' and negative the ``inverted,'' mass hierarchy. Analyzing simulated neutrino detector outputs, we implement a discrete Fourier transform of detection rate as a function of neutrino flight distance over neutrino energy. Employing the discrete Fourier transform, we compare the transformed frequency domain spectrum to the predicted normal and inverted hierarchy spectra to determine the hierarchy present in the detected data. Using this technique, an experimental determination of the sign of $\Delta{m^{2}}_{32}$ may be possible, which would bring resolution to the neutrino mass hierarchy problem. [Preview Abstract] |
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EA.00137: Measuring Muon Spin Precession in an Experiment for an Advanced Undergraduate Laboratory Abishek Reddy Wdaru The advanced undergraduate laboratory at the Physics Department at the University of Illinois uses stopped cosmic ray muons to observe their spin precession. The experiment uses a stack of alternating layers of scintillator and absorber plates located in a transverse magnetic field. Stopped negative muons are captured quickly through inverse beta decay. However, the spins of the remaining positively charged stopped muons precess around the transverse magnetic field. The spin precession frequency is measured by observing the difference in yields of decay positrons counted in the scintillators above and below the absorber plate holding a given stopped muon as function of time. Six groups of students assemble the experiment over the course of each semester and use the apparatus to carry out measurements of increasing degree of complexity: muon lifetime, muon capture, various calibration tasks and finally the spin precession measurement. The progress of the experiment is documented by the students through daily entries in the electronic logbook, bi-weekly reports and a monthly presentation in the laboratory seminar. In this contribution we describe the experimental setup, its use in an advanced undergraduate lab and a recent effort to refurbish and further improve the experiment. [Preview Abstract] |
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EA.00138: Electron Microscope and Spectral Analysis of Sense Wires used in COMPASS Drift Chambers Vivek Britto COMPASS is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton. One specific area of research is the measurement of single transverse spin asymmetries in pion beam induced Drell-Yan production of muon pairs from polarized proton targets that may be indicative of contributions from quark orbital angular momentum to the spin of the proton. The University of Illinois (UIUC) is designing and building two new drift chambers to replace older, aging detectors in the COMPASS spectrometer. As a preliminary study, prototype drift chambers were constructed at UIUC. From a similar chamber constructed by CEA Saclay and operated in COMPASS it was previously found that the gold-plated tungsten sense wires had accumulated significant carbon deposits on their surfaces. If this were to occur for a sustained period of time, it would force an increase in the operating voltage of the chamber and might severely limit its efficiency. As a result, it was decided to remove sense wires from the UIUC prototype after an extended period of operation, in order to perform detailed microscopic and spectral analysis in a search for possible deposits on the sense wires. The presentation will cover the methods of testing employed and their results. [Preview Abstract] |
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EA.00139: Tension measurements for COMPASS-II prototype drift chamber Christopher Campbell COMPASS-II is an approved fixed target experiment at CERN's Super Proton Synchrotron (SPS) designed to investigate the origin of proton spin, specifically the contribution of $L_{quark}$ and $L_{gluon}$. The experiment will be using the SPS's 190 GeV pion beam and a polarized NH3 target to study the pion-induced Drell-Yan process via deep inelastic scattering. Design and construction techniques are currently being prepared to build a drift chamber that will be installed as part of the COMPASS detector. As a part of that process, two prototype drift chambers have been developed and tested in order to prepare for construction of the final drift chamber. The latest prototype is 16.5" wide by 72" long, with a total of 66 alternating field and signal wires divided among two parallel wire chambers. In order for any drift chamber to function properly and uniformly, the tensile characteristics of the wires must be measured, both before and after the wires have been soldered in the chamber. This poster will detail the methods and results of these measurements as they apply to the prototype. [Preview Abstract] |
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EA.00140: Construction of Prototype B for the COMPASS polarized Drell-Yan experiment James Mallon While there has been significant progress in the past years of understanding the quark and gluon structure of the nucleon, many important questions remain open; in particular, we have only elementary understanding of the origin of the proton spin. The COMPASS project is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton, and COMPASS ll's polarized Drell-Yan experiments will be exploring the quark angular momentum contribution to the spin of the proton. As a part of this process, two drift chambers must be constructed to replace older, faulty straw chambers. As a preliminary study, smaller prototype drift chambers were constructed, one in Saclay, France, and the other Prototype B (PTB), at the University of Illinois at Urbana-Champaign. PTB is 16.5'' wide, 72'' long, and 3.03'' tall, with 66 wires across two separate wire planes, and this poster will detail the methods used to fully assemble PTB. [Preview Abstract] |
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EA.00141: Measuring the Position Resolution of a COMPASS Drift Chamber Prototype B Rojae Wright COMPASS is a fixed target experiment at CERN in Geneva, Switzerland which investigates the quark and gluon structure of proton. The experiment will study the transverse spin- and momentum dependent quark structure for the proton through pion-induced Drell-Yan scattering off transversely polarized proton targets. The observed Sivers asymmetries are thought to be indicative of quark orbital angular momentum inside the proton. UIUC is responsible for building and designing two drift chambers to replace aging straw chamber stations in the COMPASS spectrometer. UIUC has built two drift chamber prototypes. The current prototype B has 16 anode sense wires in each of two separate planes. Cosmic rays are used to measure the position resolution of the drift chamber. This poster describes the details on the experimental method and steps that will lead to the measurement of the position resolution for the COMPASS drift chamber prototype B. [Preview Abstract] |
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EA.00142: Precision calibration of a laser displacement sensor Bradley Irvin Surface current coils with extremely precise magnetic fields can be designed using the magnetic scalar potential. These coils are constructed as curved 3-dimensional printed circuit boards with traces flowing along the equipotential contours. We are preparing to manufacture such coils using a high speed precision spindle controlled by a Staubli RX130 6 axis robotic arm. A laser displacement sensor is used to calibrate the robot and to determine the position of the circuit board substrate for accurate construction. In this poster, we describe a procedure to calibrate the laser displacement sensor to an accuracy of a few microns using linear least squares fits to the position of two coupled linear stages. [Preview Abstract] |
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EA.00143: Exploring the Collective Properties of $^{160} Gd$ using the $(n,n'\gamma )$ reaction Zachary Tully, Shelly Lesher, Ian Marsh, Ben Crider, Erin Peters, Francisco Estevez, Steven Yates, Clark Casarella, Mallory Smith, Ani Aprahamian, J.R. Vanhoy We have examined $^{160}Gd$ using the $(n,n'\gamma )$ inelastic scattering reaction to determine the collective nature of $0^{+}$excitations. Low-lying $0^{+}$excitations in deformed nuclei can be associated with quadrupole vibrations such as $\gamma $ and $\beta $ vibration. The $\gamma $-vibration occurs along the semi-major axis of the spheroidal nucleus and its decay scheme is well categorized. However the $\beta $-vibrational (quadruple major axis vibration) decays are undetermined. Because of this uncertainty, more knowledge of the collective $0^{+}$ excitations is needed. Using the $(n,n'\gamma )$ reaction as a $\gamma $-ray spectroscopy method, we probed the nucleus in two experiments at the University of Kentucky using the 7MeV Van de Graff accelerator. The first experiment was an excitation function with energies of 1.5-2.8 MeV and the second being three angular distributions with neutron energies of 1.5, 2.0 and 2.8 MeV. The excitation functions allow us to confirm and categorize the overall level scheme and by using this information, the angular distributions will be used to obtain B(E2) values and lifetimes of the levels. [Preview Abstract] |
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EA.00144: Control and Calibration of a Staubli RX130 Robotic Arm for Construction of Surface Current Coils Patrick VanMeter, Christopher Crawford, Emre Guler, Mario Fugal, Bradley Irvin Precision low energy neutron experiments require extremely uniform magnetic fields for manipulating the neutron spin. Such fields can be generated with surface current coils--precision 3-dimensional printed circuits. We are developing a facility to etch out these circuits on copper-plated curved forms using a high-speed spindle attached to the end-effector of a Staubli RX130 six-axis robotic arm. We describe our mathematical model of the robotic links and the software system we designed to control the motion of the arm and to prevent collisions during actuations. We developed a calibration procedure to achieve accuracy of 30 microns in the position of drill. [Preview Abstract] |
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EA.00145: Direct Photon Simulations for Correlation Studies in 510 GeV Proton-Proton Collisions at PHENIX Aaron White, Christine Aidala A direct photon is generated at leading order by a quantum-chromodynamics 2-to-2 hard-scattering subprocess, such as $g+q \rightarrow \gamma+q$ and $q+\bar{q} \rightarrow \gamma+g$. These subprocesses result in two products, a photon and an associated hadronic decay jet, the azimuthal distribution of which can be described by a correlation function. The direct photon produced by these subprocesses is a useful probe of the jet and initial parton momenta and energies. The PHENIX detector is located at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) and is designed to measure charged particles and photons produced by p+p, d+Au, and heavy ion collisions at variable center of mass energies ($\sqrt{s}$). Previously, the PHENIX collaboration has published the correlation function for p+p collisions at $\sqrt{s}$ = 200 GeV. Starting in 2011, data at $\sqrt{s}=510$ GeV became available from RHIC, offering the opportunity to probe parton and jet kinematics at higher energies using direct photon processes. This poster will present the results of PYTHIA/GEANT3 simulations at various center of mass energies that are needed to understand the correlation functions at higher energies. [Preview Abstract] |
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EA.00146: Simulations for the Characterization of Germanium Detectors used in the Search for Neutrinoless Double Beta Decay Asher Wasserman, Chris O'Shaughnessy, John Wilkerson An open question in physics is whether neutrinos have the properties of Majorana or Dirac fermions; that is, are neutrinos their own antiparticles or not? A discovery of neutrinoless double beta ($0\nu\beta\beta$) decay would prove that neutrinos are indeed Majorana fermions. The \textsc{Majorana} Collaboration is searching for $0\nu\beta\beta$ decay in $^{76}$Ge, for which single beta decay is energetically forbidden and the Standard Model allowed $2\nu\beta\beta$ decay has been observed. Tonne scale experiments aim to have a sensitivity to half lives in the range of $10^{26}$-$10^{27}$ years, corresponding to just a few counts per tonne-year in the region of interest (ROI). The goal is to minimize background in the ROI to 1 count per tonne-year. To help achieve this level of sensitivity it is important to understand the precise response of the detectors. For this purpose, a characterization stand was constructed to expose the detectors to known radioactive sources in a well-understood geometry. By building a Monte Carlo simulation of this apparatus in Geant4 it is possible to gain an understanding of the detector's response to backgrounds, so that such events may be efficiently rejected from the data set. This poster addresses the simulation of the characterization stand. [Preview Abstract] |
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EA.00147: Data Acquisition Visualization Development for the MAJORANA DEMONSTRATOR Laura Wendlandt, Mark Howe, John Wilkerson The M{\sc ajorana} Project is building an array of germanium detectors with very low backgrounds in order to search for neutrinoless double-beta decay, a rare process that, if detected, would give us information about neutrinos. This decay would prove that neutrinos are their own anti-particles, would show that lepton number is not conserved, and would help determine absolute neutrino mass. An object-oriented, data acquisition software program known as ORCA (Object-oriented Real-time Control and Acquisition) will be used to collect data from the array. This paper describes the implementation of computer visualizations for detector calibrations, as well as tools for more general computer modeling in ORCA. Specifically, it details software that converts a CAD file to OpenGL, which can be used in ORCA. This paper also contains information about using a barium-133 source to take measurements from various locations around the detector, to better understand how data varies with detector crystal orientation. [Preview Abstract] |
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EA.00148: Dead Layer Surface Distribution Analysis of a Broad Energy Germanium Detector Ari Zitin The implantation of the Li\textsuperscript{+} contact on the surface of germanium detectors leaves a dead layer on the germanium crystal where ionizing radiation does not produce charge collection in the germanium crystal. In order to characterize this dead layer, an \textsuperscript{241}Am source was used to scan the surface of the detector in a 90 point grid. The counts in the \textsuperscript{241}Am peak were extracted at each grid point and this information was used to explore the deviations in the dead layer as a function of the position of the source over the germanium crystal. This initial experiment does not reveal the actual surface distribution of the dead layer in terms of thickness, but future work with simulations and an additional scan with a \textsuperscript{133}Ba source will allow a more quantitative analysis of the surface distribution of the dead layer on the germanium crystal. This work will be used by the \textsc{Majorana} collaboration to characterize the modified broad energy germanium detectors that will be used in the \textsc{Majorana Demonstrator}. [Preview Abstract] |
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EA.00149: Characterizing of a new Mesytec MADC-32 in comparison with NIM standard ORTECMCA(Module{\#} 927) Armen Gyurjinyan, Roza Avetisyan, Wanpeng Tan, Ani Aprahamian We compare two different types of ADC modules with respect to resolution. In Gamma-Ray spectroscopy, some of the best ADCs used are the NIM ORTEC APEC-927 ADCs.This ADC has a maximum resolution of 16K and costs on the average of 10000{\$}. And yields an energy resolution for 1.6 keV at 1 MeV. We have tested and characterized a much cheaper Mesytec MADC with 32 channels in comparison the ORTEC dual Aspec-927 module.152Eu calibration source was used to get data simultaneously from a 109{\%} efficiency Ge detector.RadWare was used to analyze both spectra and look at the resolutions of the ADCs as a function of energy, as well as the linearity. We found very insignificant differences between the two types of ADCs enabling us to use much cheaperelectronics modules to get data of nearly equal quality. [Preview Abstract] |
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EA.00150: Effects of energy straggling in timing detector foils on mass resolution of the St. George detector system Jacques Laurence, Luis Morales, Sunil Kalkal, Jerry Hinnefeld, Hyo Soon Jung, Manoel Couder Many questions remain regarding nucleosynthesis during stellar helium burning. The recoil mass separator St. George at the University of Notre Dame has been designed to investigate low energy $(\alpha, \gamma)$ reactions for heavy ions in inverse kinematics to answer such questions. St. George is expected to achieve beam suppression of the order $\ge$ $10^{15}$ by the time the beam and reaction products reach the detection system, but further background reduction of unreacted beam particles is required in the detection system itself. Indiana University South Bend, in collaboration with Notre Dame, has developed a detection system for St. George that takes advantage of energy and timing measurements to differentiate recoiling reaction products from the much more abundant unreacted beam. The timing detection system requires beam and recoil products to pass through two thin foils before energy measurements are made with a silicon detector, and energy straggling in these foils can degrade the mass resolution of the detection system. The Geant4 toolkit has been used to construct a simulation of the St. George detection system to investigate the effects on mass resolution of energy and position straggling of unreacted beam and reaction products through various foil materials. [Preview Abstract] |
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EA.00151: Timing resolution and detection efficiency of the St. George detector system Luis Morales, Jacques Laurence, Sunil Kalkal, Jerry Hinnefeld, Hyo Soon Jung, Manoel Couder The St. George recoil mass separator at the University of Notre Dame will be used to study $(\alpha , \gamma)$ reactions of astrophysical interest. A detection system was developed for the St. George recoil mass separator by Indiana University South Bend that will utilize energy and time-of-flight to separate reaction products from residual unreacted beam particles. The detection system utilizes two transmission detectors in which secondary electrons produced by the passage of an ion through a thin foil are deflected by electric and magnetic fields onto a microchannel plate (MCP) detector, which registers timing measurements. A silicon strip detector is used to measure the ion's kinetic energy. Measurements were conducted with an alpha source of Am-241 and Gd-148 to determine the MCP efficiency and timing resolution. The best values achieved to date are 75\% for efficiency and 550 ps for timing resolution. The program SIMION was used to investigate further the effect of varying the voltages applied to the foil, the field-shaping electrodes, and the MCP detector, on the efficiency and timing resolution. [Preview Abstract] |
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EA.00152: Double Folding Analysis of $^{6}$Li Elastic and Inelastic Scattering on $^{208}$Pb B. Pineyro, J.T. Matta, D. Patel Nuclear incompressibility is an important parameter of the nuclear equation of state; but, it is not well constrained. The Isoscalar Giant Monopole Resonance (ISGMR), a compressional mode of the nucleus, can be used to probe nuclear incompressibility. Radioactive Ion Beam (RIB) facilities are becoming more common thus it would be interesting to measure ISGMR energies and strength distributions far from stability. In inverse kinematics the most appropriate solid target probe is $^{6}$Li because it is light, T$=$0, and can be made thin enough for recoils to escape. Given the paucity of information of $^{6}$Li as an ISGMR probe, a measurement of the $^{208}$Pb ISGMR was performed at RCNP, Osaka University, Japan with $^{6}$Li at 60 MeV/A. Elastic scattering and small angle inelastic data were obtained. Optical model parameters were acquired by fitting the elastic data and used to extract the energy and strength distribution of the ISGMR via a multipole decomposition analysis. [Preview Abstract] |
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EA.00153: Characterization of the deuterated scintillator EJ-315 for neutron energies from 5-30 MeV Jay Riggins, Michael Febbraro, Frederick Becchetti, Ramon Torres-Isea, Alan Howard, Christopher Lawrencew, James Kolata Deuterated scintillator neutron detectors have shown to give superior performance in applications including nuclear reaction studies and homeland security. Characterization of the response of such deuterated detectors is needed for further determination of suitable applications. In particular the asymmetry of the (n$+$d) differential cross section, in comparison to the differential (n$+$p) cross section, allows for spectrum unfolding to extract information on the incident neutron energy spectra without need for time-of-flight. Characterization of the deuterated-benzene scintillator EJ-315 has been conducted at the Institute for Structure and Nuclear Astrophysics at the University of Notre Dame. Pulse shape discrimination (PSD), light response, detector resolution, and intrinsic efficiency have been measured via (d,n), and ($^{3}$He,n) reactions. The applications to stable and exotic beam reactions involving neutron physics, as well as homeland security regarding the detection of special nuclear materials will~be presented. [Preview Abstract] |
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EA.00154: Propagation of Light through Composite Dark Matter Audrey Kvam, David Latimer A concordance of observations indicates that around 80\% of the matter in the universe is some unknown dark matter. This dark matter could be comprised of a single structureless particle, but much richer theories exist. Signals from the DAMA, CoGeNT, and CDMS-II dark matter detectors along with the non-observation of dark matter by other detectors motivate theories of composite dark matter along with a ``dark'' electromagnetic sector. The composite models propose baryon-like or atom-like dark matter. If photons kinetically mix with the ``dark'' photons, then light traveling through dark matter will experience dispersion. We expect the dispersion to be approximated by the Drude-Lorentz model where the model parameters are particular to a given dark matter candidate. As light travels through the dispersive medium, it can accrue to a frequency-dependent time lag. Measurement of such a time lag can yield clues as to the nature of the dark matter. As a first application, we model hydrogenic dark atoms and use astrophysical data to constrain the mass, binding energy, and the fractional electric charge of the dark atoms. [Preview Abstract] |
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EA.00155: Characterization and Removal of Deposited Surface Contamination on Materials for Use in Low-Background Environments Alex Larson, Muhammad Khizar, Dongming Mei Materials used in Low-Background experiments, such as PTFE and Germanium crystals, require high levels of cleanliness to avoid false positives and noise in experiments. The storage and standard process of preparing these materials for use causes this contamination, such as organic material from photoresist treatment of germanium samples or dust from the environment. The purpose of this study is to determine the most effective way to remove these surface contaminants from the materials through the development of certain procedures for use with each material. The procedures use a combination of treatment techniques involving the use of acids, bases, oxidizers, and solvents. These different procedures target certain contaminants, such as removing surface grease and oxidizing and removing organic films. Testing the different procedures with contaminated samples of material and analyzing the result yields the most cost and time effective methods for cleaning these materials. The number of particles counted on the surface before and after the cleaning procedure determines the effectiveness of the procedure for a given material. In this project I have discovered a method that can reach near 100{\%} particulate removal from PTFE for levels of contamination from a normal lab environment. [Preview Abstract] |
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EA.00156: Stabilization of a 30 keV Proton Source Nicholas Roane, Stefan Baessler, Americo Salas, Carl Whitaker, Aaron Ross Our group has constructed a small accelerator as a stable, low-intensity source of 30-keV protons to characterize the detection efficiency of a large-area, thick, 127-hexagonal segmented silicon detector, which we will in the Nab experiment at SNS, Oak Ridge National Laboratory. Accelerated electrons emitted from a tantalum cathode ionize residual gas at a pressure of 10$^{-8}$-mbar, producing H$^{+}$ (protons) and H$_{2}^{+}$ which we accelerate across 30 kV. A bending magnet separates the ion species into two beams which are detected in the present setup with separate microchannel plate detectors. For detector efficiency studies of the silicon detector, we require correlation between and minimal fluctuation in the ion beam intensities. We will present our efforts toward configuring an accelerator system with these characteristics. [Preview Abstract] |
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EA.00157: Shimming of a Magnet for Calibration of NMR Probes for the Muon g-2 Experiment Rachel Bielajew The Muon g-2 Experiment at Fermilab aims to measure the anomalous magnetic moment aµ ? (g-2)/2 of the muon to the precision of 0.14 parts per million. This experimental value of aµ can then be compared to the similarly precise theoretical predictions of the Standard Model in order to test the completeness of the model. The value of aµ is extracted from muons precessing in a magnetic field. The magnetic field will be measured with a set of 400 Nuclear Magnetic Resonance (NMR) probes, which have the ability to measure the field to a precision of tens of parts per billion. NMR probes will be tested using a 1.45 Tesla magnet at the University of Washington Center for Experimental Nuclear Physics and Astrophysics (CENPA). In order to achieve a significant signal from NMR probes, the magnetic field in which the probes are immersed must be extremely uniform. The existing magnet at CENPA has an approximately linear gradient in magnetic field of about 1 Gauss per centimeter in the smoothest direction. A pair of adjacent square Helmholtz coils was designed and built to create a linear gradient in order to cancel the existing gradient. The length of the NMR signals improved with the implementation of the coils. The results of the addition of the coils to the magnet on the signals from the NMR probes will be presented. [Preview Abstract] |
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EA.00158: Measurements of photon scattering lengths in scintillator and a test of the linearity of light yield as a function of electron energy Alexandra Huss The SNO$+$ experiment in Sudbury, Canada will utilize approximately 800 tons of liquid scintillator in an attempt to detect neutrinoless double beta decay and measure solar neutrinos and geoneutrinos. The type of particle that interacted with the scintillator yields information about the emitted time spectrum of photons. The ability to detect this time dependency may depend on the scattering length of the photon because a photon's path to a light detector is less predictable if its scattering length is short compared to the distance it traveled before detection. In order to determine the energy of an interacting particle, it is also necessary to determine the relationship between light yield and energy. This relationship is tested by measuring the light output of electrons at very low light intensities. It is found that there is a change in linearity for electron energies at 0.4MeV. I will discuss the measurements made to test the linearity of light yield versus electron energy and measurements made to determine the scattering length of photons in scintillator samples. [Preview Abstract] |
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EA.00159: Germanium Detector Crystal Axis Orientation for the MAJORANA Demonstrator Hannah LeTourneau The MAJORANA Demonstrator, currently being constructed at Sanford Underground Research Facility in Lead, South Dakota, is an array of germanium detectors which will be used to search for neutrinoless double beta decay, which would demonstrate that neutrinos have a Majorana mass term and lepton number is not conserved. An important characteristic of semiconductor detectors is the crystal axis orientation, because the propagation of electromagnetic signals is attenuated by the location of the interaction relative to the axis of the crystal. Conventionally, a goniometer is used to position a collimated low energy gamma source in many small increments around the detector to measure the rise time at each position. However, due to physical constraints from the casing of the Demonstrator, a different method must be developed. At the University of Washington this summer, I worked with a $^{76}Ge$ point-contact detector. I found the crystal axis orientation first with Americium 241, a lower energy gamma source. Then, I used a higher energy source, Thorium 232, in conjunction with the only a few angular reference points to also calculate rise time. Also, I wrote code to process the data. The success of this method will be evaluated and discussed. [Preview Abstract] |
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EA.00160: Mapping the Gain Stability of Multi-Pixel Photon Counters for the Muon g-2 Calorimeters Kazimir Wall The Fermilab Muon g-2 collaboration identified Hamamatsu Multi-Pixel Photon Counters (MPPCs, or SiPMs) as an excellent candidate for the PbF$_{\mathrm{2}}$ calorimeter light readout. These devices are new to particle physics and the University of Washington Muon Group is evaluating them extensively. To be selected for the g-2 experiment the MPPCs must pass stringent gain stability requirements. For events where particles arrive close in time the detector exhibits a decrease in gain for the second particle. This effect is due to the inherent pixel recovery time of the MPPC. It is deterministic and can be corrected for. The work presented here is a study of the gain decrease of the second particle to be used as a systematic correction. In the laboratory, the two-pulse effect is simulated by splitting the output of a 407nm pulsed diode laser into two channels. One of these channels is then delayed by a variable amount in the range of 5ns to 160ns. The output of the SiPM is digitized using a DRS4 chip developed at PSI, Switzerland. By observing the two pulses independently as well as together the gain change on the second pulse can be mapped. The quantified result is the function G2($\Delta $t, E$_{\mathrm{1}}$, E$_{\mathrm{2}})$ where $\Delta $t is the difference in time of the two pulses and E$_{\mathrm{i}}$ is the energy of the i$^{\mathrm{th}}$ pulse. [Preview Abstract] |
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EA.00161: Experimental design for an isomer depletion experiment on $^{\mathrm{108m}}$Ag via fast neutron reactions Brian Goddard, James Carroll, Noel Guardala, Marc Litz, Sarkis Karamyan The nuclide $^{108}$Ag is unstable with a ground-state half-life of 2.38 min, and primarily $\beta^{-}$ decays to $^{108}$Cd. Interestingly, the isomer $^{\mathrm{108m}}$Ag has a substantially longer half-life of 438 years due to its high spin (J $=$ 6) at modest energy (110 keV). This nuclide, with such a long isomeric lifetime and relatively short ground-state lifetime, is an excellent candidate for study as a potential medium for long-term energy storage. The key to extracting this energy is the ability to deplete part of the population held in the isomer state by exciting it to a higher-lying intermediate state that has a greater probability of transitioning toward the ground state. Isomer depletion for $^{\mathrm{108m}}$Ag has been successfully demonstrated at ARL using bremsstrahlung to excite intermediate states (AIP Conf. Prod. 1525, 586, 2013). The present experiment will investigate depletion of $^{\mathrm{108m}}$Ag via irradiation by fast neutrons at the NSWCCD accelerator facility -- the initial phase will use neutrons near 500 keV from the $^{7}$Li(p, n) reaction, so that only (n, n') reactions are expected. This poster will discuss the background, theory, and experimental design for this experiment, including the construction of a customized sample transport system and automated control utilizing LabVIEW. [Preview Abstract] |
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EA.00162: Measuring Azimuthal Angular Resolution in $p^{\uparrow}+p\to jet+X$ and $p^{\uparrow}+p\to jet+\pi^{\pm}+X$ at $\sqrt{s}=500$ GeV at STAR Jacob Long Measurements of particle production from polarized-proton collisions at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) give insight into proton spin structure. One way to study spin effects such as those due to quark transversity or the Sivers parton distribution function is to analyze spin-dependent asymmetries in the final-state particles produced in transversely polarized-proton collisions. The large angular acceptance of the Solenoidal Tracker at RHIC (STAR) allows the reconstruction of full jets in addition to inclusive hadron production. Analyzing spin-dependent azimuthal asymmetries in $p^{\uparrow}+p\to jet+X$ and $p^{\uparrow}+p\to jet+\pi^{\pm}+X$ allows one to isolate contributions from the Sivers and Collins effects. Measuring the resolution of the relevant azimuthal angles is critical to quantifying the systematic uncertainties of the asymmetry measurements. A useful means to study the resolutions and response of the STAR detector in light of pile-up backgrounds is to embed simulated events into real zero-bias data. In 2009 and 2011 STAR collected data from polarized-proton collisions at $\sqrt{s} = 500$ GeV. These samples provide an opportunity to study the angular resolution of inclusive jets at 500 GeV from embedded simulated events, and t [Preview Abstract] |
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EA.00163: Using $\pi^{0}$'s to Understand Proton Spin Structure through Polarized p+p Collisions at $0.8 < \eta < 2.0$ and $\sqrt(s) = 200$ GeV at STAR Stephen Place Measurements of spin dependent observables at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory provide unique insight into the contribution of a proton's constituents to its spin. The Solenoidal Tracker at RHIC (STAR) can be used to measure effects of the quark and gluon spins in the proton by observations of neutral pions that result from longitudinally and transversely polarized proton-proton collisions in STAR. The neutral pions ($\pi^{0}$'s) decay into two photons that, for $0.8 < \eta < 2.0$, can be observed in the endcap electromagnetic calorimeter in STAR. These are used to reconstruct the kinematic properties of the $\pi^0$'s and we can then look for spin asymmetries in $\pi^{0}$ production. Measurements of both the longitudinal and transverse spin asymmetries in the production of $\pi^0$'s from data taken in 2006 have made some contributions to our understanding of the structure of the proton. New data taken in 2009, in a longitudinal spin run with greater luminosity, will provide greater precision to the final results. Results from 2006 and preliminary work on 2009 data will be shown. [Preview Abstract] |
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EA.00164: Generating a ``Clean'' Sample of $\pi^{\mathrm{0}}$'s and $\eta $'s for Energy-Calibrating the STAR Endcap Calorimeter Lauren Skiniotes The Solenoidal Tracker at RHIC (STAR) detector, located at Brookhaven National Laboratory, utilizes polarized-proton collisions to explore the contributions made by sea quarks and gluons to the known proton spin. An important component of STAR is the Endcap Electromagnetic Calorimeter (EEMC), which detects, among other particles, photons produced in the pseudorapidity range 1 \textless $\eta $ \textless 2 from beam-beam collisions and measures their energy. The quality of these energy measurements depends on accurately calibrating the energy response of the EEMC. STAR has used minimum-ionizing particles (MIPs) for this calibration. An independent energy calibration method uses reconstructed neutral pions ($\pi^{\mathrm{0}})$ and etas ($\eta )$ obtained, ideally, from a ``clean'' event sample with minimum contamination from background. By refining sample selection criteria, background is reduced, thus leaving a ``clean'' sample of $\pi^{\mathrm{0}}$'s and $\eta $'s. These ``clean'' samples will be used to verify the energy calibration of the EEMC obtained using MIPs. [Preview Abstract] |
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EA.00165: Relative Yields of $^{149-153}$Pr in Spontaneous Fission of $^{252}$Cf Jonathan Eldridge, Enhong Wang, J.K. Hwang, Joe Hamilton, A.V. Ramayya, Y.X. Luo, J.O. Rasmussen, S.J. Zhu, S.H. Liu, G.M. Ter-Akopian, Yu. Ts. Oganessian The relative yields of the fission partners of $^{149-153}$Pr, resulting from the spontaneous fission of $^{252}$Cf, were studied. This study was done by means of $\gamma -\gamma -\gamma $, and $\gamma -\gamma -\gamma -\gamma $ coincidence data taken in 2000 by the multi-HPGe, Compton-suppressed, gamma detector array, Gammasphere, at Lawrence Berkeley National Lab. The coincidence data were analyzed by double- and triple-gating on transitions in $^{149-153}$Pr and obtaining the intensities of the $^{93-101}$Y transitions. For $^{150,151,152,153}$Pr the 3n channel was found to be the strongest. The $^{149}$Pr, however, was found to peak at the 4n channel. These results were used to verify the assignments of the level schemes of $^{151,152,153}$Pr [1-3]. The data are found to be in agreement with Wahl's independent yield tables [4]. \\[4pt] [1] E. Wang et al., Bull.Am.Phy.Soc.DNP Oct. 2013\\[0pt] [2] J. H. Hamilton et al., Bull.Am.Phy.Soc.DNP Oct. 2013\\[0pt] [3] E. Wang et al., BAPS, SESAPS, 11/13.\\[0pt] [4] A. C. Wahl, Atomic Data and Nuclear Data Tables, Vol. 39, No. 1, May 1988, Table XVI. [Preview Abstract] |
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EA.00166: Model independent extraction of the axial mass parameter in CCQE anti neutrino-nucleon scattering Heather Grebe Neutrino oscillation studies depend on a consistent value for the axial mass. For this reason, a model-independent extraction of this parameter from quasielastic (anti)neutrino-nucleon scattering data is vital. While most studies employ a model-dependent~extraction using the dipole model of the axial form factor, we present a model-independent description using the z expansion of the axial form factor. Quasielastic antineutrino scattering data on C-12 from the MiniBooNE experiment are analyzed using this model-independent description. The value found, m$_A = 0.85^{+0.13}_{-0.06} \pm 0.13$ GeV, differs significantly from the value utilized by the MiniBooNE Collaboration, m$_A = 1.35$ GeV. [Preview Abstract] |
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EA.00167: Environmental Radioactivity: Gamma Ray Spectroscopy with Germanium detector Gargi Vyas, Cornelius Beausang, Richard Hughes, Thomas Tarlow, Kristen Gell A CF-1000BRL series portable Air Particle Sampler with filter paper as filter media was placed in one indoor and one outdoor location at 100 LPM flow rate on six dates under alternating rainy and warm weather conditions over the course of sixteen days in May 2013. The machine running times spanned between 6 to 69 hours. Each filter paper was then put in a germanium gamma ray detector, and the counts ranged from 93000 to 250000 seconds. The spectra obtained were analyzed by the CANBERRA Genie 2000 software, corrected using a background spectrum, and calibrated using a 20.27 kBq activity multi-nuclide source. We graphed the corrected counts (from detector analysis time)/second (from air sampler running time)/liter (from the air sampler's flow rate) of sharp, significantly big peaks corresponding to a nuclide in every sample against the sample number along with error bars. The graphs were then used to compare the samples and they showed a similar trend. The slight differences were usually due to the different running times of the air sampler. The graphs of about 22 nuclides were analyzed. We also tried to recognize the nuclei to which several gamma rays belonged that were displayed but not recognized by the Genie 2000 software. [Preview Abstract] |
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EA.00168: Characteristisation of a new multiple channel analyzer - linearity Roza Avetisyan, Armen Gyurjinyan, Wanpeng Tan, Ani Aprahamian Due to the large difference~ in purchasing value of a new 32 channel Mesitec ADC and more traditional ADCs, we tested the non-linearity properties of a 32 channel ADC in order to determine its potential use with our Ge array of detectors (GEORGINA). We used a single 109{\%} efficiency germanium (Ge) detector to obtain a $\gamma $-ray spectrum from a calibration source of 152Eu. We checked the linearity against voltage for 32 separate settings. With a linear fit, we get a non-linearity range of 0.6keV over 100-1400keV energy range. This non-linearity reduces to 0.1keV with a second order fit over the same range of energy. This level of non-linearity makes the module useful and usable for $\gamma $-ray spectroscopy. [Preview Abstract] |
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EA.00169: Measurement of the $^{19}$F($\alpha$,n) Cross Section for Nuclear Safeguards Science C.S. Reingold, J.A. Cizewski, S. Burcher, B. Manning, W.A. Peters, R.R.C. Clement, D.W. Bardayan, M.S. Smith, E. Stech, S. Strauss, W.P. Tan, M. Wiescher, M. Madurga, S. Ilyushkin A precise measurement of the $^{19}$F($\alpha$,n) cross section will improve Non Destructive Assays (NDA) of UF$_{6}$ and other actinide-fluoride samples via neutron detection techniques. We will determine the cross section with two complementary approaches. First, we will bombard a LaF$_{3}$ target with a pulsed $^4$He beam from the Notre Dame FN tandem accelerator; second, we will send a fluorine beam from the ORNL tandem through a pure helium gas target. The neutron spectra from both of these reactions will be measured using the Versatile Array of Neutron Detectors at Low Energy (VANDLE), and coincident $\gamma$ rays with a HPGe detector. We report here on data taken with VANDLE and a HPGe detector on a LaF$_{3}$ target. My poster outlines the motivation for this experiment, explains the stages of this experiment, the current experimental setup, and preliminary data. [Preview Abstract] |
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EA.00170: Universality of Hadronization Condition at RHIC and LHC Michal Petran, Johann Rafelski The hadronization analysis within non-equilibrium SHM has shown that across RHIC and LHC energy range, and across a wide range of centrality we find a universal intensive hadronization conditions of the particle source: pressure $P_h\simeq 80$MeV/fm$^3$, energy density $\varepsilon_h\simeq 0.5$GeV/fm$^3$ and entropy density $\sigma_h\simeq 3.3$fm$^{-3}$. The parameters varying as a function of reaction energy and/or centrality are source volume $dV/dy$ and strangeness saturation $\gamma_s$. This discovery allows to simplify the SHM approach: the principle of Universal Hadronization reduces the number of parameters within the non-equilibrium SHM. Two suffice at LHC and three are enough at RHIC to fully characterize all hadron production. We show this using the SHARE program: we prescribe the intensive properties of the fireball, and fit at LHC $dV/dy$, $\gamma_s$ as a function of centrality, while at RHIC we must also introduce baryon--antibaryon asymmetry $\mu_B$, where $\mu_S$ is fixed by $< s >=< \bar s >$. The other SHM parameters e.g. $T,\ \gamma_q$, are an output of this procedure, which works for all hadrons. The convergence for the most central collisions of $s/S\to 0.03$ confirms strangeness chemical equilibration in the deconfined QGP fireball hadron source. [Preview Abstract] |
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EA.00171: Design of the SUPERB Recoil Separator Zachary Jackson, Lisa Carpenter, Matt Amthor The reaccelerator ReA12 upgrade planned at the National Superconducting Cyclotron Lab (NSCL) at Michigan State University will produce higher energy rare isotope beams close to the neutron and proton drip lines. We present one option for the recoil separator which aims to take full advantage of the new capabilities of ReA12 in studying rare isotopes. The Separator for Unique Products of Experiments with Radioactive Beams (SUPERB), patterned after the second half of the Super Separator-Spectrometer (S$^{3})$ currently under construction at the Grand Acc\'{e}l\'{e}rateur National d'Ions Lourds (GANIL). This design includes both electric and magnetic dipoles and this will allow physical separation by mass-to-charge ratio (m/q) with a maximum solid angle of 26msr and a maximum magnetic rigidity of 1.44Tm. This design also allows for flexibility of optical modes. Both large acceptance and unit magnification modes will be presented. Also, a fully magnetic configuration is considered that would eliminate the expected electric rigidity limit of 10MV and increase the maximum magnetic rigidity to 1.92Tm. We will present optical designs and simulations of SUBERB developed in the code COSY Infinity including a first order system and a higher order Monte Carlo calculation simulating $^{100}$Sn production. [Preview Abstract] |
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EA.00172: Applicability of Parallel Computing to Partial Wave Analysis Justin Ruger, Gerard Gilfoyle, Dennis Weygand Bound states of Quantum Chromodynamics (QCD) give insights into the nature of confinement, a key element of the strong interaction. States may be identified from weak signals extracted from the analysis of high statistics data from reactions with many final state particles. One of the best tools for the analysis of these reactions is Partial Wave Analysis (PWA). PWA transforms an ensemble of experimental data from a large acceptance detector from free particle eigenstates to angular momentum eigenstates. The PWA program must be fast enough to deal with the large amounts of data available currently, as processing time scales with the number of events. The scope of this research is to study the applicability and scalability of Intel's Xeon Phi using the Many Integrated Core (MIC) architecture when applied to the existing PWA code at Jefferson Laboratory. An algorithm was developed for the Xeon Phi and scaled across 240 available threads, giving parallel functionality to the PWA which was originally written serially. This scaling can make the fitting process fifteen times faster. [Preview Abstract] |
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EA.00173: Validating the Analysis Algorithms to Extract the Helicity Asymmetry in the $^2{\rm H}(\vec e,e^\prime p)n$ Reaction Liam Murray, Gerard Gilfoyle Nuclei can be described with hadronic degrees of freedom (proton and neutrons), but we know these hadrons are built of quarks and gluons. We expect new phenomena at higher energy to reveal this underlying quark-gluon structure. To understand quantitatively the transition between these descriptions we need a firm understanding of the hadronic model. The structure functions are an essential meeting ground of theory and experiment. We have measured the helicity asymmetry related to the imaginary part of the longitudinal-transverse (LT) interference term of the quasi-elastic $^2{\rm H}(\vec e,e^\prime p )n$ reaction at an electron beam energy of 2.6 GeV. The measurements were made with the CLAS detector at Jefferson Lab. This structure function has not been measured in this region before. To validate our results we tested the analysis in simulation. After fitting the measured helicity asymmetry $A_{LT}^\prime$, we incorporated the fit results into the CLAS Monte Carlo simulation. We simulated both the normal and reversed torus polarities of CLAS used in the experiment. We performed the same analysis used to measure $A_{LT}^\prime$ on the simulated events. The helicity asymmetry extracted from the simulation was consistent with the input taken from the measured $A_{LT}^\prime$. [Preview Abstract] |
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EA.00174: Static quadrupole moments and B(E2)'s in N=Z nuclei $^{88}$Ru, $^{92}$Pd, and $^{96}$Cd in shell model calculations Larry Zamick, Shadow Robinson, T. Hoang, Yitzhak Sharon, Alberto Escuderos We calculate B(E2)'s and quadrupole moments Q(J) in the even-even N=Z nuclei ($^{88}$Ru,$^{92}$Pd and $^{96}$Cd) in the model space p$_{3/2}$, f$_{5/2}$, p$_{1/2}$, and g$_{9/2}$. We use 2 interactions( jj44b, jun45). For the J=0$^{+}$ ground states the occupations of the lowest configuration i.e. the one with least g$_{9/2}$ occupancy are quite different for the 2 interactions-((1.6,7.4), (9.7,28.8) and (49.6,58.8)). To the extent that one can make a collective associatkon with the shell model it appears that in this model space $^{88}$Ru is strongly oblate, $^{92}$Pd is vibrational and $^{96}$Cd is prolate. The values of B(E2, J$\rightarrow$ J-2) (e$^{2}$ fm$^{4}$) and Q(J) (e fm$^{2}$ ) using jj44b for J=2,4,6,8,10 are $^{88}$Ru B(E2) (578,843,972,1056, 1107) and for Q(J) (28.0,37.1,45.5,49.5,51.1). The positive Q (2$^{+}$ ) is indicative of oblateness. $^{92}$Pd B(E2) (366, 498, 465, 283, 344) and for Q(J) (4.8,11.1,24.0,33.8,40.0) . In the harmonic vibrational limit Q(2$^{+}$ ) is zero. Here it is small. $^{96}$Cd B(E2) (155, 206, 187, 71, 81 and for Q(J) (-16.4,-15.2,-2.4, +37.6, +24.0 ) . Note the change in sign from J=6 to J=8 and 10. [Preview Abstract] |
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EA.00175: Resolution Performance of HERA-B Lead-Glass Calorimeters Anthony Losada, Edward Brash, Jordan Thomas, Carlos Ayerbe-Gayoso, Matthew Burton, Charles Perdisat, Mark Jones, Vina Punjabi, Carsten Hast, Zenon Szalata In preparation of upcoming 12GeV experiments at Thomas Jefferson National Accelerator Facility it is necessary to upgrade existing systems or install new detectors. As part of this effort, an array of lead-glass sampling calorimeters is need for use in the GEP-5 experiment. A sampling calorimeter can be used to determine the energy and spatial position of a high energy particle that enters it while simultaneously stopping the particle. To determine the appropriate construction to meet the needs of upcoming experiments, it was necessary to take an existing model and confirm its energy and position resolution. This model could then be confirmed as an option for the final construction, or used as a starting point to design a better detector. For our test we obtained ten lead-glass calorimeters used in HERA-B and tested them in End Station A at SLAC. I will report on our findings for the HERA-B lead-glass sampling calorimeters. I will cover the results of both the energy and position resolutions as well as the methods used to determine these quantities. [Preview Abstract] |
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