Bulletin of the American Physical Society
2011 Fall Meeting of the APS Division of Nuclear Physics
Volume 56, Number 12
Wednesday–Saturday, October 26–29, 2011; East Lansing, Michigan
Session EA: Conference Experience for Undergraduates Poster Session (2:00-4:00PM) |
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Room: Big Ten C |
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EA.00001: Beta Decay Q value Measurements for Astrophysics Brittany Abromeit, Sean Liddick, Scott Suchyta, Nicole Larson, Murali Bolla The rapid neutron process is responsible for the creation of approximately half of the neutron-rich heavy elements above iron. The path of the r-process depends sensitively on the nuclear masses of the isotopes involved. R-process calculations use masses extracted from global theoretical models. To better constrain the r-process path, the beta-decay of neutron-rich nuclei are studied. The beta-decay Q value can be extracted from a measurement of the beta-decay electron energy distribution, providing the relative mass between the parent and daughter isotope. The NSCL has a successful beta-decay spectroscopy station consisting of multiple segmented 1-mm thick silicon detectors. To determine the sensitivity of the system for beta-decay Q value the system was simulated with Geant4 and compared with a measurement of five 1-mm thick silicon detectors and a pure beta emitter, 90Sr. The comparison between the experimental and simulated beta-decay spectrum, as well as the outlook for Q value measurements with the device, will be presented. [Preview Abstract] |
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EA.00002: Optimizing fits of Geant4 simulations to measured gamma-ray spectra on a parallel computing cluster Michael Agiorgousis We have developed software to find the best fit between simulated and measured gamma-ray spectra, by varying the energies of the gamma rays and the lifetimes of the states that they de-excite. Using a grid search algorithm based on a chi squared analysis, we identify the energies and lifetimes that provide the best fit. Separate simulations of each energy lifetime pair must be run, each requiring a significant amount of computing resources, so we implemented the Ursinus College parallel computing cluster. The software can be used with simulations of any detector system, but in the present work, we consider Geant4 simulations of the CAESAR array at the NSCL. [Preview Abstract] |
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EA.00003: A new method to study the resonances in the 12C+12C fusion reaction Adam Alongi The $^{12}$C + $^{12}$C nuclear fusion reaction is an important part of the reaction processes which power large stars and create heavier elements. The fused nuclei form an excited $^{24}$Mg nucleus which can decay by emitting a proton, neutron, or alpha particle as well as gamma rays. The proton channel was experimentally studied at lab energies of 8.2MeV using a thick target. Preliminary data analysis showed that the Q-value spectrum of the p1 channel is broader than the other proton channel, indicating the existence of a resonance at lower energy. To understand the abnormal shape of the Q-value spectrum, a detailed simulation using the Geant4 code was developed to reproduce the experimental results. By comparing the simulation results with the observed Q-value spectrum, the parameters of the resonance in the p1 channel are determined. This new technique will provide a more efficient way to search for resonances in the $^{12}$C + $^{12}$C fusion reaction at lower energies. [Preview Abstract] |
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EA.00004: Electronics and Data Acquisition for MiniLENS M. Amrit, J. Blackmon, C. Rasco, L. Afanasieva The Low-Energy Neutrino Spectroscopy (LENS) Collaboration aims to precisely measure the entire energy spectrum of solar neutrinos through charged-current neutrino interactions using indium-loaded scintillator in a novel, optically-segmented detector architecture. The collaboration is currently constructing prototype detectors, aiming towards a 1 m$^3$ prototype, miniLENS, that will demonstrate the performance and selectivity of the full-scale LENS instrument. Here we present the electronics and data acquisition system that we are developing for miniLENS. The responses of smaller (up to 15 liter) prototype detectors have been studied to characterize the combined response of the scintillator and detector architecture. We have studied various approaches for triggering and for combining signals from multiple photomultipliers to help design an acquisition system best suited to fully characterize the performance of the miniLENS prototype in a cost-effective manner. Analysis of our current prototype measurements and the design of the data acquisition system for miniLENS will be presented. [Preview Abstract] |
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EA.00005: Development of Veto Detector for MiniCLEAN Experiment to Aid in the Search for Dark Matter Matthew Anthony Weakly Interacting Massive Particles (WIMPs), the leading candidate for dark matter, are theorized to comprise approximately 83{\%} of all of the matter in the universe. MiniCLEAN is a single phase liquid argon detector searching for a direct signal from WIMPs elastically scattering in its fiducial volume. These interactions are extremely rare (only several per year) so a high efficiency veto detector must distinguish between dark matter interactions and false positives. These false positives could be caused by other particles such as cosmic ray muons, high energy neutrons, and low energy neutrons interacting with the liquid argon detector. A veto detector was constructed and tested for use in the MiniCLEAN detector. Simulations were also run in order to characterize neutron signals in the liquid argon detector. [Preview Abstract] |
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EA.00006: Thickness Measurements and Isotopic Identification of Cd, Sn, and Te Targets Andrew Arend In preparation for measuring some of the reaction rates relevant to the p-process of stellar nucleosynthesis we characterized a set of 73 thin foil targets of Cd, Sn, or Te. The targets had Al or C backings and Al or Ta frames. Using Particle Induced X-ray Emission, we determined the elemental composition of each target by comparing the observed x-ray emission lines with that of the characteristic emissions of the relevant elements. We concluded that PIXE is not an accurate method of measuring foil thickness. We next used Rutherford Backscattering with 12C3+ beam to determine the isotopic composition and thicknesses of the targets. A Silicon detector was placed at 150 degrees with respect to the beam direction to detect the back-scattered 12C particles. A mixed alpha-source was used to ensure a good energy calibration. Analyzing the energy at the leading edge of the energy spectrum of the scattered particles allowed identification of the specific isotopes of in each sample. The width of the scattered 12C peak, indicating the maximum energy loss of 12C in a target, yielded the thickness of the target when compared to calculations. The thicknesses range from about 50 to 650 $\mu$g/cm$^2$. [Preview Abstract] |
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EA.00007: Truncation and Extrapolation of \textit{Ab initio} Calculations in a Finite Model Space M. Avetian, S.A. Coon, M.K.G. Kruse, U. van Kolck, P. Maris, J.P. Vary Estimating the errors due to the truncation to a model space is crucial for \textit{ab initio} calculations which require an extrapolation scheme to obtain a converged result in the full space. Of the calculations done in a harmonic oscillator (HO) basis, the model space is assumed to be characterized by $N_{max}$ which counts the maximum number of shells, above the minimum configuration, kept in the total energy. In the spirit of effective field theory (EFT) we have examined the dependence of the truncated results on two regulators of the model space. The HO ultraviolet (UV) regulator $\Lambda$ is associated with the maximum momentum included in the calculation. The infrared (IR) regulator $\lambda$ is associated with the minimum momentum variation allowed. Our investigations are made with different ``realistic'' $NN$ interactions smooth enough that these calculations, performed with a technology developed for the shell model, are variational in nature. Our energy spectra show a significant tendency towards simple scaling in these two regulators as the calculation approaches separately the IR and UV limits. We have established a novel extrapolation parameter composed of the two UV and IR regulators which appears universal (and $NN$ interaction and nucleus independent) and is useful even for modest model spaces. [Preview Abstract] |
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EA.00008: Characterization of $^{83}$Kr gas source for the Project 8 neutrino mass experiment Arman Ballado Measurement of the final state electron energy in tritium beta decay provides a model independent probe of the neutrino mass. However, reaching sufficient electron energy resolution may be be beyond the realm of current methods. Project 8 is a new experiment employing a novel, high-resolution non-destructive technique to measure the energy of single electrons via detection of the cyclotron radiation signal emitted by the electron in a magnetic field. The tritium endpoint energy of 18.6 keV in a 1T field corresponds to 26 GHz RF signal, and to test the sensitivity of this method, Project 8 will first attempt to demonstrate RF sensitivity to the 17.8 keV monoenergetic electrons as $^{83m}$Kr decays to the stable $^{83}$Kr. This project will explore the behavior of the krypton gas around liquid nitrogen temperatures to characterize the formation of a krypton monolayer on the surface of the vacuum chamber. The study hopes to find the optimal conditions to ensure minimal noise due to the electron-krypton scattering while still having enough concentration to produce a detectable signal. [Preview Abstract] |
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EA.00009: Calibrating the STAR Endcap Electromagnetic Calorimeter Using $\pi^{0}$'s Benjamin Barber Current calibrations of the STAR Endcap Electromagnetic Calorimeter (EEMC) have relied on the energy deposition of minimally-ionizing particles (MIPs). Alternative calibrations methods using the energy deposition of the di-photon pairs created by $\pi^{0}$ decays were explored, and used to verify the MIP-based method. Particle interactions with the EEMC result in energy clusters within the detector. Using standard two-body kinematics, the invariant mass spectrum of distinct energy cluster pairs is reconstructed from the 2009 data in the EEMC, resulting in a $\pi^{0}$ peak. Using this peak as the standard $\pi^{0}$ mass, parameters from the energy calibration for each EEMC detector element are varied to minimize the difference between the given and measured $\pi^{0}$ mass and the peak width. Current work has focused on the sensitivity of the resulting mass spectrum to the specific clustering algorithm used. Energy was clustered using K-means methods, fuzzy C-means methods, and a hybrid method of the two. Highlights and preliminary results will be presented. [Preview Abstract] |
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EA.00010: Pad Plane Design and Readout for SAMURAI TPC J. Barney, Z. Chajecki, C.F. Chan, J.W. Dunn, J. Estee, J. Gilbert, F. Lu, W.G. Lynch, R. Shane, M.B. Tsang, A.B. McIntosh, S.J. Yenello, M. Famiano, T. Isobe, H. Sakurai, A. Taketani, T. Murakami The SAMURAI TPC is being built at Michigan State University to be used in the SAMURAI spectrometer at RIKEN in Japan, as part of the Symmetry Energy project, which focuses on obtaining constraints on the symmetry energy at supra-saturation densities. The presentation will discuss the development of the TPC as well as design for readout plane design for the TPC. These involve enabling the use of existing and future front end electronics (FEE), making the most of limited space, designing a circuit board for the pad plane, and techniques to glue the pad plane. The pad plane has been designed to work with either STAR or AGET electronics. The pad plane is made of a circuit board designed to minimize crosstalk and capacitance. The board must be built in smaller pieces and tiled, using alignment pins and precision gluing. Prototypes for the pad plane to FEE connection, pad plane gluing and STAR card mounting will be presented. [Preview Abstract] |
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EA.00011: ABSTRACT WITHDRAWN |
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EA.00012: Observation of the J/Psi meson in Ultra Peripheral Collisions at STAR Gleb Batalkin Observation of the J/Psi meson in Ultra Peripheral Collisions at STAR Ultra Peripheral Collisions (UPC's) involve two colliding ions that do not physically overlap but interact electromagnetically. In UPC's, the exchange of virtual photons can lead to the photoproduction of vector mesons. The 2010 200 GeV Gold-Gold data from STAR contains the first evidence of photoproduction of J/Psi mesons in UPCs at STAR. The J/Psi meson is of particular interest because it probes the gluon distribution function at low-x. This poster will present the measurement of J/psi production in UPCs at STAR, including a Rho to J/Psi photoproduction cross section ratio. [Preview Abstract] |
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EA.00013: Systematic Search for Waiting Points in Nova Explosions Alexander Bennett, Michael Smith, Raphael Hix, Tomomi Sunayama To better understand the element synthesis and energy generation occurring in novae, we have executed a systematic search for waiting point nuclei. We used the waiting point finder tool within the Computational Infrastructure for Nuclear Astrophysics (CINA), an online suite of nuclear astrophysics codes that sets up, executes, and create visualizations of explosion simulations, to run a series of over five hundred post-processing nova simulations of different models, spatial zones, and time windows. We compiled a database of waiting points complete with a variety of search queries and a visualization tool to graphically aid in understanding nova explosions. We will report on our analysis of this waiting point dataset for trends across mass regions, zones, and time windows, and our searches for waiting points common to a variety of simulations. [Preview Abstract] |
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EA.00014: Construction of Specialty Guide Field Coils Using an Industrial Robotic Arm William Berry, Christopher Crawford, Mario Fugal, Elise Martin, Daniel Wagner, Robert Milburn Many contemporary nuclear physics experiments require precise control of the magnetic field within key regions of the experimental apparatus. The nEDM experiment, for instance, requires uniform guide fields (produced by guide field coils) to transport neutron spin polarization from the polarizer to the measurement cell. Guide field coils in general are subject to tight geometrical constraints, and must not produce any external fields which would affect the results of the experiment. In order to produce a satisfactory coil in light of these constraints, a systematic design technique is needed. We introduce the magnetic scalar potential technique, which calculates the exact coil windings required on a specified boundary to produce any desired field distribution inside that satisfies Maxwell's equations. Realizing the designs produced by this technique introduces an additional difficulty: winding many turns according to the exact calculated paths. This is addressed by ``printing'' our coils onto a copper-plated G10 form using a calibrated robot arm and spindle, resulting in a 3-d printed circuit board. To correct for deviations in the actual shape of the form, we use a laser displacement sensor to capture the actual geometry as input into the calculation of the windings. [Preview Abstract] |
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EA.00015: Position Sensitivity of the SuN (Summing NaI(Tl)) Scintillation Detector Ilya Beskin, Artemis Spyrou, Stephen Quinn, Jessica Peace, Anna Simon The astrophysical p-process is responsible for the synthesis of many proton rich nuclei. It involves photo disintegration reactions such as (gamma,alpha), (gamma,n) and (gamma,p) reactions. To try to understand the reaction flow and reproduce the p-nuclei abundances, we will try to study the inverse reactions, namely (p,gamma) and~(alpha,gamma). A beam of a heavy nuclei will be impinging on a~H or He rich target, and by using the 4$\pi$ $\gamma$-summing method, the cross section of (p,gamma) and (alpha,gamma) reactions will be measured. To do so, the Nuclear Astrophysics group at NSCL (National Superconducting Cyclotron Laboratory) is developing a scintillation detector. The SuN (Summing NaI) detector consists of eight semicircular segments, each with three PMTs (photomultiplier tubes) attached. This 4$\pi$ gamma-summing detector will allow us to measure the cross sections of important p-process reactions. The goal of my research was to find the correlation between the position of an event in the crystal and the signal recorded by each PMT. By correcting for this position dependence of the signals the energy resolution of the detector was improved. First results from this investigation will be presented. [Preview Abstract] |
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EA.00016: Dipole Transport in Multi-fragmentation Giacomo Bonasera The study of the Giant Dipole Resonance (GDR) in nuclei at low excitation energies (E*) gives access to information on the symmetry energy. Similarly the Isospin Transport Dipole (ITD) can be used to study the migration of protons and neutrons in a heavy ion collision at higher E*. Likewise to the Dipole mode definition used in GDR studies, we define a Dipole mode as:$D_z =\sum\limits_{i=\mbox{1}}^{A_{Qp}} {m_i} p_{zi}$ where$ m_i \;=\;\frac{\left( {N_i -Z_i } \right)}{A_i }$ of each fragment $\left( {N,Z} \right)_i$. The purpose of our analysis is to understand if the excess of neutrons leave the system with the gas, liquid or both. In order to achieve this goal we will study separately $p,n,^\mbox{3}He,t$ and heavier particles for the gas and the liquid components, respectively. In an equilibrated system the ITD is centered at zero, and its fluctuations are connected to the temperature. Collective effects, such as the Dipole dependence on the symmetry energy and the Coulomb field, may result in a non zero Dipole value. The ITD will be studied for different excitation energies to point out possible phase transitions, similar to those observed in the GDR of high E*. Moreover the study of different reaction systems will give hints on the role of neutrons, protons and heavier fragments in achieving equilibrium. [Preview Abstract] |
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EA.00017: Measurement of the Angular Distributions of Drell-Yan Dimuons Brandon Bowen The angular differential cross section for the Drell-Yan (DY) process can be parametrized by $\frac{d\sigma}{d\Omega}\propto 1+ \lambda \cos^2 \theta +\mu \sin 2\theta \cos\phi +\frac{\nu}{2}\sin^2\theta \cos 2\phi$, where $\lambda$, $\mu$, and $\nu$ are the angular distribution parameters vs $p_T$. $\theta$ and $\phi$ denote the polar and azimuthal angles, respectively for the positive lepton produced. The Lam-Tung relation, $1-\lambda = 2 \nu$, was validated by Fermilab E-866 for proton induced Drell-Yan scattering; However pion induced DY shows a much stronger cos2$\theta$ angular dependence and a violation of the Lam-Tung relation. In pion induced DY the antiquark is a valance quark, whereas in proton induced DY (in a forward acceptance spectrometer) it is a sea quark, so E-866 probed the antiquark sea of the nucleon. The SeaQuest experiment, also using proton induced DY, will improve on the measurement of the angular dependencies at a lower energy (120 GeV), taking advantage lower backgrounds and an increase in Drell-Yan cross section at lower energies. The Boer-Mulders correlates the quark correlates between the quark transverse spin and momentum. Improved data from SeaQuest will help determine the Boer-Mulders function. Funding for this work was provided in part by the U.S. DOE Office of Science. [Preview Abstract] |
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EA.00018: Germanium Crystal Growth for DUSEL Experiments Logan Brekke The Center for Ultra-low Background Experiments at DUSEL (CUBED) is a research center supported by both DOE EPSCoR and the state of South Dakota to grow high-purity germanium crystals for Deep Underground Science and Engineering Laboratory (DUSEL) projects at the Homestake mine in Lead, SD. My specific project within the CUBED program was Germanium Crystal Growth. I assisted in growing Ge crystals using the Czochralski method, along with producing and examining Ge wafers fashioned from the crystals we grew. Our main goal was to perfect the growth process, aiming to eventually grow Ge crystals that meet the strict high-purity and low-dislocation requirements of detector-grade crystals. Throughout the summer, we made significant progress and improvements to our growth equipment and technique. The research and process development performed within the CUBED program are preliminary activities in a much larger project. The ultimate objective is to move the crystal growth and other activities underground to DUSEL, thereby making it the only site in the world where high-purity Ge crystals are grown in a deep underground environment. Through our research and development we are contributing to the efforts of the DUSEL project by assembling and improving both knowledge and strategy of the crystal growth process and equipment. This groundwork will allow for a ``running start'' once the activities are moved to the underground site. [Preview Abstract] |
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EA.00019: Dark Matter Detection with DM-Ice Benjamin Broerman There is strong evidence for the existence of dark matter, theoretically favored to be a weakly interacting and gravitationally influential form of non-baryonic matter. The $\Lambda$CDM model delineates 23\% of the mass-energy of the Universe to be dark matter, 73\% dark energy, and the remaining 4\% baryonic matter. However, conclusive evidence as to the direct detection of dark matter has yet to be produced. In December 2010, a new project, named DM-Ice, deployed two prototype NaI detectors in the South Pole ice, testing the feasibility for a future, larger-scale direct detection experiment. The goal is to search for the annual modulation signal expected from interactions between the target nuclei and the weakly interacting massive particle (WIMP), a candidate dark matter particle. I will report on my contributions to data readout and analysis, as well as preparations for the future experiment. [Preview Abstract] |
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EA.00020: Development of the Silicon Array at Notre Dame (SAND) for the Study of the 12C + 12C Reaction at Sub-Coulomb Energies Craig Cahillane The 12C + 12C fusion reaction is an important process in stellar evolution and nucleosynthesis. The energy region of interest lies between 1 and 3 MeV, but studying the reaction at these energies is difficult because of the reaction's rapidly decaying cross-section a sub-Coulomb energies. Both detector efficiency and beam intensity limit such measurements. As a test run for the future Silicon Array at Notre Dame (SAND), two YY1 Trapezoid Silicon Detectors were used to detect the proton decay of the carbon fusion reaction. The two detectors covered a solid angle of 0.34 steradians. In the construction of SAND, more large surface area silicon detectors will be used to dramatically increase detection efficiency by covering a much larger solid angle. Combined with the new high-intensity 5 MV accelerator also under construction at Notre Dame, SAND could reduce the error on low energy cross sections in the astrophysical region and possibly detect hypothesized resonances at lower energies. [Preview Abstract] |
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EA.00021: Gas Electron Multiplier Tracking Telescopes for OLYMPUS Miles Campbell, Joshua McMahon The OLYMPUS collaboration is conducting an experiment to measure two-photon contributions to elastic electron scattering. The experiment is taking place at the DORIS storage ring at DESY, Hamburg, Germany using the upgraded BLAST detector from the MIT-Bates Linear Accelerator Center. Gas Electron Multiplier (GEM) telescopes are used to detect scattered leptons at a forward angle to monitor the luminosity. The GEM detectors have been commissioned at the test facility at DESY and were installed along with the main detector in the DORIS storage ring. With the testbeam the performance characteristics such as gain, efficiency, multiplicity, and resolution of the GEMs were studied. [Preview Abstract] |
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EA.00022: Gain Calibrations for the BUNI Large-Volume NaI(Tl) Detector at MAX-lab Olivia Campbell One of the most critical questions in nuclear physics today is how to describe the properties of the nucleon in terms of the framework provided by Quantum Chromodynamics. A number of different approaches to solving the QCD calculations at low energies exist. Comparing the results from high quality measurements with the predictions from various quark-based theories provides a way to test the theories. Pion photoproduction near threshold is one fundamental nuclear reaction where both theory and experiment can provide accurate answers. A measurement of $\gamma n \rightarrow p \pi^-$ is currently being performed using the photon tagging facility located at MAX-lab in Lund, Sweden. Since a LD$_2$ target was used, the $\pi^-$ cannot escape to be detected directly but are instead captured in the target and produce a nominal 128 MeV gamma-ray. These high-energy gamma-rays were detected in three large-volume NaI(Tl) detectors. The detectors have a core surrounded by a segmented annulus. During the data acquisition period, daily calibration runs were made using a Th-C $\gamma$-ray source to measure the gain of the annulus segments. These calibrations ensured that changes in the detector gains were accurately monitored and corrected for during the analysis of the data. [Preview Abstract] |
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EA.00023: Rate Capability in Bakelite Based Resistive Plate Chambers Max Candocia Bakelite-based resistive plate chambers (RPCs) are particle detectors commonly used in muon trigger systems for high-energy physics experiments. Bakelite RPCs combine fast response, sufficient position resolution and low cost, and they can be operated at~instantaneous~background rates up to about 1.5 kHz/cm$^2$. Current and future collider experiments will demand operation of trigger RPCs under background rates higher than what is currently achieved. The rate capability is related to the bulk and surface~conductivities~of the Bakelite material used for the plates~bordering~the active gas volume in the RPCs. The inner surface of present Bakelite RPCs used at the LHC and RHIC is coated with linseed oil, lowering the surface resistivity of the raw Bakelite. Methods of increasing the surface conductivity of Bakelite sheets via dispersion of carbon blacks in linseed oil are being developed. Performance tests of~prototype RPCs are carried out in a test stand that utilizes cosmic ray muons and radioactive 55Fe sources. In this presentation~different dispersion methods and the rate capability of the resulting prototype RPCs will be compared. [Preview Abstract] |
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EA.00024: ABSTRACT WITHDRAWN |
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EA.00025: First Measurement of Statistical Gamma-ray Transitions in $^{88}$Sr at TUNL via Inelastic Neutron Scattering S. Carter, G. Rusev, C. Arnould, W. Tornow, M. Gooden, J.H. Kelley, S.L. Hammond, L. Stevens Predictions of the intensity distribution of $\gamma$ rays emitted by product nuclei of a certain nuclear reaction are of interest for nuclear astrophysics to estimate the photon flux during a supernova as well as for applied physics for calculating radiation shielding, for instance. Furthermore, by knowing the average $\gamma$-ray spectrum for a given isotope we can predict whether the nucleus will transmute if it is exposed to a strong $\gamma$ flux as the ``hot supernova-explosion scenario'' suggests. We report results for the distribution of $\gamma$ rays following the $^{88}$Sr(n,n'$\gamma$) reaction. This experiment, carried out for the first time at TUNL's FN 10 tandem, aims at measurement of the statistical $\gamma$ rays and is complementary to our previous experiments on $^{87}$Sr(n,$\gamma$) at LANSCE and $^{88}$Sr$(\gamma,\gamma')$ at the High Intensity $\gamma$-Ray Source Facility. [Preview Abstract] |
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EA.00026: NIFFTE Time Projection Chamber for Fission Cross Section Measurements Ryan Castillo In order to design safer and more efficient Generation IV nuclear reactors, more accurate knowledge of fission cross sections is needed. The goal of the Time Projection Chamber (TPC) used by the Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration is to measure the cross sections of several fissile materials to within 1{\%} uncertainty. The ability of the TPC to produce 3D ``pictures'' of charged particle trajectories will eliminate unwanted alpha particles in the data. Another important source of error is the normalization of data the U-235 standard. NIFFTE will use the H(n,n)H reaction instead, which is known to better than 0.2{\%}. The run control and monitoring system will eventually allow for nearly complete automation and off-site monitoring of the experiment. This presentation will cover the need for precision measurements and an overview of the experiment. [Preview Abstract] |
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EA.00027: Prototyping A Gas Electron Multiplier For Use At TJNAF Chris Colvin I am currently working on, and studying, prototype GEM detectors at the Thomas Jefferson National Accelerator Facility (TJNAF). The goal of this project is to be able to implement a large scale version of this technology into the halls of the accelerator. A GEM (Gas Electron Multiplier) detector is relatively cutting edge technology, first used at CERN in 1997. The models we use receive a constant flow of mixed gas ($75\%$Argon, $25\%$ Carbon Dioxide). The inner workings of the GEMs contain 3 layers of Kapton foil with microscopic engineered holes. Electrons are multiplied inside the holes as they drift along lines created by an external electric field. This charge is collected on two planes of readout strips which are perpendicular to each other, allowing the measurement of the x and y directions. The z- coordinate comes from stacking 3 of these chambers on top of each other. This data is then sent through a costumized data acquisition system for analysis. [Preview Abstract] |
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EA.00028: Complementary Neutron Efficiency Measurements using VANDLE P. Copp, W.A. Peters, R. Grzywacz, M. Madurga, S. Paulauskas, J.A. Cizewski, M.E. Howard, P.D. O'Malley, B. Manning, E. Merino, T.N. Massey, C. Brune, F. Sarazin, S. Ilyuskin, D. Walter, J. Blackmon, D.W. Bardayan, I. Spassova, C. Matei The Versatile Array of Neutron Detectors at Low Energy at the Holifield Radioactive Ion Beam Facility at ORNL is nearly complete for use with a variety of neutron-detection senarios, including (d,n) reactions in inverse knimatics and beta-delayed neutron spectroscopy. The array is comprised of detector modules with two different sizes of scintillating plastic bars. The smaller modules are 60 cm long while the larger ones are 200 cm long. The efficiency of these modules has been measured by comparing to a calibrated $^{27}$Al(d,n) reaction performed at Ohio University, and by comparing to a measured $^{252}$Cf decay spectrum. Both results will be presented along with the characterization of the light response of elastically scattered low energy carbon recoils below 30 keVee. [Preview Abstract] |
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EA.00029: A Calibration Technique for the ALICE Electromagnetic Calorimeter at the Large Hadron Collider Karen Cossyleon, Chaan Thomas, Edmundo Garcia-Solis, Mateusz Ploskon, Peter Jacobs The Large Hadron Collider at CERN is the world's largest and highest energy, particle and heavy ion collider. The LHC explores the frontiers of particle physics using high energy proton + proton collisions and the properties of the Quark-Gluon Plasma through the collision of heavy nuclei. ALICE is one of the four LHC experiments, specialized for the study of heavy ion collisions. This study presents our work on a detector of ALICE, the Electromagnetic Calorimeter. We are analyzing the proton-proton collision data recorded at 2.76 TeV. The ALICE TPC is used to isolate the tracks of e$^{+ }$e$^{-}$ pairs that originate from the decay of J/$\Psi $ particle and that fall within the EMCal's acceptance. The TPC measures the momentum of these electron tracks, which is compared to the energy deposited by them in the EMCal. We therefore use the precise measurement of TPC momentum as the reference to calibrate the EMCal energy measurement. In this presentation we will show the steps taken to analyze the data, how we performed the matching of electron tracks from the J/$\Psi $ decay with the energy deposited in the EMCal and some preliminary results. [Preview Abstract] |
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EA.00030: Measurement of the Background Gamma Spectrum at the SNS FP12 K. Craycraft The NPDGamma experiment is running at the Fundamental Neutron Physics Beamline (FP13) of the Spallation Neutron Source (SNS). It will measure the parity violating weak contribution to the long range part of the hadronic interaction in the reaction n + p $\to$ d + gamma. We have measured the background gamma-ray spectrum in the FP13 experimental area using a high purity germanium detector. Various sources of background are discussed, including the supermirror polarizer, and materials in the target and detector array, and their projected effect on the NPDGamma experiment. [Preview Abstract] |
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EA.00031: Exploring the EMC Effect and Anti-Shadowing at Fermilab E906/SeaQuest Mandi Crowder Fermilab E906/SeaQuest will use Fermilab's 120 GeV Main Injector on the nuclear targets Ca, W, and C to investigate how sea quark distributions differ in nuclear matter. The European Muon Collaboration (EMC) discovered that the quark structure of a nucleon has a different momentum distribution than that of nuclei. SeaQuest is a fixed target experiment designed to extract the sea anti-quark structure of the proton by measuring the Drell-Yan cross-section ratio for proton-proton and proton-deuterium collisions. The data gathered will also aid in understanding parton energy loss in cold nuclear matter, which is a prerequisite to understanding energy loss in hot nuclear matter at RHIC and the LHC. Anti-shadowing causes higher energy loss but was not observed in Fermilab E772 Drell-Yan data. SeaQuest will study these nuclear effects for the anti-quark distributions over the anti-shadowing (0.1 $<$ Bjorken x $<$ 0.2) and EMC (0.2 $<$ x $<$ 0.5) regions to a much higher precision than E772. [Preview Abstract] |
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EA.00032: Examination of the validity of statistical models for the $^{12}$C + $^{12}$C fusion reaction at sub-barrier energies Erin Dahlstrom Previous experimental studies of $^{12}$C + $^{12}$C fusion at sub-barrier energies using gamma spectroscopy have been limited by the use of a single detector. Use of the Gammasphere at the Argonne National Laboratory, however, allows for an array of germanium detectors to pick up the characteristic gamma rays, greatly increasing the information received. These decay products do not give us the total cross section for the fusion reaction though; we rely on statistical models that relate them to how the excited states are originally populated and decay. Using a combination of gamma spectroscopy based on data from the Gammasphere and proton spectroscopy from a recent $^{12}$C + $^{12}$C fusion experiment at Notre Dame, we tested these statistical models. The initial population of excited states for $^{23}$Na predicted by Empire, a standard statistical model for the decay of different $^{24}$Mg spins, was compared with the population determined from the gamma and proton spectroscopy. This comparison will potentially help us more accurately predict the spin population of $^{24}$Mg, further constraining the fusion reaction theory. [Preview Abstract] |
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EA.00033: Development of CdWO$_{4}$ Crystal Detectors Alyssa Day CdWO$_{4}$ scintillators have been proposed for detecting geo-neutrinos, neutrinoless double-beta decay, and dark matter. Initial research involved an energy resolution comparison of three different sized gamma ray detecting CdWO$_{4}$ crystals. The three crystals had diameters of 16mm and thicknesses of 5mm, 9mm, and 19mm, respectively. When using the 19mm CdWO$_{4}$ crystal, the energy resolution of a $^{137}$Cs source resulted in 11.4{\%} at 662 keV. A $^{60}$Co source used with the same crystal resulted in 6.5{\%} at 1173.2 keV and 8.6{\%} at 1332.5 keV. As the sizes of the crystal decreased, a slight deterioration in energy resolution occurred with more Compton scattering in the energy spectrum. The CdWO$_{4}$ crystal was beneficial when measuring gamma-ray energy close to 511 keV, which is the primary signature for geo-neutrino detection with $^{106}$Cd. By initially using a number of smaller crystals, small scale experiments can be run to develop and understand the calibration of these crystals. Current experiments involve using a 2 inch CdWO$_{4}$ crystal. It is predicted that with the use of this larger crystal, energy resolution and detection with be improve. The results of this experiment will be presented. [Preview Abstract] |
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EA.00034: Learning about scalars in the dark sector from generic fifth force searches Ross DeVol, Gintaras Duda To explain the PAMELA/FERMI positron excess through dark matter annihilations, leptophilic dark matter, dark matter that preferentially decays into leptons, is needed. Models such as exciting dark matter (XDM) provide a new annihilation channel for dark matter, \textit{$\chi \chi \to $??}, where $?$ is a new scalar particle. The decay of this scalar into electron-positron or muon-antimuon pairs can explain the PAMELA excess. Since scalar fields generically lead to fifth-force type interactions, this scalar particle and its interactions are constrained by generic fifth force searches. This work will present constraints on the mass of the new scalar particle in the dark sector from fifth force searches. [Preview Abstract] |
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EA.00035: Fabrication of a Low Radioactive Background Temperature Sensor on a Parylene Substrate Ankur Dhar, James Loach, Alan Poon Searches for rare nuclear processes are at the center of many research programs in nuclear and particle physics and as these experiments increase in sensitivity there is an growing need for materials with higher radiochemical purity. A particular need is for low-background electronic circuitry and sensors, an example of which is a temperature sensor for use in neutrinoless double beta decay and dark matter experiments. In this work a thin-film temperature sensor is fabricated from radio-pure materials to provide a clean alternative to conventional platinum or silicon diode sensors. Parylene is used as a substrate for sputtered gold-titanium traces shaped using photolithography and bonded to parylene-coated copper signal wires; the whole sensor is the then sealed with a second layer of parylene. Parylene is a promising substrate material for low-background electronics and this work represents a proof-of principle and a first step on the road to more complex sensor electronics. [Preview Abstract] |
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EA.00036: A Microscopic Description of the Elusive Hoyle State Alison Dreyfuss, Kristina Launey, Cairo Bahri, Tomas Dytrych, Jerry Draayer Using the symplectic Sp(3,\textbf{R}) symmetry inherent to nuclear dynamics together with a novel many-nucleon interaction, we are able to reproduce low-lying spectral features of $^{12}$C, including the Hoyle state energy, and to gain a further understanding of the underlying physics. We employ a no-core symplectic model for symmetry-preserving interactions--with Sp(3,\textbf{R}) the underpinning symmetry --that offers a microscopic description of nuclei in terms of mixed shape deformations and allows for the inclusion of higher-lying configurations currently inaccessible to ab initio shell models. Our interaction is effectively realized by an exponential dependence on the quadrupole-quadrupole two-body interaction. We were able to reproduce the energies of the ground state rotational band, the Hoyle state, and the next excited $0^+$ state, along with the $B(E2: 2_1^+ \rightarrow 0^+_{\rm g.st.})$ transition strength for $^{12}$C. The success of this work indicates the importance of alpha-cluster structures in the $^{12}$C nucleus and the inclusion of hierarchical many-body interactions. [Preview Abstract] |
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EA.00037: The SAMURAI Time Projection Chamber Steven Dye The SAMURAI Time Projection Chamber (TPC) will be used to study particle collisions by colliding a beam of particles with a stationary gas which will be contained in a field cage inside the TPC. When the beam collides with the gas, charged particles are accelerated into the pad plane by an electric field. The paths of these particles will be curved by a magnetic field created by the SAMURAI magnet at the RIKEN facility in Japan. The charged particles will then collide with the pad plane which will be located on the bottom of the TPC. The pad plane will take these collisions and create electrical signals and send them to supporting electronics where the data can be interpreted. The TPC will be used to help determine the Equation of State for asymmetric nuclear matter. Measurements of neutron, proton, $^{3}$H and $^{3}$He flow will be taken with the NEBULA array which consists of nebula scintillators. The poster will contain information on the laser calibration system and the electronics that will be used for the TPC. The electronics used are the same electronics used in the STAR TPC experiment. [Preview Abstract] |
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EA.00038: Calibration of the NEXT-1 Time Projection Chamber for Neutrinoless Double Beta Decay Searches Maxim Egorov We propose a high-pressure Xe-136 gas time projection chamber (TPC) for searches of neutrinoless double beta decay. Currently, the prototype NEXT-1 TPC has been constructed at Lawrence Berkeley National Laboratory that uses 1 kilogram of Xe-136. We used a radioactive Am-241, 59.4 keV gamma-ray source for calibration of the TPC, and a GEANT4 Monte Carlo simulation for determining the accuracy of the position and energy reconstructions. The detection mechanism in the TPC relies on the process of electroluminescent amplification that yields a large photon count for signal events. The optical settings were thus optimized to yield accurate position and energy reconstructions to 50{\%} total, fully diffuse, reflectivity. We developed a maximum likelihood estimation method for position reconstruction that demonstrates 90.2{\%} accuracy for simulated events. At full calibration energy, the energy resolution was found to be $\sim $4.6{\%} FWHM, with simulation showing similar results, but still not matching the expected resolution of $\sim $2.6{\%} FWHM. Accurate position reconstruction allows for an accurate radial correction on the energy, which could lead to an improved energy resolution. [Preview Abstract] |
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EA.00039: Modeling neutron events in MoNA-LISA using MCNPX Margaret Kendra Elliston, Alexander Peters, Kristen Stryker, Sharon Stephenson The MoNA-LISA collaboration uses time-of-flight techniques and charged particle detectors to determine the structure of exotic nuclei such as $^{24}O$ and $^{12}Be$. To determine the decay energy in particular, a neutron that hits the Modular Neutron Array and the Large multi-Institutional Scintillator Array has its energy, position and angle of incidence recorded if and only if the charged particle detector system detects an appropriate charged-particle fragment. However, the analysis uses only the first neutron to hit the detector array even in the case of 2n events, since the data acquisition system cannot distinguish between simultaneous but random 2n events and events due to 2n reactions. We are using MCNPX to model the reaction channels possible in the MoNA-LISA detector system in an effort to better improve the resolution on decay energy spectra for events with multiple neutrons. [Preview Abstract] |
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EA.00040: Bottomonium in the QGP: Production at RHIC and LHC Andrew Emerick, Ralf Rapp Quantum chromodynamics (QCD) governs the strong interaction, describing the confinement and asymptotic freedom of quarks and gluons. Utilizing ultrareletavistic heavy ion collisions, matter past the critical temperature (T$_{C }\cong $180 MeV), the region of the quark-gluon plasma (QGP), can be produced. Lattice QCD computations indicate that resonances of heavy quarkonia survive well past the critical temperature: up to 3-4T$_{C }$for bottomonia ($\Upsilon )$. These bound states, such as J/$\psi $ and $\Upsilon $, are used as essential probes into the phenomenology of the QGP. Euclidean correlator ratios are calculated utilizing in-medium spectral functions for two heavy quarkonia dissociation mechanisms: gluo dissociation (g+$\Upsilon \quad \to $ b+b\={ }) and quasi-free dissociation (g,q,q\={ } + $\Upsilon \quad \to $ g,q,q\={ } + b + b\={ }), corresponding to the strong and weak binding scenarios respectively. These calculations motivate the necessity to reconsider gluo dissociation as the dominant process for $\Upsilon $ in the QGP. Utilizing a kinetic-theory rate-equation approach, the production, suppression, and regeneration of $\Upsilon $'s in AuAu (PbPb) collisions at RHIC and LHC with $\surd $s$_{NN}$ = 200 GeV (2.76 TeV) is calculated and compared to recent STAR (CMS) preliminary data. Treatment is also given to cold nuclear matter effects, simulated by nuclear absorption. [Preview Abstract] |
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EA.00041: Detection Efficiency of the Clover Array for Recoil Decay Spectroscopy John Engel, Mahammad Al-Shudifat, S.V. Paulauskas, Miguel Madurga, Robert Grzywacz The Clover Array for Recoil Decay Spectroscopy (CARDS) has been implemented in the newly commissioned facility Low-energy Radioactive Ion Beam Spectroscopy Station at Oak Ridge National Laboratory. Challenging experiments with very neutron rich isotopes near doubly magic $^{78}$Ni has been performed. Quantitative analysis of the new data required a thorough measurement of the detection efficiency of the CARDS array using variety of the standard calibration sources. Of particular importance is observed high detection efficiency for gamma rays with energies in the range of 50-200 keV which has been achieved due to implementation of digital electronics. Examples of data from on-line experiments will be presented. [Preview Abstract] |
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EA.00042: Measurement of the Total Cross Section for $\gamma n \rightarrow p \pi^-$ Near Threshold at MAX-lab Khayla England In nuclear science, researchers strive to describe the properties of the nucleons using the framework provided by QCD. A number of theoretical approaches to solving the QDC equations for nuclear processes exist. The predictions of these theories can be compared with the results from accurate experimental measurements for those nuclear reactions where both theory and experiment can provide accurate answers. One such reaction is pion photoproduction near threshold. A measurement of the total cross-section very close to threshold for the $\gamma + n \rightarrow p + \pi^- $ reaction is currently being performed using the Tagged Photon Facility at MAX-lab in Lund, Sweden. A LD$_2$ target was used to provide the neutron target. Due to the target thickness, the $\pi^-$ were not detected directly but instead were captured on another nucleus in the target. This capture resulted in a nominal 128 MeV $\gamma$-ray approximately 25\% of the time. This gamma-ray easily exited the target and was detected using three large NaI(Tl) detectors: CATS, BUNI, and DIANA. An overview of the measurement and preliminary results from the June 2011 run period will be presented. [Preview Abstract] |
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EA.00043: Development of a Polarized He3 Ion Source for RHIC Charles Epstein, J. Alessi, E. Beebe, W. Heil, S. Karpuk, R. Milner, E. Otten, A. Pikin, A. Zelenski A polarized $^3$He beam in RHIC would enable new, unique, high-energy QCD studies of neutron structure with existing polarized proton beams, as well as important tests of the standard model in a future electron-ion collider (eRHIC). A new polarized $^3$He ion source using the Electron Beam Ionization Source (EBIS) at BNL is under development. $^3$He atoms are first polarized using metastability exchange optical pumping (MEOP) and then transferred to EBIS. Fully stripped $^3$He$^{++}$ ions would be extracted from EBIS and their polarization measured at low energies before acceleration in RHIC. [Preview Abstract] |
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EA.00044: Improving Thick Germanium Detectors: Cryogenic Dark Matter Search Paulette Epstein, Rupak Mahapatra Texas A{\&}M University is working on improving the current production rate, quality, and reproducibility of fabricated detectors, specifically for the Cryogenic Dark Matter Search (CDMS) to detect particles called WIMPs (Weakly Interacting Massive Particles). An automated sputtering system is used to deposit amorphous silicon and high quality tungsten and aluminum thin-films on 3 inch by 1 inch germanium substrates to demonstrate repeatable depositions with desired properties, such as, accurate thickness, desirable critical temperature, and good sensitivity at low energy. These techniques can then be used in the future to improve detectors, not only for the search for Dark Matter, but for other areas of research in nuclear and particle physics. [Preview Abstract] |
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EA.00045: (d,n) Proton Transfer Reactions Relevant to Nuclear Astrophysics: The case of $^{17}$O(d,n)$^{18}$F in Inverse Kinematics Ediz Ersoy The (p,y) process plays an important role in stellar nucleosynthesis and the long term evolution of stars. The (p,y) direct capture process is difficult to observe experimentally due to the low energies and small reaction cross-sections involved, however by comparison, the (d,n)$^{ }$proton transfer process has higher reaction cross-sections in addition to providing insight into the (p,y) process through observations involving neutron kinematics. The particular (d,n) reaction investigated using inverse kinematics was the $^{17}$O(d,n)$^{18}$F reaction. Neutron detection for the $^{17}$O(d,n)$^{18}$F reaction is to be done utilizing the LENDA (Low Energy Neutron Detector Array) detectors. Several calculations were conducted to observe specific excitation levels of astrophysical interest between 5 and 7MeV. These calculations included correlations of neutron and $^{18}$F kinetic energies with their center of mass and scattering angles at different excitation energies. The calculations further included detector placement and coverage for the observation of neutrons and $^{18}$F isotopes. The time-of-flight and angular resolutions of the LENDA detectors were also studied in the calculations. [Preview Abstract] |
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EA.00046: Non-Uniform Electromagnetic Fields in the SAMURAI TPC J. Estee, J. Barney, Z. Chajecki, C.F. Chan, J.W. Dunn, J. Gilbert, F. Lu, W.G. Lynch, R. Shane, M.B. Tsang, A.B. McIntosh, S.J. Yennello, M. Famiano, T. Isobe, H. Sakurai, A. Taketani, T. Murakami A Time Projection Chamber (TPC) is being developed for the SAMURAI dipole magnet at RIKEN. The main scientific objective for the TPC is to provide constraints on the nuclear symmetry at supra-saturation density. The poster presentation will discuss the design of the TPC field cage and the external electrodes that shape the high electric fields near the cathode. Garfield calculations of the electric field as well as TOSCA calculations of the magnetic field of the SAMURAI dipole will be shown and the impact of the non-uniformity of both fields on electron transport will be discussed. These non-uniformities can introduce components into the electron drift velocity in directions other than the expected vertical direction. This poster presentation will discuss the initial design of a laser calibration system, which will be used to calibrate away the influence of these non-uniformities in the electric and magnetic fields. [Preview Abstract] |
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EA.00047: Search for Local Parity Violation in Au+Au collisions at 62.4 GeV at STAR Midhat Farooq Parity-odd domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in non-central relativistic heavy ion collisions [1]. A signal consistent with several of the theoretical expectations has been reported by STAR [2]. The measurement is based on a three particle azimuthal correlator, a $P-$ even observable, but sensitive to the charge separation effect. However, the limited statistics of the published results for 62.4 GeV prevented us from a detailed comparison of data between 200 GeV and 62.4 GeV, especially for the more peripheral collisions. In RHIC run2010, high statistics of Au+Au collisions have been taken by STAR, and that enables us to carry out the beam-energy scan of the signal and to revisit 62.4 GeV with much better precision. In this work, we present the measurement of three particle correlator as a function of centrality for Au+Au collisions at 62.4 GeV, and we discuss the energy dependence of the results from 62.4 GeV to 200 GeV. \\[4pt] [1] D. Kharzeev, Phys. Lett. B 633, 260 (2006). \\[0pt] [2] B. I. Abelev et al., Phys. Rev. C81 (2010) 54908. [Preview Abstract] |
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EA.00048: Development of Single-Sided Enriched Oxygen-16 and 18 Targets for Exotic Beam Studies Michael Febbraro, Frederick Becchetti, Mitaire Ojaruega, Ramon Torres-Isea A technique for the preparation of large reasonably uniform single-sided enriched oxygen targets for radioactive nuclear beam (RNB) experiments using anodization of thin tantalum foils in enriched water is currently being developed. Targets with an active area of 25 mm diameter (and larger) have been prepared using a constant-current source in H$_{2}^{16}$O with an additional electrolyte. Currently, work is being done on developing a pulsed-current method for anodization. It is proposed that the pulsed current (a technique used in commercial applications) will increase surface uniformity by replenishing ions lost locally from the redox reaction, as well as reduce pin-holes in the Ta$_{2}$O$_{5}$ layer by periodic ``flushing'' of hydrogen gas produced at the surface. The highly exothermic nature of the $^{16}$O($^{7}$Be, $^{3}$He) reaction planned, allows for single-sided targets on relativity thin supporting foil to be utilized since, the energetic $^{3}$He ions produced will lose minimal energy in the support foil. Testing of the targets will be conducted at the UM-UND \textit{TwinSol} RNB facility as a joint project between the University of Michigan and the University of Notre Dame funded by grants from the NSF. [Preview Abstract] |
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EA.00049: A Monte Carlo Simulation for Understanding Energy Measurements of Beta Particles Detected by the UCNb Experiment Chi Feng It is theorized that contributions to the Fierz interference term from scalar interaction beyond the Standard Model could be detectable in the spectrum of neutron beta-decay. The UCNb experiment run at the Los Alamos Neutron Science Center aims to accurately measure the neutron beta-decay energy spectrum to detect a nonzero interference term. The instrument consists of a cubic ``integrating sphere'' calorimeter attached with up to 4 photomultiplier tubes. The inside of the calorimeter is coated with white paint and a thin UV scintillating layer made of deuterated polystyrene to contain the ultracold neutrons. A Monte Carlo simulation using the Geant4 toolkit is developed in order to provide an accurate method of energy reconstruction. Offline calibration with the Kellogg Radiation Laboratory 140 keV electron gun and conversion electron sources will be used to validate the Monte Carlo simulation to give confidence in the energy reconstruction methods and to better understand systematics in the experiment data. [Preview Abstract] |
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EA.00050: Analysis of the Farmville Meteorite Megan Ferm Meteoroids are objects that are constantly bombarded by cosmic rays in outer space. Through spallation reactions between cosmic rays and meteoroid matter, radioactive nuclides, such as $^{26}$Al, are produced. $^{26}$Al is a positron emitter, meaning that the positron annihilates within a cubic millimeter of the sample. This results in the release of two 511 keV photons, in addition to an 1809 keV gamma ray from the decay to the $^{26}$Mg ground state. This study focuses on the detection of $^{26}$Al in the Farmville meteorite, which fell in North Carolina in 1934. The meteorite has been centered in our sensitive apparatus, and the conditions for detection require a triple gamma coincidence which greatly reduced background. With the radioisotopes measured within the sample, Monte Carlo transport simulations (using the package Geant4) will be performed to determine the amount of $^{26}$Al in the meteorite. With this information, it may be possible to determine the time the meteorite entered Earth's atmosphere (which should be consistent with the reported find time), the time period that the meteoroid was exposed to the cosmic rays, the pre-atmospheric size of the meteoroid and the intensity of cosmic rays in the inner solar system. [Preview Abstract] |
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EA.00051: Optimization of a Scintillator for the Measurement of Positrons from Trapped, Polarized $^{37}$K Erin France, Dan Melconian Precision beta decay experiments can be used to test the Standard Model via their value of correlation parameters. The TRINAT collaboration is performing such an experiment using a source of polarized $^{37}$K from a magneto optical trap. The momentum of an emitted positron will be detected using a Silicon strip detector backed by a plastic scintillator. The goal of my research was to optimize the readout of the scintillator by testing different experimental setups. The front face and sides of the scintillator and light guide were wrapped with various reflective materials to find which maximized the light output. We found that one layer of Teflon tape on the front face with a loose wrapping of 3M-ESR (Enhanced Spectral Reflector) on the sides was optimal. We then tested the position dependence of this detector by moving a collimated source of betas across the front face, showing only a (5.9 $\pm$ 0.5)\% reduction in light collection at the edge compared to the center. The product of this work will be used in the upcoming TRINAT experiment measuring the beta asymmetry of $^{37}$K. [Preview Abstract] |
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EA.00052: Updating the Qweak Database: Maintenance and Accessibility Matthew Gammill, Damon T. Spayde The Qweak experiment at Thomas Jefferson National Accelerator Facility is being conducted by a collaboration representing over 25 universities and research institutions, and is an attempt to measure with very low total uncertainty, 4\%, the weak nuclear charge of a proton through parity-violating elastic electron-proton scattering. The weak charge can be used to calculate the running Weinberg mixing angle. The Standard Model makes a confident prediction for the mixing angle at low energies, so divergence could point to physics beyond the Standard Model, while agreement will constrain new and existing models. The expected asymmetries are on the order of a few hundred parts per billion, so an exceptional quantity of data (2200 beam-hours) must be gathered. Storing and organizing this data presents a considerable challenge, which the Qweak database aims to satisfy. Tools to improve accessibility for researchers, efforts to improve efficiency, statistical and data quality checks, and ongoing expansion of the database will be discussed. [Preview Abstract] |
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EA.00053: Testing a New System for Charged-Particle Nuclear Reactions Hannah Gardiner, Jeffrey Blackmon, Laura Linhardt, Kevin Macon, Milan Matos, Charlie Rasco, Lagy Baby, Yevegn Koshchiy, Grigory Rogachev, D. Santiago-Gonzalez, Ingo Wiedenhover, Dan Bardayan The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array that is targeted towards reaction studies with radioactive ion beams at FSU and the NSCL primarily to help improve understanding of the nuclear reactions important in stellar explosions. A gas-filled ionization chamber with 10 alternating anode/cathode planes was developed and tested for use with ANASEN to identify the atomic number of recoiling heavy ions by their relative energy loss in passing through the gas. This ionization chamber, in conjunction with high-purity silicon detectors and ASIC electronics, was tested using the 17O(p,alpha)14N reaction at FSU. We report on the performance (efficiency and energy resolution) from this test experiment and on plans for improving the ionization counter detector design. [Preview Abstract] |
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EA.00054: Simulating Radioactive Decays in Next Generation Geoneutrino Detectors Megan Geen From analyzing geological samples, the radioactive decays from isotopes $^{238}$U, $^{232}$Th, and $^{40}$K are believed to produce most of the Earth's internal energy. To confirm how much energy these three isotopes are producing, scientists can measure the number of anti-neutrinos (geoneutrinos) which are a product of these decays. While other particles produced by these decays are stopped within the Earth through various interactions and never make it to our detectors, geoneutrinos do not interact and get stopped as frequently making them a good indicator of how many decays actually occur below the Earth's crust. Unlike old geoneutrino detectors, we are developing a new detector that takes advantage of total internal reflection to reduce the number of photomultiplier tubes needed and improve our ability to identify the particle type that reacted within the detector. I will be presenting how we take advantage of total internal reflection in the new detector's design and how we identify when a geoneutrino has reacted within the detector based on Monte Carlo simulations. [Preview Abstract] |
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EA.00055: Conceptual Design Calculations for the Neutral Pion Hadron Calorimeter (JLab Hall C 12 GeV) Yekaterina Gilbo The neutral pion's properties and the additional strange quark in the kaon are opportune to study the proton's substructure through General Parton Distributions (GPDs), which describe the movements, placements, and momenta of the quarks inside the proton. In pion or kaon electroproduction a neutral pion or kaon is produced. The neutral pion has a short mean lifetime and decays into two real photons. To study the structure of the proton, we have to analyze the neutral pion and the kaon and their decay products, and thus need dedicated detectors. For the neutral pion, a hadronic calorimeter can be placed in the decay photons' trajectory. For the kaon reaction, the most efficient detection method is an aerogel Cerenkov detector. Both cases rely on detector performance, and thus it is important to evaluate the conceptual design and all components of the detector carefully. In this presentation I will present results of conceptual design studies for the p$^{\circ}$ hadron calorimeter and of a new method based on biological techniques to evaluate the aerogel material index of refraction for the kaon detector. [Preview Abstract] |
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EA.00056: Beam characterization and optimization using a tunable Iris Aperture S.A. Graves, R.L. Kozub, D.W. Bardayan Successful reaction studies with radioactive beams require optimization of both the beam tune and detector placement. Some experiments require placing detectors close to the beam axis, and thus in potentially harmful positions, while the beam is being tuned. Other experiments benefit from some detector shielding that cannot necessarily be estimated beforehand. A good solution can often be achieved by an appropriate placement of an Iris Aperture (i.e., a circular collimator with a variable diameter) in the target chamber. Although this device is useful for shielding detectors, e.g., while tuning the beam at the beginning of an experiment, it is difficult to determine the exact size of the opening while it is under vacuum. A control module for the motor and screw drive system has been built that allows an operator to open and close the Iris Aperture from outside the vacuum. Using LED indicators, the module also provides information on the size of the aperture opening. Details will be presented. This research is supported by the U. S. Department of Energy. [Preview Abstract] |
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EA.00057: Table of isotopes as a teaching tool Johnathan Gross, Artemis Spyrou, Zach Constan, Michael Thoennessen A large number of middle and high school science teachers are visiting the National Superconducting Cyclotron Laboratory every year to participate in a variety of available outreach programs. After these visits the teachers often go back to their schools and would like to share their experiences at the laboratory with their students. These efforts are in many cases supported by the laboratory faculty and staff. One object that was requested by many of these teachers is the ``Chart of nuclei,'' which they can post in their classrooms. The standard copies of this chart are very technical and provide information that is not very useful for an introductory discussion of nuclear science in high schools. For this reason we have developed a specialized version of the Chart of Nuclei, modified to be suitable for a high school classroom. First samples of this work will be presented. [Preview Abstract] |
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EA.00058: Calibration of the MoNA and LISA Arrays for the LISA Commissioning Experiment A. Grovom, J. Kwiatkowski, W.F. Rogers The new LISA (the Large-area multi-Institutional Scintillator Array) neutron detector array, designed to be used in conjunction with MoNA (Modular Neutron Array) at the NSCL was recently commissioned in an experiment designed to investigate excited states of neutron-rich Oxygen isotopes near the neutron drip-line. In order for the trajectories of neutrons arising from decay to be determined with sufficient precision to allow reconstruction of the invariant mass of the decaying system, all 288 scintillator bars must be precisely position-calibrated and time-synchronized to within a few tenths of a nanosecond, and the time origin for neutron time-of-flight determination must coincide precisely with the secondary beam particle/target interaction. The former was accomplished using cosmic muons passing through the array, and the latter using detection of gamma-rays produced at the target in each of the 18 layers of the MoNA-LISA array. Several Root C++ macros were developed in order to produce these calibrations. Results for the LISA commissioning run experiment will be presented. [Preview Abstract] |
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EA.00059: DarkLight Detector Energy Deposition and Temperature Study Thoth Gunter Dark matter is thought to make up more than half of the total mass of most galaxies, the effects of which can be seen through astrophysical observations and can explain anomalies which would otherwise clash with the general understanding of physics. The Detecting A Resonance Kinematically with eLectrons Incident on Gaseous Hydrogen Target (DarkLight) experiment will investigate the existence of a dark matter force carrying particle, the A-prime (A') boson, through the study of electron-proton collisions. The experiment aims to find the A' boson by looking for a resonance peak within the electron-positron invariant mass spectrum. The DarkLight experiment is a proposed experiment to be run at Jefferson Laboratory's Free Electron Laser. This study preforms an initial investigate on the energy deposition and temperature change with in the sensitive volumes of the detector. The results of this study will be used to further design DarkLight's detector. [Preview Abstract] |
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EA.00060: Reconstructing Drell-Yan Data at SeaQuest Tyler Hague SeaQuest is a fixed target experiment at Fermi National Accelerator Laboratory. Using the 120-GeV main injector, SeaQuest will study the nucleon sea through proton-proton and proton-deuterium Drell- Yan reactions. Measurements on d-bar/u-bar ratios, as well as parton energy loss and the EMC Effect will be obtained using the Drell-Yan process of muon pair production. The MySQL database for SeaQuest and a new approach utilizing database commands for track reconstruction will be described. Reconstruction occurs within the database using dynamically created queries to create temporary tables. These are used to construct partial tracks at each station that can be combined into full tracks. Typically the wire chambers at each station will be used for tracking and the hodoscopes will be used for the trigger. In addition, track reconstruction with only hodoscopes is being developed for monitoring hodoscope efficiencies. [Preview Abstract] |
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EA.00061: Measuring the Half-Life of $^{60}$Fe Data Analysis Quinn Hailes $^{60}$Fe is a galactic gamma-radioactive isotope that is a signature of stellar nucleosynthesis. $^{60}$Fe can be found in deep-sea crust that could be a signature of possible recent nearby supernovae activity to the solar system. If the half-life of $^{60}$Fe is accurately measured we can assess how far from the earth a supernova occurred and precisely date how long ago it transpired. The half-life of radioactive isotope $^{60}$Fe has an accepted value of 2.62 x 10$^{6}$ yr. This new value measured at the Technical University of Munich is in contradiction to the previously accepted value of 1.49 x 10$^{6}$ yr. Our new experiment is to re-measure the half-life of $^{60}$Fe through Accelerated Mass Spectroscopy (AMS) and a low level counting station to eliminate some of the background radiation and other error in the accepted value. In my presentation I will talk about the data analysis for the activity of $^{60}$Fe. [Preview Abstract] |
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EA.00062: A Cryostat for the Development and Testing of Detector Readout Electronics in the \textsc{Majorana Demonstrator} Erin Hansen, Alan Poon, James Loach The \textsc{Majorana Demonstrator }will search for neutrinoless double beta decay in the isotope Ge-76 using a large array of germanium detectors deployed underground in ultra-low-background cryostats. The demands on the material radio-purity and the performance of the readout electronics are substantial. A novel vacuum cryostat has been constructed to house prototype \textsc{Majorana} front end electronics boards, simulating their interactions with a Ge detector and allowing measurements to be made of their performance at variable cryogenic temperatures. The cryostat will be used to refine the electronics design and to characterize the finished boards. The cryostat allows the boards to be tested rapidly, in realistic conditions and in an ultra-clean environment. [Preview Abstract] |
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EA.00063: Experimental Perspective on Electron-Proton Scattering at the Electron-Ion Collider Laura Havener The Electron Ion Collider is a proposed accelerator designed to study the quark and gluon substructures of nucleons and nuclei. Initial theoretical development of the collider kinematics for elastic electron-proton collisions has been accomplished, but actual experimental setups need to be considered. A major difficulty lies in experimentally differentiating elastic from inelastic scattering. This distinction is clearly defined in theoretical calculations but the difference becomes blurred in reality. ROOT Data Analysis Framework was used to determine how to effectively separate these collisions by investigating the decay of the hadronic state from inelastic scattering into a proton and a pion. Then the locations of the scattered products from both collisions were analyzed with respect to the already proposed experimental setups for the EIC. [Preview Abstract] |
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EA.00064: Recoil Mass Separator Hysteresis Measurements and Germanium Detector Development Robert Heitz A recoil mass separator, St. George, was proposed to study energy production and nucleosynthesis in stellar and explosive helium burning. To filter out background radiation and select the correct momentum for a charged beam, dipole magnets will be used to bend the beam. It is not possible to measure the magnetic field within the magnet without interfering with this beam. For this reason a hall probe was used to measure the magnetic field outside of the dipole magnet. Data taken comparing the magnetic field reading on this hall probe to that on a nuclear magnetic resonance probe in the center of the magnet, show the hall probe is sufficient to determine the magnetic field inside the dipole magnet. Complementing the St. George mass separator is the Georgina project. This project will be used to study stellar burning by efficiently detecting gamma rays at low energies. In order for the germanium detectors to operate correctly they need to be cooled down to liquid nitrogen temperatures. This is done by filling the detectors with liquid nitrogen and refilling the detectors every six hours. To allow for continuous use of the Georgina project, labview code was printed on a CampactRIO system to fill the germanium detectors at specified offset times. [Preview Abstract] |
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EA.00065: Modeling the Effects of Mirror Misalignment in a Ring Imaging Cherenkov Detector Tawanda Hitchcock, Austin Harton, Edmundo Garcia-Solis The Very High Momentum Particle Identification Detector (VHMPID) detector is planned as an upgrade for the ALICE experiment at the LHC. This detector identifies charged hadrons in the range of 5 GeV/c to 25 GeV/c momentum range. The VHMPID uses a Ring Imaging Cherenkov (RICH) detector to determine the particle velocity. This is accomplished by focusing the Cherenkov radiation generated by a relativistic charged particle onto a photon detector using a 24 segment mirror and calculating from that image the Cherenkov angle. This velocity information coupled with the particle momentum allows the particle mass to be calculated. A major issue in the RICH detector is that changes in temperature, humidity and other environmental conditions can cause movements in mirror position leading to errors when determining the Cherenkov angle. In this poster we will model the effects of mirror misalignment using a commercially available optical modeling software package. This will include quantifying the effects of both rotational and translational mirror misalignment for the initial assembly of the module and later on particle identification. [Preview Abstract] |
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EA.00066: Conceptual Design and Data Acquisition Techniques (JLab Hall C 12 GeV Kaon Aerogel Detector) Nathaniel Hlavin The additional flavor degree of freedom in the H(e,e'K$^{+})\Lambda $ and H(e,e'K$^{+})\Sigma ^{o}$ reactions provides a unique opportunity to study the reaction mechanism underlying strangeness production and the transition from hadronic to partonic degrees of freedom in exclusive processes. However, due to experimental challenges the potential of these reactions has not been fully exploited to date. One such challenge is the separation of kaons from pion and proton backgrounds. At high momenta, a kaon aerogel Cerenkov detector is the simplest and most economical way of addressing this issue. At CUA, we are building such a detector for Hall C at the 12 GeV Jefferson Lab. Desirable properties are high light output for kaons, and good efficiency in the collecting and converting the light using cost-effective PMTs. I will present the findings from physics simulations performed for the conceptual design and ongoing component testing, with focus on data acquisition techniques. [Preview Abstract] |
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EA.00067: Studying the Light Antiquark Asymmetry in the Nucleon Sea with FNAL E-906/SeaQuest Kristin Holz Fermilab's E-906/SeaQuest experiment will improve our understanding of the structure of the proton using Fermilab's 120 GeV Main Injector. Protons are collided with liquid hydrogen and liquid deuterium targets to measure the cross section ratio for the Drell-Yan di-muon process. From this ratio, SeaQuest will extract the anti-down to anti-up quark ratio as a function of Bjorken-x up to approximately 0.45. This measurement extends the results of the FNAL E-866/NuSea experiment, that measured the light antiquark asymmetry up to approximately x = 0.3. The momentum of the muons produced in the collisions is measured using a two magnet spectrometer and a four-station detector consisting of hodoscopes and wire chambers. SeaQuest will have greater statistical precision than E-866, in particular in the Bjorken-x region above 0.2, where the past experiment indicated the dbar/ubar ratio approaching unity. This presentation will give an update on the E-906/SeaQuest experiment, including the status of data taking and goals. [Preview Abstract] |
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EA.00068: Construction, Testing, and Analysis of Radon Mitigation System Dan Jardin, Richard Schnee The search for dark matter or other rare events such as neutrinoless double-beta decay is difficult in the presence of background radiation such as the alpha and beta emissions from the 222Rn decay chain. In order to reduce the radioactive background from Rn-daughters, an ultra-low radon clean room is being built at Syracuse University. A vacuum-swing adsorption system is used to mitigate the radon. Air flows through one of two tanks filled with charcoal that the radon adsorbs to, allowing the filtered air to pass into the clean room. Computer-controlled valves direct the airflow so that one tank filters the air while the other tank is purged of radon by circulating a small fraction of the cleaned airflow back through the tank at low pressure. The durations, pressures, and flow rates of each stage of building pressure, filtering, releasing pressure, and purging in the tanks are optimized in order to maximize the reduction of radon from the air. [Preview Abstract] |
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EA.00069: PIXE Analysis of Indoor Aerosols Christopher Johnson, Colin Turley, Robert Moore, Maria Battaglia, Scott LaBrake, Michael Vineyard We have performed a proton-induced X-ray emission (PIXE) analysis of aerosol samples collected in academic buildings at Union College to investigate the air quality in these buildings and the effectiveness of their air filtration systems. This is also the commissioning experiment for a new scattering chamber in the Union College Ion-Beam Analysis Laboratory. The aerosol samples were collected on Kapton foils using a nine-stage cascade impactor that separates particles according to their aerodynamic size. The foils were bombarded with beams of 2.2-MeV protons from the Union College 1.1-MV Pelletron Accelerator and the X-ray products were detected with an Amptek silicon drift detector. After subtracting the contribution from the Kapton foils, the X-ray energy spectra of the aerosol samples were analyzed using GUPIX software to determine the elemental concentrations of the samples. We will describe the collection of the aerosol samples, discuss the PIXE analysis, and present the results. [Preview Abstract] |
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EA.00070: Finding the Incompressibility of Nuclear Matter Jennifer Kachel The incompressibility coefficient is an important ingredient of nuclear matter's Equation of State and is significant to understanding neutron stars, supernova explosions and heavy ion collisions. Nuclear matter's incompressibility (K$_{nm})$ can be determined from the energy of the isoscalar Giant Monopole Resonance theory of nuclei: a collective mode of the nucleus in which the protons and neutrons oscillate in phase. We determined the compressibility coefficients for a set of nuclei using data for the energy of the monopole resonances and the mass radii. Using an A$^{-1/3}$ expansion analogous to that of the mass formula we extract K$_{nm}$. Upon examination of the coefficients of the expansion, it becomes evident that more data is needed to deduce an accurate value for K$_{nm}$. [Preview Abstract] |
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EA.00071: Analyzing aCORN Experiment Data Robert Kosar A precise measurement of the electron-antineutrino angular correlation coefficient in neutron beta decays, parameterized by ``a'', can be used to test the standard electroweak model. The aCORN collaboration will measure ``a'' to 1{\%} uncertainty. aCORN employs a kinematic approach to divide decays into two classes; the relative probability of a decay being in each class is related to ``a''. The results of aCORN's preliminary data run, completed last spring, are being analyzed to prepare for the physics run starting in February 2012. An algorithm to extract ``a'' from the data and the effects of the experimental parameters on the measured value of ``a'' are discussed. [Preview Abstract] |
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EA.00072: Testing and Characterization of Acrylic for the Daya Bay Reactor Neutrino Experiment Michael Krohn, Bryce Littlejohn, Karsten Heeger The Daya Bay reactor antineutrino experiment will determine the last unknown neutrino mixing angle T13 with a sensitivity of .01 or better. The measurement of T13 is important for theoretical model building and for possible searches of CP violation in the neutrino sector. Poly(methyl methacrylate), otherwise known as acrylic, is an important component for the construction of the target vessels in the antineutrino detectors and we have performed multiple tests that determined its unique properties. My project has been to understand the properties of acrylic in order to minimize systematic errors and test mechanical and materials compatibility issues in the Daya Bay reactor antineutrino experiment. These tests address both the mechanical and technical issues of the detector as well as the systematic affects introduced by the acrylic. [Preview Abstract] |
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EA.00073: Calibration of the Sweeper Chamber Charged-Particle Detectors for the LISA Commissioning Experiment J. Kwiatkowski, A. Grovom, W. Rogers The new LISA (Large-area multi-Institutional Scintillator Array) neutron detector array, designed to be used in conjunction with MoNA (Modular Neutron Array) was recently commissioned at the NSCL in an experiment designed to investigate excited states of neutron-rich Oxygen isotopes near the neutron drip-line. Charged fragments resulting from the neutron decays were swept out of the beam direction by the Sweeper Magnet after which they passed through a series of charged-particle detectors for fragment trajectory and energy determination. In order to achieve isotope separation and identification at the focal plane, which is then used to reconstruct the invariant mass of the unbound states, precise determinations of the fragment and neutron energies and trajectories are required. To correct for time-drifts in the charge-particle detectors that develop over the entire length of the experiment, Root C++ macros were developed to analyze and precisely correct for these detector drifts to within few tenths of a nanosecond. Root macros were also developed to position calibrate the ion chamber and CRDC's. Results for the LISA commissioning run will be presented. [Preview Abstract] |
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EA.00074: A systematic study of the sensitivity of triangular flow to the initial state fluctuations in relativistic heavy-ion collisions Rolando La Placa, Hannah Petersen, Steffen Bass At sufficiently high temperatures and densities, QCD matter forms a deconfined state called the quark gluon plasma (QGP). This state of matter can be created in collisions of ultra-relativistic heavy-ions, e.g. at the Relativistic Heavy Ion Collider. Due to its short lifetime, many QGP properties can only be inferred indirectly through a comparison of the final state measurements with transport model calculations. For our investigation we use a hybrid transport model based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport approach using an ideal hydrodynamic expansion for the hot and dense stage. Using UrQMD initial conditions for an Au-Au collision, particles resulting from a collision are mapped into an energy density distribution that is evolved event-by-event with a hydrodynamical calculation. By averaging these distributions over different numbers of events, we studied how the granularity of the distribution affects the initial eccentricity, the initial triangularity, and the resulting flow components. The average elliptic flow in non central collisions is not sensitive to the granularity, while triangular flow is. The triangularity might thus provide a good measure of the amount of initial state fluctuations necessary to reproduce the experimental data. [Preview Abstract] |
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EA.00075: Monte-Carlo Simulations of Near-Threshold $\gamma + n \rightarrow p + \pi ^- $ Measurements at MAX-lab Samuel Lipschutz Unlike classical regimes of physics, nuclear physics does not yet have a complete theoretical description. To scrutinize the validity of theoretical constructions (such as ChPT) accurate experimental data need to be obtained. Currently, a measurement of the total cross section for $\gamma + n \rightarrow p + \pi ^- $ is underway at MAX-lab in Lund, Sweden, using a liquid deuterium target. The resulting $\pi ^-$ is detected by its subsequent capture and photoemission by a deuteron through $\pi ^- + d \rightarrow 2n + \gamma$. Several large sodium iodide spectrometers detect this emitted photon. Since this experiment deals with an extended target, there are several key quantities that need to be investigated by simulation. The experimental geometry was reproduced in a GEANT simulation where, among other parameters, the fraction of $\pi ^- s$, which do not undergo recapture in the target and the detector acceptances from the extended target were examined. Preliminary results will be shown. [Preview Abstract] |
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EA.00076: Simulation of GRETINA Lifetime Experiment Cody Littley, Hironori Iwasaki, Antoine Lemasson In order to understand properties of exotic atomic nuclei, the research group has developed a method to measure the rate of decay of excited states in certain unstable isotopes, for example 66Fe [1]. By measuring the Doppler shift of gamma rays with a so-called plunger device [1] it is possible to deduce with great accuracy the excited-state lifetime. This technique, which is called the Recoil Distance Doppler-shift Method, has precision on the order of one pico second. I will present the development a simulation software package which will help the research team to quantize and to analyze the data from experimental runs. This software is based upon existing software which was used for simulations of the SeGA project. It has been modified to support the GRETINA detector, which is used in the experimental setup for the lifetime measurements. The software makes use GEANT and ROOT toolkits, which are essential for the calculations of the interactions of particles with the detector and the recording of that data.\\[4pt] [1] W.Rother et al., Phys. Rev. Lett. 106 (2011) 022502 [Preview Abstract] |
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EA.00077: Measurements of gamma radiation levels and spectra in the San Francisco Bay Area B.T. Lo, K.P. Brozek, C.T. Angell, E.B. Norman Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are $^{214}$Bi, $^{40}$K, and $^{208}$Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions -- such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from $^{134,137}$Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed. [Preview Abstract] |
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EA.00078: Study of Energy Resolution of Lead Glass Calorimeter Daniel Lombardo In the proposed experiment at Jefferson Lab, Gep(5), the structure of the proton will be studied by measuring the proton elastic form factors. In order to ensure that the scattering events are elastic, the proton angle and energy will be measured with a magnetic spectrometer and the electron angle and energy will be measured with a lead glass calorimeter, called BigCal. An aluminum sheet, 20cm thick, is typically placed in front of BigCal to shield the calorimeter from unwanted radiation, but this causes a loss of resolution in the measured energy. A simulation was carried out to determine whether replacing the shield with radiation hardened lead glass would significantly improve the resolution of the calorimeter. The simulation was run with the aluminum shield in place, and then again with the new radiation hard lead glass shield. Comparing the measured energies between the two different shields it was found that the resolution improved by a factor of 2 with the lead glass shield at an electron energy of 4.6 GeV. The resolution continued to increase at lower values of the electron energy. This improvement in resolution will be useful in isolating elastic scattering events in the trigger for BigCal. [Preview Abstract] |
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EA.00079: Creation of Thin Deuterated Polyethylene Targets for Inverse Kinematics Transfer Reaction Measurements K.D. Long, R.L. Kozub, B. Manning, S.D. Pain, C.D. Nesaraja, M.S. Smith, D.W. Bardayan Transfer reactions are an important tool for the study of single-particle structure of nuclei. Such measurements have many applications to the field of astrophysics, such as study of the rapid neutron capture (r-) process that is believed to create heavy elements in supernovae. Measurements in inverse kinematics are necessary when studying transfer reactions on unstable nuclei with lifetimes too short to be used as targets. The measurement of deuteron-induced transfer reactions in inverse kinematics requires a target containing a significant quantity of deuterons, such as deuterated polyethylene ((C$_2$D$_4$)$_n$ or CD$_2$), which can be fabricated into thin foils by dissolving CD$_2$ in xylene. A campaign is underway at ORNL to measure (d,p) reactions with unique heavy fission fragment beams. For such measurements, thin targets are favored to minimize peak broadening in the energy spectra of emitted particles. Emphasis has been placed on creation of targets of $\sim$70 $\mu$g/cm$^2$ thickness, significantly thinner than previously used at ORNL. Improvements, such as careful control of the temperature of slides covered by the CD$_2$/xylene solution, have been developed to produce such targets. Details will be presented. This research is supported by the Office of Nuclear Physics in the U. S. Department of Energy. [Preview Abstract] |
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EA.00080: A New 3He-Target Design for Compton Scattering Experiment S. Mahalchick, H. Gao, G. Laskaris, W. Weir, Q. Ye, Q.J. Ye The neutron spin polarizabilities describe the stiffness of the neutron spin to external electric and magnetic fields. A double-polarized elastic Compton Scattering experiment will try to determine the neutron spin polarizabilities using a new polarized $^3$He target and the circularly polarized $\gamma$-beam of HI$\gamma$S facility at the Duke Free Electron Laser Laboratory (DFELL). To polarize the $^3$He target, a newly constructed solenoid is being used which can provide a very uniform magnetic field around the target area and allows to place High Intensity Gamma Source NaI Detector Arrays (HINDA) closer to the target. The ideal target polarization is 40-60\% and will be measured using the nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) techniques. A prototype of the polarized $^3$He target is being constructed in the Medium Energy Physics Group laboratories at Duke and is currently being tested. The experiment is expected to take place in 2013 after the DFELL upgrade. I will be presenting details of the construction process, including design specifications and data from the magnetic field mapping, as well as preliminary target polarization results. This work is supported by the US Department of Energy, under contract number DE-FG02-03ER41231, and by the National Science Foundation, grant number NSF-PHY-08-51813. [Preview Abstract] |
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EA.00081: Conductance Control Iris for the K150 Cyclotron H- Ion Source Armando Maldonado, Henry Clark, Gabriel Tabacaru A multi-cusp H- ion source has been installed on the K150 cyclotron for the production of high intensity proton beams. These beams will be used to create secondary radioactive ions for the Upgrade Project [1]. One of the limiting factors in creating an intense beam comes from poor vacuum along the injection line caused by the ion source itself. A large flow of hydrogen gas is required to make the Hydrogen negative (H-) ions in the ion source. As a result, many of the hydrogen molecules exit the ion source and migrate into the injection line and deteriorate the vacuum. To reduce the flow of these molecules into the injection line, a computer controlled iris will be installed between the ion source and the injection line. With the iris set at the correct diameter, the vacuum in the injection line should improve the transport efficiency of the H- ions to the cyclotron inflector should increase. For the project we used an 8'' OD Conflat DVM brand iris with an MDrive 17 Plus motor which will be controlled by a Labview software interface. [Preview Abstract] |
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EA.00082: Study of Hot QCD Matter Using QCD Jets as a Tomographic Probe of the Matter at the LHC Sultan Malik, Peter Jacobs, Bo Fenton-Olson Quantum chromodynamics (QCD) predicts that at very high temperatures, nuclear matter undergoes a phase transition from its normal hadronic gas state to a deconfined partonic phase called the quark-gluon plasma (QGP). This state of matter is generated in high energy collisions of heavy atomic nuclei. QCD jets are correlated sprays of hadrons arising from a hard partonic momentum transfer during the initial phase of the collision. Jets interact strongly with the hot QCD medium, leading to a marked modification of their structure. This phenomenon, known as ``jet quenching,'' provides unique probes of the QGP. This analysis presents a new approach to jet quenching, utilizing the coincidence of a trigger hadron with a recoil jet. Jets are reconstructed using state-of-the-art tools and the underlying event background, intrinsic to heavy ion collisions, is assessed in detail. By using simulated Pb+Pb and p+p events, the new approach is validated. We investigate the applicability of this method to measurements by the ALICE experiment at the LHC (Large Hadron Collider). [Preview Abstract] |
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EA.00083: Simulation of an Apparatus to Measure the Parity-Violating Neutron Spin Rotation in $^{4}$He R.C. Malone, B.E. Crawford In order to better understand the nucleon-nucleon weak interaction, the Neutron Spin Rotation (NSR) collaboration performed an experiment at NIST that measured a parity-violating neutron spin rotation per unit length in liquid helium of $\sim$[1.7$\pm $9.1(stat.)$\pm $1.4(sys.)] x 10-7 rad/m [1]. A second experiment is planned using a more intense neutron beam to reduce the statistical uncertainty, which was the limiting source of uncertainty in the measurement. This project focused on analysis of systematic effects in the experiment using a Monte Carlo computer simulation which traces neutrons down the beamline, calculating scattering from target materials, reflections from neutron waveguides, and rotations due to magnetic fields. Systematic effects resulting from small angle scattering coupled with different target locations and beam geometries were studied. \\[4pt] [1] W.M. Snow, \textit{et al.}, Phys. Rev. C \textbf{83}, 022501 (2011). [Preview Abstract] |
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EA.00084: Investigations of multi-particle exit channels of levels in light nuclei J.J. Manfredi, R.J. Charity, J.M. Elson, R. Shane, L.G. Sobotka, Z. Chajecki, D. Coupland, H. Iwasaki, M. Kilburn, J. Lee, W.G. Lynch, A. Sanetullaev, M.B. Tsang, J. Winkelbauer, M. Youngs, S.T. Marley, D.V. Shetty, A.H. Wuosmaa, T.K. Ghosh, M.E. Howard The HiRA array was used to study the many-particle exit channels produced from the interactions of an $E/A$ = 70 MeV $^{9}$C beam with a $^{9}$Be target. Correlations between these particles were studied to analyze the decays, particularly whether they occur in one prompt step or sequentially through long-lived intermediates. The five-body decay of $^{8}$C is found to occur in two steps of two proton decay through a $^{6}$Be ground-state. In the first step, the correlations between the protons clearly show the enhanced diproton character of the decay, and the second step was found to be consistent with the independently measured $^{6}$Be two-proton decay. A new mass and uncertainty for $^{8}$C were deduced from these data and used in a refit of the A = 8 data to the isobaric multiplet mass equation (IMME). The fit indicates the need for terms beyond quadratic meaning that isospin symmetry is clearly broken for the A = 8 multiplet. [Preview Abstract] |
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EA.00085: Discovery of Isotopes Erin May, Michael Thoennessen To date, no comprehensive study has been undertaken regarding the initial detection and identification of isotopes. At NSCL, a project has been initiated to catalog and report the initial observation of every isotope. The conditions characterizing the successful discovery of an isotope include a clear and unambiguous mass and element identification through decay curves, mass spectroscopy, gamma-ray spectra, and/or relationships to other isotopes, as well as the publication of such findings in a refereed journal. I will present the documentation for eight elements: cesium, lanthanum, praseodymium, promethium, samarium, europium, gadolinium, and terbium. The year and author of each initial publication along with the location and methods of production and identification will be shown. A summary and overview of all $\sim $3000 isotopes documented so far as a function of discovery year, method and place will also be presented. [Preview Abstract] |
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EA.00086: Nuclear Physics with CLAS12 and the High Threshold Cherenkov Counter Jeffrey Mazurek New construction is underway at Thomas Jefferson National Lab for the 12 GeV upgrade to the Continuous Electron Beam Accelerator Facility (CEBAF) and the CEABF Large Acceptance Spectrometer detector upgrade (CLAS12) at Hall B. This upgrade allows a broad experimental program with the new CLAS12 detector to map the nucleon's 3-dimensional spin and flavor content through the measurement of deeply exclusive and semi-inclusive processes. During an experiment, CLAS12 will record data when its High Threshold Cherenkov Counter (HTCC) identifies a scattered electron through the generation of Cherenkov Light. Cherenkov Light indicates an event and is created when a charged particle moves faster than the speed of light in a medium. The HTCC uses a system of 48 ellipsoidal mirrors assembled into one circular, 8-ft diameter mirror to capture this light. While both pions and electrons can generate Cherenkov Light, only that from an electron identifies an event. Therefore, the HTCC must distinguish the light of a scattered electron from the light by pion contamination. This paper offers an overview of Jefferson National Lab's new CLAS12 detector and a detailed presentation of the HTCC. [Preview Abstract] |
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EA.00087: Gas Electron Multiplier Tracking Telescopes for OLYMPUS Joshua McMahon, Miles Campbell The OLYMPUS collaboration is conducting an experiment to measure two-photon contributions to elastic electron scattering. The experiment is taking place at the DORIS storage ring at DESY, Hamburg, Germany using the upgraded BLAST detector from the MIT-Bates Linear Accelerator Center. Gas Electron Multiplier (GEM) telescopes are used to detect scattered leptons at a forward angle to monitor the luminosity. The GEM detectors have been commissioned at the test facility at DESY and were installed along with the main detector in the DORIS storage ring. With the testbeam the performance characteristics such as gain, efficiency, multiplicity, and resolution of the GEMs were studied. [Preview Abstract] |
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EA.00088: Analysis of the 4He target density for Jefferson Lab Short Range Correlations (SRC) experiments Nicholas McMahon A series of Short Range Correlations experiments aiming to study the interactions between nucleons inside 4He nuclei ran in Hall A of the Thomas Jefferson National Accelerator Facilily (TJNAF) between February and May of 2011. My work consists on the study of the density of the 4He gas target. The Target conditions were set to pressures between 190 and 210 PSI and tempertures between 18 and 20 K. My work shows that virial corrections to the target density taking care of the deviations from an ideal gas model are up to 2\%. An additional study showed how slowly target heating increased along with the beam current between 5 and 60 uA. [Preview Abstract] |
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EA.00089: Analyzing Detector Acceptance for Design Optimization Kathryn Meehan Both the unsolved mystery of 26\% of our universe that is dark matter as well as other observed astrophysical anomalies have motivated theories that go beyond the standard model and predict the existence of an A' boson. This particle is theorized as the carrier of a ``dark force'' that couples with electromagnetism. The Free Electron Laser at Jefferson Laboratory will be used to create an e-p collision that will allow the DarkLight detector to detect the A' boson if it occupies the relevant parameter space. To detect the A' boson, detectors need to be placed at locations that would maximize the signal and minimize background processes such as e- + e- $\to$ e- + e- (Moller scattering) and e- + p $\to$ e- + p (e-p scattering). The computer program ROOT is used to calculate the acceptance and efficiency of the detector for different cuts on the angles of outgoing particles. Efficiency plots were generated for a realistic detector cut. [Preview Abstract] |
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EA.00090: Production of High-Purity Germanium Ingots for Detector-Grade Crystal growth Hao Mei The growth of high-purity germanium crystals is needed for planned DUSEL experiments. Many steps are required convert bulk germanium into a gamma-ray spectrometer. The electronic-grade polycrystalline germanium starting material is zone refined in a synthetic silica crucible inside a graphite boat enclosed within a quartz tube filled with hydrogen. Ingots of impure germanium approximately 60 cm long are held horizontally in a graphite boat as a radio frequency (RF) coil surrounding the quartz tube melts a small vertical section of the ingot. As the ingot is slowly drawn through the fixed coil, the trailing solid is more pure than the adjacent liquid. Therefore, the last liquid to solidify at the ingot's end contains an increased impurity level. Since the impurities concentrate in the molten section, the repeated and sequential melting from one end towards the final end, sweeps the impurities to the ingot's final end. This sweeping operation is repeated many times until the impurities are concentrated at one end of the ingot. This final end is then removed to leave the desired higher-purity portion. Production rates can be increased by drawing multiple ingots through multiple coils within one hydrogen-filled quartz tube. Purity is then determined by a Hall Effect measurement.During year one, a currently available 30 KVA Induction Generator will be used to develop the zone technique above ground. [Preview Abstract] |
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EA.00091: Development of Testing Equipment for Aerogel and Large-Diameter PMTs Michael Metz The 12GeV upgrade at the Jefferson Laboratory particle accelerator allows for unique new opportunities to study hadron structure. In particular, the kaon electroproduction reaction provides new insights on the transition from the hadronic to partonic degrees of freedom. To study hadron structure through kaon production in Hall C at JLab a new detector is needed. A threshold aerogel detector that uses the emission of Cerenkov radiation to filter kaons from backgrounds of other particles is thus being built at CUA. In order to distinguish kaons from pions and protons at the desired momentum ranges of 2-4 GeV/c and 4-6 GeV/c, aerogel at indices of refraction n = 1.030 and 1.020 is required, respectively. Additionally, photomultiplier tubes are required to effectively detect the emitted radiation. In this presentation I will demonstrate the design of the new equipment I developed for testing the detector components and results from commissioning it. [Preview Abstract] |
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EA.00092: Magnet Construction for Neutron Interferometry Rob Milburn, Chris Crawford The study of neutron interferometry highlights some of the essential components of quantum mechanics allowing us to study the wave-like nature of the neutron. The spin of polarized monochromatic neutrons in an interferometer can be flipped by passing through a static B-field perpendicular to the holding field. Constraints on such a magnet are that the field must be constant within a cylindrical volume, but zero everywhere outside the coil. A double cosine theta coil has been designed and is currently undergoing construction. A comparison of the prototype's results to simulation results will be presented. [Preview Abstract] |
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EA.00093: Gain-Matching and Efficiency Tests On Double- and Single-Ended Hodoscope Arrays Andrew Miller E-906/SeaQuest is a fixed target experiment analyzing the ratio of anti-down to anti-up quarks in the nucleon sea of the proton as well as studying shadowing, anti-shadowing, and energy loss effects using the Drell-Yan process. The muon detector consists of a two-magnet spectrometer and 4 stations of drift chamber and hodoscope combinations. The hodoscopes are used to produce the fast trigger system for the spectrometer. In order to prepare the station 3 and 4 hodoscope arrays for the experiment, the PMTs were initially gain-matched by using a multichannel analyzer to record the spectra from a Cs137 radiation source and adjusting the voltage so the Compton edge occurred in the same channel. Once this was completed, cosmic ray rate tests were performed using various discriminator thresholds values to verify the chosen PMT voltages. This is critical as each 16-channel discriminator to be used must have a single threshold. Interesting effects observed in these rates due to nearby shielding will also be shown to illustrate the special difficulties in using cosmic ray muons for these tests. [Preview Abstract] |
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EA.00094: Verification of the Endcap Electromagnetic Calorimeter Implementation into the STAR Simulation Package Kevin Miller Spin experiments using the STAR detector at Brookhaven National Laboratory seek to measure the gluon contribution to the proton's spin. These measurements require the Endcap Electromagnetic Calorimeter (EEMC) to be well-modeled in the STAR simulation package. This analysis will confront simulations and data from proton-proton collision runs taken in 2006. Comparisons of quantities, such as cluster energy, opening angle, particle invariant masses, and hit distributions will be shown. [Preview Abstract] |
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EA.00095: Software Implementation for the Characterization of Silicon Pixel Detectors Kyle Miller, Ricardo Eusebi Pixel and Silicon-strip detectors are now a fundamental component for the detection, identification, and characterization of particles in nuclear and particle physics. They are used for beam diagnostics, for measurements of energy lost by electrons, for full-energy measurements of alphas and protons and heavy nuclei. The pixel and strip detectors are usually the most complex, sensitive, and expensive system in multi-million dollar detectors such as the ones in the Relativistic Heavy Ion Collider at Brookhaven. This poster describes the development of a characterization station for pixel and strip detectors in clean room at Texas A\&M University. As a first step we describe the quantities to be measured for a full characterization of the pixel sensor, the identification of the needed electronic circuitry and the logic behind the control and readout of the system as a whole. The second stage shows the analysis of the obtained results from a set of next-generation radiation-hard pixel sensors. [Preview Abstract] |
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EA.00096: A further measurement to test electron conversion theory: transitions produced following the $\beta$-decay of $^{116}$In Sondra Miller, John Hardy, Ninel Nica, John Goodwin Precise internal conversion coefficients (ICCs) are vital to the study of nuclear decay schemes, determining transition rates, spin and parity designations, and branching ratios. However, there are very few experimental tests of the calculated ICC's and in fact there are only $\sim$10 measurements available with errors of less than 1\%. Such a paucity of data complicates scientists' efforts to determine what theoretical calculations should be used to model the ICC. The goal of our present experiment is to determine the $\alpha_{k}$ for the 65.7-keV M4 transition in $^{119}$Sn. However, the energy of the $^{119}$Sn x-rays is below the energy range that our HPGe detector is accurately calibrated for. The $\beta$-decay of $^{116}$In populates states in $^{116}$Sn which produce a few strong transitions with well established conversion coefficients. This allows us to calibrate our detector at the energy of the Sn x-rays, which is an essential requirement for the measurement of the $^{119}$Sn ICC. [Preview Abstract] |
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EA.00097: Trigger Logic using memory bits for SeaQuest E - 906 Prajwal Mohanmurthy, Jin-Yuan Wu, Shiuan-Hal Shiu The SeaQuest $E-906$ at Fermi National Accelerator Laboratory is a fixed target Drell - Yan process experiment to measure the $\bar{u} \bar{d}$ asymmetry in proton quark sea using the proton beam from the main injector at $120GeV$. The SeaQuest trigger system consists of four hodoscope stations guided by a coincidence logic to select candidate Drell-Yan dimuon tracks. The trigger electronics involves a CAEN VME 1495 which is a FPGA implementation board. Two basic ways of implementing the trigger logic using FPGA are based either on the gate elements or on the memory bits. The feasibility of using digitized hodoscope signal output wires themselves to address the memory bits, in order to implement the SeaQuest $E-906$ trigger logic in the memory, was investigated. [Preview Abstract] |
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EA.00098: Monte Carlo Studies: Tagging Heavy Quark Initialized Jets Alyssa Montalbano Quark-Gluon-Plasma (QGP), a new quantum chromodynamic phase of matter made in heavy ion collisions composed of deconfined quarks and gluons, is studied at the Relativistic Heavy Ion Collider and its experiment PHENIX has plans to upgrade its detectors to study QGP properties in greater detail. Detailed measurements of modifications of heavy and light jets are needed to develop a coherent understanding of how different partons interact with QGP. Jets, hadrons resulting from high energy quarks or gluons, are used since they are color and energy calibrated probes of QGP. Leading order Monte Carlo event generator PYTHIA was used to generate p+p collisions and resulting charm and beauty jets. Realistic detector performance was accounted for using Geant4 based simulations. Tagging methods of distance of closest approach and determining secondary vertices were used to study tagging efficiency and rejection of light jets. Probability distributions of jets originating at the collision vertex were plotted. Results will lead to further development of tagging heavy flavor jets in high multiplicity Au+Au collisions and a new understanding of fundamental energy loss mechanisms within QGP. [Preview Abstract] |
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EA.00099: Optimizing Position Sensitivity of the Detection System for the St. George Recoil Mass Separator Luis Morales, Jerry Hinnefeld, Manoel Couder, Sunil Kalkal The St. George recoil mass separator at the University of Notre Dame will be used to study ($p$,$\gamma$) reactions of astrophysical interest. A detection system for use with St. George, which utilizes energy and time-of-flight to identify detected particles, is being developed at Indiana University South Bend. An electrostatic mirror assembly is used to deflect secondary electrons produced by the passage of an ion through a thin foil onto a microchannel plate (MCP) detector, which registers the start time for the time-of-flight measurement. Simulations of the transport of the secondary electrons from the foil to the MCP detector have been carried out using SIMION, in order to determine how well the position of the ion at the foil is preserved by the electrostatic mirror. The effective position resolution of the electrostatic mirror assembly has been found to be sensitive to the pitch of a wire grid that accelerates the secondary electrons away from the foil. Position sensitivity for both the start detector and the stop detectors of the time-of-flight system will allow corrections based on the ion trajectory. [Preview Abstract] |
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EA.00100: Study of charged pion elliptic flow and search for Electric Quadrupole Effect in Au+Au collisions at 39 GeV from STAR Lynn Mormino It is predicted that Chiral Magnetic Wave (CMW) at finite baryon density can induce an electric quadrupole moment of the quark-gluon plasma produced in heavy ion collisions. [1] This electric quadrupole deformation lifts the degeneracy between the elliptic flow ($v^{2})$ of positive and negative pions leading to $v^{2}(\pi _{+}) \quad < \quad v^{2}(\pi _{-})$. We study the difference between $v^{2}(\pi _{+})$ and $v^{2}(\pi _{-})$ measurements from STAR for Au+Au collisions at 39 GeV, and investigate the dependence of the $v^{2 }$difference on the measured net-proton number of the data sample. Here the net-proton number is used to approximate the conserved net-baryon number, and the $v^{2}$ difference is expected to be proportional to the baryon number asymmetry in the presence of an Electric Quadrupole Effect. In this work, we present pion elliptic flow as a function of transverse momentum and centrality for Au+Au collisions at 39 GeV, and we will discuss the dependence of the $v^{2}$ difference on net-proton numbers. \\[4pt] [1] Y. Burnier, D. Kharzeev, J. Liao and H. Yee, arXiv:1103.1307. [Preview Abstract] |
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EA.00101: Characterization of P-Type Point-Contact Detectors for the Majorana Demonstrator Project James Mulligan The Majorana Demonstrator is an experiment that will search for neutrinoless double beta decay in 76-Ge. Canberra's Broad Energy Germanium Detectors (BEGes) are commercial high purity germanium p-type point contact detectors that are of interest to the Majorana Demonstrator experiment. Point contact detectors have the ability to distinguish single-site events from multiple-site events and can use this capability to reject gamma-ray backgrounds in the detectors. Several detailed characterizations were performed on modified BEGe detectors, including analysis of multi-site interactions and investigation of performance as a function of bias voltage. Coincidence data were also taken using a scintillation detector in order to characterize the drift time of pulses from the germanium detector. [Preview Abstract] |
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EA.00102: Simulation of the CLAS12 dual hydrogen-deuterium target Christopher Musalo, Gerard Gilfoyle The primary mission of Jefferson Lab (Jlab) is to reveal the quark and gluon structure of nucleons and nuclei and to deepen our understanding of matter and quark confinement. This mission will be done using a 12-GeV electron beam incident on nuclear targets. One approved experiment E12-07-104 will measure the elastic scattering of electrons from deuterium to extract the neutron magnetic form factor ($G_M^n$) using the CLAS12 detector. Calibrations will be done with a dual, co-linear target consisting of liquid hydrogen($LH_2$) and liquid deuterium ($LD_2$) cells. The hydrogen target is used for calibration, and the deuterium one provides the data for the physics analysis. A CLAS12 simulation has been developed called gemc, where Geant4 is used to simulate the components of CLAS12. We have added the dual $LH_2-LD_2$ target to the gemc simulation. The targets parameters are stored in a mysql database and then read into the simulation at run time. Simulated particles start at a random point in the target volume and are propagated through the CLAS12 detector. We will present initial results showing the effect of target size and position on the distribution of hits in CLAS12. [Preview Abstract] |
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EA.00103: Efficiency of PHENIX Resistive Plate Chambers in RHIC $\surd$s = 500 GeV p+p Collisions Andrew Nederlof, Breet Fadem The PHENIX collaboration studies polarized proton proton collisions created by the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory to better understand the spin structure of the proton. In order to improve the rejection of the existing muon trigger and allow the measurement of single spin asymmetries from the decay of W bosons, PHENIX has added stations of Resistive Plate Chambers (RPCs) to the north and south forward arms of the detector. An additional set of stations closer to the collision vertex will be added for the 2012 run. This upgrade enhances PHENIXs ability to trigger on high pT single muons. Efficiency of the RPCs will be estimated by comparing tracks reconstructed by the pre-existing subsystems with hits in the RPCs. Progress on this effort will be reported. [Preview Abstract] |
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EA.00104: Search for induced depletion of $^{108m}$Ag with 6 MeV bremsstrahlung Kaatrin Netherton, Stanley Henriquez, Nino Pereira, Marc Litz, James Carroll The nuclide $^{108}$Ag has a complicated and not yet well understood energy structure with numerous excited states. One of these, $^{108m}$Ag, is a metastable state with a half-life of 418 years and a significantly higher energy than the ground state. The ground state has a 2.37 min half-life and a large $\beta ^{-}$ decay branch with Q$_{\beta -}$ = 1.649 MeV. While these traits make the isomer a good candidate for energy storage, the rarity of its natural decays makes it difficult to utilize its stored energy. Through irradiation of a $^{108m}$Ag source, it might be possible to bypass the natural decay path and induce an energy release by transferring population from the isomer to the ground state. The poster will describe the implementation of an automated system by which to perform repeated tests of $^{108m}$Ag depletion using 6 MeV bremsstrahlung and preliminary results will be given. [Preview Abstract] |
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EA.00105: ABSTRACT WITHDRAWN |
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EA.00106: Resistive Plate Chamber Assembly for the PHENIX Forward Trigger Upgrade Walker Nikolaus Measuring the contributions of sea quarks to the total spin of the proton is a prominent goal of the PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab (BNL). To enable PHENIX to measure these contributions, a trigger upgrade is needed to select the single high transverse momentum muons events. hese events are common in the decay of a W-boson. Studying particles created during proton collisions is the process being used to find spin contributions through the W-boson. A trigger upgrade is needed that can meet these requirements: high time resolution, high position resolution, cheap construction, and thin form. A Resistive Plate Chamber (RPC) fits the requirements. These RPCs are high rate detectors assembled meticulously to minimize noise and cross signals. These detectors are made up of multiple layers. Within an aluminum frame sits a readout plane between two layers of gas gaps both of which are covered with copper. There are short analog wires that connect to the side of the RPCs from the readout plane. This presentation will discuss in detail the overall assembly process of RPCs and the purpose of each component. [Preview Abstract] |
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EA.00107: Effective Boson Number- A New Approach for Predicting Separation Energies with the IBM1, Applied to Zr, Kr, Sr isotopes near A=100 Nancy Paul, Pieter Van Isacker, Jos\'e Enrique Garc\'Ia Ramos, Ani Aprahamian This work uses effective boson numbers in the Interacting Boson Model (IBM1) to predict two neutron separation energies for neutron-rich zirconium, strontium, and krypton isotopes., We determine the functional forms of binding energy and excitation energies as a function of boson number for a given choice of IBM parameters that give a good overall description of the experimental spectra of the isotopic chain. The energy of the first excited 2+ level is then used to extract an effective boson number for a given nucleus, that is in turn used to calculate the separation energies. This method accounts for complex interactions among valence nucleons around magic and semi- magic nuclei and successfully predicts the phase transitional signature in separation energies around A=100 for 92-108Zr, 90-104Sr, and 86-96Kr [1] References: [1] Ame2011-preview as downloaded from http://amdc.in2p3.fr/masstables/Ame2011int/filel.html. [Preview Abstract] |
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EA.00108: Energy Loss Calculations for Target Thickness Determinations using SRIM and Excel A.S. Pawlak, J.P. Greene The thickness of a thin target foil can be determined by measuring the energy loss of alpha particles that travel through it. In the Target Laboratory of the Physics Division at Argonne National Laboratory (ANL), this is accomplished by measuring the energy loss of the 5812 keV alpha particles emitted by a $^249$Cf source using a silicon detector set-up [1]. The energy loss is translated into the target foil thickness using the stopping power for $^4$He in the target material obtained from the stopping/range tables provided by SRIM. This calculation has until recently been carried out using a program developed for this purpose, ``ENELOSS.'' This program uses the stopping/range tables from the original work published by Ziegler [2]. Additionally, due to its design, ENELOSS is unable to easily accommodate targets made from compounds. In order to perform theses measurements using the most recent SRIM data, and to better calculate the thickness of compound targets, we have developed a ``Thickness Calculation'' spreadsheet using Microsoft Excel. This spreadsheet approach is not limited to elemental targets and employs stopping/range tables from the most recent edition of SRIM available on the web. The calculations obtained allow for more accurate target thicknesses and automates the process conveniently for repetitive measurements. This work was supported by the U.S. DoE, Nuclear Physics Division, under Contract No. W-31-109-Eng-38. [1] G.E. Thomas and J.P. Greene, NIMA \textbf{362} (1995) 201 [2] J.F. Ziegler, \textit{The Stopping and Range of Ions in Matter}, vols. 2-6, Pergamon Press, New York, USA, 1977-1980 [Preview Abstract] |
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EA.00109: Characterization and development of photocathodes using laser induced time-of-flight spectroscopy E. Ramirez-Homs, D. Velazquez, L. Spentzouris, J. Terry The emittance of a beam generated for use in particle accelerators is a critical performance parameter. In order to achieve peak performance, intrinsic transverse emittance on the order of 0.1mm-mrad is required. This initial emittance is about an order of magnitude lower than provided by today's sources. Several important efforts are being made to reach this lower emittance with cathode design modifications. A photocathode design study and implementation of experimental techniques for the characterization is proposed and discussed. [Preview Abstract] |
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EA.00110: Determining the Impact Parameter and Cross-Section in Heavy-Ion Collisions Andira Ramos, William Lynch, Betty Tsang, Rachel Hodges The collisions of Tin isotopes, $^{112,118,124}$Sn + $^{112,118,124}$Sn at E/A= 70MeV will be used to constrain the nuclear Equation of State at low densities. To identify central and peripheral collisions, the impact parameters and cross-sections for each reaction were calculated using charged particle multiplicities measured with the MSU Miniball/WU Miniwall array. The array consists of 160 CsI crystals covering around 72{\%} of the solid angle around the target. Each Miniball/Miniwall detector consists of a layer of thin plastic scintillator, followed by a CsI (Tl) scintillator, which is 3 cm thick for the Miniwall and 2 cm thick for the Miniball detectors. The number of charged particles from a collision that hit the Miniball/Miniwall array is defined as the multiplicity for that collision. The methodology for extracting the impact parameter from the multiplicity and the results of the Miniball/Miniwall analysis will be presented in this poster. [Preview Abstract] |
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EA.00111: Accelerator and cosmological constraints on low mass WIMP models compatible with DAMA and CoGeNT searches Clyde Redger, Gintaras Duda Recent dark matter experiments have generated much interest in light ($m_{DM} <15$ GeV) dark matter particles. The DAMA/LIBRA and CoGeNT direct detection experiments have detected signals that could be interpreted as a Weakly Interacting Massive Particle (WIMP) with a mass range of $m_{DM} \sim 5-10$ GeV and a WIMP-nucleon cross section of approximately $\sigma \sim 7\times 10^{-41}$cm$^{2}$. In addition, the Fermi Gamma Ray Space Telescope has detected gamma rays from the Galactic Center that, if interpreted as dark matter annihilations, imply a mass range of $m_{DM} \sim 7-10$ GeV. There are several dark matter models that can produce WIMPs in this region. We determine the viability of these models by subjecting them to current constraints from colliders and other direct detection experiments. [Preview Abstract] |
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EA.00112: Optical Attenuation in MoNA and LISA Detector Elements Logan Rice, Jonathan Wong The MoNA collaboration is a research group of students and faculty from 13 primarily undergraduate institutions, with detectors at the NSCL: MoNA (Modular Neutron Array) and the newly-built LISA (Large multi-Institutional Scintillating Array). These arrays each have 144 plastic scintillating bars. When a neutron collides with a hydrogen nucleus within the plastic, photomultiplier tubes at either end of the bar detect the scintillation photons. Their arrival times are used to determine the position of the event, but as the light travels through the detector it loses intensity exponentially. How dramatic this loss is can be described by a parameter called the attenuation length, with larger attenuation lengths corresponding to lower loss. Recently the MoNA collaboration conducted its LISA commissioning experiment investigating two-neutron decay states of $^{25}$O. As a part of LISA's commissioning, we measured the attenuation lengths of the individual detector bars that make up the LISA array and compared these lengths with those of the older MoNA array. We found that the LISA bars had a larger attenuation length on average with impacts on detector efficiency and effective threshold. [Preview Abstract] |
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EA.00113: $^{26}$Al Beam Production and its Application to Nuclear Astrophysics B. Richard, R. Tribble, L. Trache, G. Pizzone, B. Roeder Presumably produced during the supernova stage of stellar evolution, $^{26}$Al offers unique opportunities to better understand the processes of nucleosynthesis occurring in pre-SN phases of stellar evolution and within the Galactic disk. When decaying to $^{26}$Mg, $^{26}$Al emits a unique 1.8MeV gamma ray, detectable by satellite telescopes. Understanding the production and destruction pathways of $^{26}$Al is a key portion of understanding the on-going stellar nucleosynthesis. In order to measure the cross-section of $^{26}$Al(n, p)$^{26}$Mg at the astrophysical relevant energies, an indirect method, called the Trojan Horse Method(THM), is utilized. The THM allows the study of neutron induced reactions at astrophysical energies via the d break-up. This method requires the three-body cross section for the $^{26}$Al(d, p $^{26}$Mg)H reaction to be measured at a beam of 60 MeV. The $^{26}$Al secondary beam is produced by MARS at Cyclotron Institute of Texas A{\&}M University from a primary $^{26}$Mg beam (E$\approx $16MeV/u) impinging on a H$_{2 }$target, and was then degraded to 2.25MeV/u energy by means of a Be foil. The results will be shown and discussed in detail together with the features of the obtained intense and pure beam of $^{26}$Al (0.5cm x 0.5cm beamspot, $>$97{\%} pure, 10$^{6}$ pps). This later will be used for many applications in nuclear astrophysics using both direct and indirect methods. [Preview Abstract] |
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EA.00114: Slow Control System for the NIFFTE Collaboration TPC Erik Ringle As world energy concerns continue to dominate public policy in the 21st century, the need for cleaner and more efficient nuclear power is necessary. In order to effectively design and implement plans for generation IV nuclear reactors, more accurate fission cross-section measurements are necessary. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration, in an effort to meet this need, has constructed a Time Projection Chamber (TPC) which aims to reduce the uncertainty of the fission cross-section to less than 1{\%}. Using the Maximum Integration Data Acquisition System (MIDAS) framework, slow control measurements are integrated into a single interface to facilitate off-site monitoring. The Hart Scientific 1560 Black Stack will be used with two 2564 Thermistor Scanner Modules to monitor internal temperature of the TPC. A Prologix GPIB to Ethernet controller will be used to interface the hardware with MIDAS. This presentation will detail the design and implementation of the slow control system for the TPC. [Preview Abstract] |
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EA.00115: Locating a Radioactive High Voltage Nut for the M\textsc{ajorana} Project Benjamin Rose M\textsc{ajorana} is looking for a neutrinoless double beta decay in $^{76}$Ge. Due to the necessity of low background radiation in M\textsc{ajorana}, we wanted to see if one could locate a radioactively hot component, by analyzing GEANT4-generated Monte Carlo data. We used the data to determine the probabilities that a crystal will be hit given a source location. Our sources were the high voltage insulator nuts (HV nuts) spread through out the detector. We looked at their $ ^{224} $Ra decay series, especially the $ ^{208} $Tl peak with a region of interest (ROI) from $2.58-2.65 \, \mathrm{MeV}$. We studied the distribution of crystals that have events with energies in the ROI. We call this distribution the ``hit" distribution. We created randomly filled hit distributions based on the probabilities obtained from simulation and used the Kolmogorov-Smirnov test to compare the random fill to all the possible source distributions. The source distribution with the best KS value is used to determine the location of the source. The results show that with approximately 200 counts from a HV nut and no background you can resolve the source to the exact HV nut to with in $~90\%$ accuracy. With few events, we show that you can determine the region of the detector containing the HV nut to a 50\% accuracy. [Preview Abstract] |
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EA.00116: Simulations for Light Collection Efficiency (Jlab Hall C 12 GeV Kaon Aerogel Detector) Laura Rothgeb Studying the additional flavor degree of freedom in charged kaon production allows for an unexampled insight into the transition from hadronic to partonic degrees of freedom in exclusive processes and specifically the reaction mechanism underlying strangeness production. This unique opportunity has gone greatly unexplored, however, because of the challenges posed by the experimental factors. One of these challenges is determining a method of separation for kaons from pion and proton backgrounds at high momenta. The simplest and most cost-effective solution is the implementation of a kaon aerogel Cherenkov detector. At the Catholic University of America, we are building such a detector for use in the 12GeV Hall C Super High Momentum Spectrometer at Jefferson Lab. The detector will use photo multiplier tubes to collect the Cherenkov radiation given off by the aerogel and convert that signal into analyzable data that will be used to determine the form factor of the kaon, which will yield a greater understanding of the internal structure of the proton. In this presentation I will present the results from the simulations carried out to optimize the aerogel coverage and study the effect of light guides on the efficiency of the detector. [Preview Abstract] |
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EA.00117: Performance of Aerogels as Cherenkov Light Radiators Isaac Saldivar, David Blyth, Matt Gibson, Ricardo Alarcon Aerogels with indexes of refraction ranging approximately from 1.01 to 1.05 can fill an important need as high-yield Cherenkov light radiators and they are widely used by the scientific community, particularly in the experimental nuclear and particle physics arena. We have designed, constructed, and operated equipment to measure the Cerenkov light produced by the passage of relativistic charged particles through different aerogel samples. The samples come from Matsushita Electric Works (Japan) and Aspen Aerogels (USA). The measurements were conducted using a light-tight box, which housed the aerogel samples, two photomultiplier tubes (to measure Cherenkov radiation), and a pair of scintillators to count the number of particles through the aerogel. The photon yields from the samples have been analyzed and results will be presented in terms of the detected number of photoelectrons. [Preview Abstract] |
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EA.00118: Photon Beam Monitors at MAX-lab Christopher Seymour An important objective for nuclear scientists is to describe the properties of nucleons in terms of the framework provided by QCD. The various theoretical approaches can be tested by comparing the predictions from the theories with the results from accurate measurements. The Photon Tagging Facility at MAX-lab in Lund, Sweden is capable of tagging photons with energies up to 200 MeV, which is ideal for testing fundamental nuclear processes in the low-energy region. Exploring the pion photoproduction reaction near threshold will provide new high-quality data to compare with the predictions from various QCD-based theories. Careful monitoring of the photon beam characteristics is paramount to the success and accuracy of the experiment. Two beam monitoring systems are now in use with the tagged photon beam at MAX-lab. One system, the x-y Beam Monitor provides a way to detect horizontal or vertical shifts in the photon beam position. The second device, the In-Beam Monitor, is used to keep track of the photon flux and to monitor the tagging efficiency during the data acquisition. These measurements are crucial for the overall experiment. An overview of these two beam monitor systems, and their performance will be provided. [Preview Abstract] |
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EA.00119: Light Collection Efficiency in Thin Strip Plastic Scintillator for the Study of ISGMR in Unstable Nuclei Jacob Shafer The compressibility of nuclear matter (K$_{A})$ is one of the constituent of the equation of state for nuclear matter which is important in the study Neutron Stars and Super Novae. The K$_{A}$ is proportional to the Giant Monopole Resonance (GMR) energy and is related by the equation E$_{GMR}$=(h$^{2}$/mr$^{2})^{1/2}$ *(AK$_{A})^{1/2}$, where ``m'' is the mass of a nucleon and ``r'' is the radius of the nucleus. The GMR in unstable nuclei is important because the K$_{A}$ is related to the ratio of protons to neutrons. For this reason, it is desirable to study unstable nuclei as well as stable nuclei. The study of the GMR in unstable nuclei will be done using inverse kinematics on a target of Lithium ($^{6}$Li). A detector composed of two layers of thin strip scintillators and one layer of large block scintillators has been designed and constructed to give adequate energy and angular distribution over a large portion of the solid angle where decay particles from the ISGMR can be found. Attenuation of the light signal in the strip scintillators was measured using an Americium ($^{241}$Am) alpha source. Gains in light collection efficiency due to various wrapping techniques were also measured. The thin strip scintillators are connected to the photomultiplier tube (PMT) via bundles of optical fiber. Losses in light calculation efficiency due to fiber bundles were measured as well. [Preview Abstract] |
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EA.00120: M1 width of the $2^+_1$ state in $^{22}$Na and searches for tensor contributions to beta decays Devin Short, Alejandro Garcia, Smarajit Triambak, Steven Seininger, David Williams A determination of the $\beta$-$\gamma$ angular correlation from $^{22}$Na beta decay has been used to extract induced tensor current contributions to the weak interaction. The result, combined with other available data, yielded an unexpectedly large breaking of the Conservation of the Vector Current, a fundamental assumption of the Standard Model. A weak link in the data used for this analysis is the weak magnetism form factor, which is extracted from an independent unpublished determination of the analog isovector magnetic dipole ($2^+ \rightarrow 3^+$) $\gamma$-ray transition strength to the ground state of $^{22}$Na which was limited by low statistics. We have run an experiment seeking to improve on those results by using a $^{21}$Ne(p,$\gamma$) resonance at $E_p = 1112$ keV, leading to a $E_x = 7800 \rightarrow 1952 \rightarrow 0$ keV $\gamma$ cascade in $^{22}$Na. Angular correlation data were acquired using coincidence $\gamma$-rays in order to extract the M1-E2 mixing ratio. This, in conjunction with the 1952 keV branching ratio, will allow for a reliable determination of the M1 width. We are presently running Monte Carlo simulations that will help determine the absolute efficiency of our apparatus in order to extract the needed information. [Preview Abstract] |
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EA.00121: Dark Current in PHENIX Resistive Plate Chambers MariAnne Skolnik, Brett Fadem The PHENIX collaboration studies polarized proton collisions at the Relativistic Heavy Ion Collider (RHIC) in hopes of eventually understanding the source of angular momentum in the proton. In particular, the antiquark contribution to the ``spin'' can be ascertained via single spin asymmetries of muons that result from the decay of W bosons. Such muons typically have high momentum. A new subsystem in PHENIX consisting of resistive plate chambers (RPCs) enhances the muon trigger by allowing discrimination of high momentum muons and increases our chances of recording these rare events. In preparing the RPC modules, we conduct many quality assurance tests that require monitoring dark current in the modules. Analysis of this dark current will reveal its dependence on temperature, humidity, and gas gap geometry. [Preview Abstract] |
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EA.00122: Study of the crystal transparency changes of the CMS ECAL Caroline Sofiatti The Compact Muon Solenoid (CMS) is a general purpose detector installed at the Large Hadron Collider (LHC) at CERN, Geneva. Detection and precise energy measurement of photons and electrons is a key to new physics that is expected at the 100 GeV - TeV scale. Additionally, the discovery of the postulated Higgs boson is a primary goal at LHC and H $\rightarrow \gamma \gamma$ is the most promising discovery channel if the mass is between 114 and 130 GeV. In this mass range the Higgs decay width is very narrow, but the signal will lie above an irreducible background and so good energy resolution is crucial. A photon energy resolution of 0.5\% above 100 GeV has therefore been set as a requirement for the CMS performance. Light monitoring the transparency changes in the lead tungstate crystal plays a crucial role in maintaining the energy resolution for the CMS ECAL at LHC. This work presents the preliminary studies of the transient transparency changes of the crystals. Ultimately, this study will be used to implement an upgraded correction algorithm that will optimize the CMS discovery potential, particularly in the di-photon search channels. [Preview Abstract] |
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EA.00123: PHENIX Silicon Vertex Detector Software and Kalman Fitting Michael Stone, J. Nagle The PHENIX experiment at the Relativistic Heavy Ion Collider recently took data in p+p and Au+Au collisions with a new detector called the ``Silicon Vertex Detector.'' The main purpose of the detector is to measure heavy flavor meson decay electrons near the collision vertex and will thus allow for refined measurement of these processes, in particular the separation of charm and beauty contributions. Part of the work necessary to make this possible is the development of an offline software framework capable of reconstructing hit clusters, tracks, and as follows, entire events. This project covers the C++ objects and methods written to go from the raw data format, to clusters, and then to tracks. Specifically, the process of using Kalman fitting algorithms through a real magnetic field map for track reconstruction will be described. Initial tracking efficiency, momentum resolution, and computation speed will be detailed. [Preview Abstract] |
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EA.00124: Automating the Data Acquisition Process with Scripts Alexey Strakovsky, Baya Oussena This poster describes work done with the A2 Collaboration at the Johannes Gutenberg Universitaet (JGU) located in Mainz, Germany. The data acquisition system used by the A2 collaboration primarily gathers data from the Crystal Ball particle detector, Tagger Microscope, and the TAPS detector, all of which are housed at the Mainzer Mikrotron facility (MAMI) at JGU. There are many components to the software controlling the acquisition of data from these detectors, many of which are scripts. Currently, each script must be started manually and in a specific order by the system operator to perform a specific task or series of tasks. The purpose of this project is to reduce the dependency on the user to correctly run the necessary scripts, replacing the complex manual with a simple user interface, through which the user can give the system a procedure to carry out without worrying about most of the details of the procedure. When this project is completed, it will be much easier for system operators to effectively run the data acquisition system. [Preview Abstract] |
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EA.00125: Spin Assignments of excited states in $^{23}$Mg through a $^{24}$Mg(p,d)$^{23}$Mg reaction Sabrina Strauss, D.W. Bardayan, J.C. Blackmon, K.Y. Chae, K.A. Chipps, J.A. Cizewski, R. Hatarik, K.L. Jones, R.L. Kozub, J.F. Liang, C.D. Nesaraja, P.D. O'Malley, C. Matei, B.H. Moazen, S.D. Pain, S.T. Pittman, M.S. Smith The $^{22}$Na(p,$\gamma$)$^{23}$Mg reaction is part of the hot NeNa cycle, which is important for the nucleosynthesis of Ne and Na isotopes in stellar explosions such as novae. Observation of the characteristic $\gamma$-ray line at 1275 keV from the decay of $^{22}$Na is a promising mechanism to constrain nova models. As the reaction proceeds through resonances in $^{23}$Mg, the properties of $^{23}$Mg levels above the proton threshold are important. We measured the $^{24}$Mg(p,d)$^{23}$Mg reaction using 41 and 41.5 MeV proton beams and a 500 $\mu$g/cm$^{2}$ $^{24}$Mg target at the Holifield Radioactive Ion Beam Facility to better constrain the spins of important levels. Reaction deuterons were detected and identified in the segmented 16-strip silicon detector array SIDAR. By comparing the angular distributions and DWBA calculations, we are able to constrain the spins and parities of levels in $^{23}$Mg. Experimental details and a status report on the analysis will be presented. *This work is supported in part by the US DOE and the NSF. [Preview Abstract] |
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EA.00126: A Study of the Ionization of Deuterium Gas by Pyroelectric Crystals Bryce Taylor, Stephen Shafroth, Werner Tornow Pyroelectric crystals produce a stream of electrons or positive ions when heated or cooled in a near-vacuum environment. We studied the behavior of these crystals in deuterium gas. We look at what portion of the positive ion beam consists of $D_2^+ $ and what portion is $D^+.$ Since $D_2^+ $ contains only half the energy of $D^+$ per deuterium atom after traversing a given potential difference, it has a notably lower cross-section for fusing than $D^+$ does, which lowers neutron yield. Looking at the equivalent dissociation question for $H_2 $ gas, we find that $<$0.1{\%} is ionized as $H^+$ based on magnetic deflection of the ions. Analogous results are assumed for $D_2 .$ Furthermore, we present a new phenomenon in which groups of positive ions arrive at the detector at the same time similar to multiple peaks present in electron spectra reported by Brownridge and Shafroth.\footnote{J. D. Brownridge, S. M. Shafroth, D. Trott, B. Stoner, and W. Hooke, Appl. Phys. Lett. \textbf{78}, 1158 (2001)} We provide a new theory on the workings of pyroelectric crystals based on the expulsion of gas trapped inside the crystal to explain these findings and other results. Funding provided by grant DOE DE-FG52-09NA29465. [Preview Abstract] |
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EA.00127: Recent Augmentations of the Functionality of the Thermonuclear Reaction Rate Calculator (TReRaC) Kyle Thomsen, Michael Smith The chemical variety of our universe can be explained by stellar nucleosynthesis. Many thermonuclear reactions are studied by reproducing them in accelerator experiments and determining their rates. Using the codes available through the Computational Infrastructure for Nuclear Astrophysics (CINA), researchers can process the results of these experiments. One such program is the Thermonuclear Reaction Rate Calculator (TReRaC), which uses various experimental inputs including resonant energies, strengths, channel widths, and information on non-resonant contributions to calculate reaction rates. Presently, TReRaC is capable of quickly generating accurate rates which closely match those given in a number of publications. This adds to CINA capabilities by enabling a wider variety of nuclear information to generate rates. The next step in TReRaC's evolution is integration into the existing CINA complex so that it can be used by researchers worldwide. [Preview Abstract] |
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EA.00128: Ratio of Kaon and Pion valence-quark parton distributions Jeffrey Tibbals The $K^+$ and $\pi^+$ are composed of two valence quarks each, $u\bar{s}$ and $u\bar{d}$, respectively. The ratio of momentum fractions carried by the up valence quarks, $u_{K}/u_{\pi}$, has been measured by Badier et al. [1], and found to decrease with increasing Bjorken $x$. I extend the statistical model of Zhang et al. [2] to calculate the parton distribution functions for the $K^+$ meson and the $\pi^+$ meson. I consider the $\pi^+$ and $K^+$ as an infinite series expansion of quark-gluon Fock states. The probabilities of each state were calculated using detailed balance and the three processes $q \rightleftharpoons qg$, $g \rightleftharpoons q\bar{q}$ and $g \rightleftharpoons gg$. I find a sea asymmetry of $\bar{d}-\bar{u}\approx0.265$ in the $K^+$, but no sea asymmetry in the $\pi^+$. I used the RAMBO program to produce a Monte Carlo simulation for the momentum distributions of the n- parton Fock states of both $K^+$ and $\pi^+$, which determine the momentum distribution functions of the mesons. I compare the ratio of momentum fractions carried by the up valence quarks in each meson, $u_{K}/u_{\pi}$, to the experimental results, and to other theoretical calculations. \\[4pt] [1] J. Badier et al., Phys. Lett. B 93 (1980) 354.\\[0pt] [2] Y.-J. Zhang et al., Phys. Lett. B 523 (2001) 260. [Preview Abstract] |
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EA.00129: A Transverse Resonant Neutron Spin Flipper Justin Tomey A radio frequency spin flipper (RFSF) was designed to quickly and efficiently reverse the polarization of a neutron beam. Pulsing the RFSF on and off makes it possible to compare reactions with spin ``up'' neutrons versus spin ``down'' on a pulse-by-pulse basis to reduce systematic errors associated with drifts in beam current and detector efficiency. It will be used in an experiment to measure the parity violating neutron spin asymmetry in the reaction n+$^3$He = $^2$H+p with longitudinally polarized neutrons. The RFSF coil is designed with a double cos-theta pattern with current-carrying wire running down its length and end-caps. The transverse field allows for the manipulation of either transverse or longitudinal polarizations with almost 100\% polarization, since the neutron sees no fringe field. It is a resonant spin flipper, based on the principle of nuclear magnetic resonance (NMR). It creates an oscillating magnetic field at the exact Larmor frequency of the neutron. In the rotating frame of the neutron's spin, it views the transverse magnetic field as static and precesses at exactly the rate needed to reverse direction entirely upon exit of the spin flipper. [Preview Abstract] |
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EA.00130: Efficiency Studies of the Resistive Plate Chambers for PHENIX Trigger Upgrade Ramsey Towell The PHENIX experiment at RHIC studies polarized proton-proton collisions to learn more about the spin structure of the proton. PHENIX can only record a few thousand collisions of the millions that occur every second. A\textbf{ }trigger upgrade is required to select rare events. The trigger upgrade includes two sets of Resistive Plate Chambers (RPCs) that will be installed in both muon arms. The smaller RPCs will be installed closer to the collision point and will be constructed and installed before the next run. One of the many quality assurance tests that are performed on the RPCs is an efficiency measurement. In addition to the normal efficiency test that is ran on each module, some long-term tests are being performed to see how environmental factors (e.g. temperature, humidity, and pressure) cause a change in the performance of the chambers. This test is being performed on the chambers in a specially designed cosmic ray test stand using hodoscopes to trigger on cosmic muons that are tracked through the RPCs. These tests accumulate data for an extended period of time while the environmental conditions are continuously monitored. The results from these tests will be presented. [Preview Abstract] |
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EA.00131: Optimization and Expansion of the Qweak Database Grace Trees, Damon Spayde Weak interactions have been found to violate parity conservation and can be observed in electron-proton scattering. The results of the scattering reveal an asymmetry in the scattering-rate of electrons in the detectors as the helicity of the beam is flopped. By measuring this asymmetry, the Qweak experiment can determine weak charge of the proton. That value can then be used to calculate the weak mixing angle. The weak mixing angle can indicate if there is physics beyond the Standard Model. The experiment will be collecting data for approximately 2200 hours at the Thomas Jefferson Lab National Accelerator Facility. A database has been implemented to allow for storage and organization of the collected data so it can be analyzed at a future time. This database must be optimized in order to allow quick and easy access for every member of the collaboration. This optimization can be accomplished through speed tests to weigh different techniques that can be used in the database as well as altering and expanding the database for improved data procurement. [Preview Abstract] |
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EA.00132: Development of Water Target for Radioisotope Production Nathan Tripp Ongoing studies of plant physiology at TUNL require a supply of nitrogen-13 for use as a radiotracer. Production of nitrogen-13 using a water target and a proton beam follows the nuclear reaction 16-O(p,a)13-N. Unfortunately the irradiation of trace amounts of oxygen-18 within a natural water target produces fluorine-18 by the reaction 18-O(p, n)18-F. The presence of this second radioisotope reduces the efficacy of nitrogen-13 as a radiotracer. Designing a natural water target for nitrogen-13 production at TUNL required the design of several new systems to address the problems inherent in nitrogen-13 production. A heat exchanger cools the target water after irradiation within the target cell. The resulting improved thermal regulation of the target water prevents the system from overheating and minimizes the effect of the cavitations occurring within the target. Alumina pellets within a scrubbing unit remove the fluorine-18 contamination from the irradiated water. The modular design of the water target apparatus makes the system highly adaptable, allowing for easy reuse and adaptation of the different components into future projects. The newly designed and constructed water target should meet the current and future needs of TUNL researchers in the production of nitrogen-13. [Preview Abstract] |
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EA.00133: Construction and Commissioning of a New Scattering Chamber at the Union College Ion Beam Analysis Laboratory Colin Turley, Robert Moore, Christopher Johnson, Maria Battaglia, Michael Vineyard, Scott LaBrake We have constructed a new scattering chamber in the Union College Ion Beam Analysis Laboratory to improve our experimental capabilities. The new chamber was constructed from a ten-inch, conflat, multi-way cross. We fitted the chamber with an eight-inch, Leybold turbomolecular pump so that it can be evacuated quickly. A target manipulator with stepper motors that provide x, y, and z-positioning of the target with micron precision is mounted atop the chamber. A target ladder was constructed for the manipulator that allows us to analyze multiple samples without breaking the vacuum. The chamber has a door with an O-ring seal mounted on one of the ten-inch ports that provides easy access to the interior of the chamber. An Amptek silicon-drift X-ray detector is mounted close to the target ladder, inside the vacuum so that low-energy X-rays can be detected. A new Faraday cup was also installed to provide more accurate current measurements. Finally, a new collimator system was developed and installed in the beam-line to the scattering chamber to provide a well-defined beam spot. A proton induced X-ray emission analysis of aerosol samples has been performed as the commissioning experiment for the chamber. Here, we report on the construction and commissioning of this new chamber. [Preview Abstract] |
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EA.00134: Fast beam optics simulation of low-energy beam transport systems with a matrix method Adrian Valverde, Georg Bollen, Ryan Ringle The Low Energy Beam and Ion Trap (LEBIT) facility at the NSCL utilizes thermalized rare isotope beams produced via projectile fragmentation for high-precision Penning trap mass measurements. Ions are transported between the different components using an electrostatic ion optical system. Optimizing ion transport can be difficult as the parameter space is large and it is not immediately obvious what effect changing a parameter has on the beam. SIMION is a program that provides a very accurate way to model the paths of these ions; however, it can take considerable time, so to quickly calculate the effect of minor adjustments to the potentials, a different method is desirable. Matrix ion optics provides such a method; like in matrix optics for light, matrices are created to model the focusing effect of the elements in the system. A specific method for the modeling of certain electrostatic elements can be found in papers by G.H. Gillespie and T.A. Brown. The purpose of this project was to create an implementation of the matrix methods for einzel lenses and acceleration columns in python, and test the results from the program against those produced by SIMION. Thus far, the comparison between SIMION values and those calculated through this method have shown good agreement; as it provides a good approximation of the actual path, it can be used to predict the path of the beam. [Preview Abstract] |
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EA.00135: Testing and Installation of a High Efficiency CsI Scintillator Array Natalie Viscariello, Stuart Casarotto, Nathan Frank, Jenna Smith, Michael Thoennessen Experiments on neutron-rich nuclei have identified changes to the structure of nuclei far from stability. The Sweeper-MoNA- LISA facility at the National Superconducting Cyclotron Laboratory (NSCL), located at Michigan State University, is used for performing experiments on neutron-rich nuclei. Currently, these experiments are limited to the mass region below neon due to the resolution of the charged fragment detectors, which limit the isotope separation. The resolution of the system will be improved with changes to the setup, primarily due to a new scintillator array. The new array will consist of twenty-five sodium-doped CsI crystals arranged in a 5 x 5 configuration. The array will be used to measure the kinetic energy of charged fragments with energies in the GeV range. The improved resolution will allow experiments of unbound systems above neon. The testing and assembly of the detector array will be presented. [Preview Abstract] |
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EA.00136: GEANT4 Implementation of Calorimeters for a Medium-energy Electron Ion Collider James Walker Detector designs for an Electron-Ion Collider (EIC) require detection of the scattered lepton and hadronic debris with high precision as well as all the particles involved in the reaction. GEANT4 simulations will be used in order to optimize the Medium-energy EIC (MEIC) detector design to these requirements. Before simulating detector efficiencies, hadronic and electromagnetic calorimeter models must be incorporated into a full detector geometry. Electromagnetic calorimeter models were constructed as a mixture of lead tungsten and lead glass. Hadronic calorimeter models are still in design. The models are at a low stage of complexity currently, but can be developed further. The models can be used in further research to maximize efficiencies of detector designs and minimize cost. [Preview Abstract] |
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EA.00137: Photonuclear Production of Medical Isotopes Nick Weinandt Every year, more than 20 million people in the United States receive a nuclear medicine procedure. Many of the isotopes needed for these procedures are under-produced. Suppliers of the isotopes are usually located outside the United States, which presents a problem when the desired isotopes have short half-lives. Linear accelerators were investigated as a possible method of meeting isotope demand. Linear accelerators are cheaper, safer, and have lower decommissioning costs compared to nuclear reactors. By using ($\gamma $,p) reactions, the desired isotope can be separated from the target material due to the different chemical nature of each isotope. Isotopes investigated were Cu-67, In-111, and Lu-111. Using the results the photon flux Monte Carlo simulations, the expected activity of isotopes can be calculated. After samples were irradiated, a high purity germanium detector and signal processing apparatus were used to count the samples. The activity at the time of irradiation stop was then calculated. The uses of medical isotopes will also be presented. [Preview Abstract] |
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EA.00138: Targets for Inverse ($^3$He,d) Reaction Studies with Radioactive Ion Beams J.L. Wheeler, R.L. Kozub, S.A. Graves, D.J. Sissom, D.W. Stracener, D.W. Bardayan, C. Jost, P.D. O'Malley Proton transfer reactions, such as ($^3$He,d), are extremely important for measuring the properties of single particle states and resonances. Many such resonances are important in the rp process of explosive nucleosynthesis, but cannot be measured via resonance scattering directly. For the ($^3$He,d) reaction, it is necessary to use localized $^3$He targets, and gas jet targets are expensive and difficult to construct. We are continuing\footnote{D.J. Sissom et al., http://meetings.aps.org/link/BAPS.2008.DNP.DA.92}$^,$\footnote{J.L. Wheeler et al., http://meetings.aps.org/Meeting/DNP10/Event/132092} an alternate approach - implanting $^3$He into 0.65 $\mu$m thick aluminum foils at the On-Line Test Facility (OLTF) at ORNL. Target profiles are analyzed using Rutherford backscattering to determine the concentration and distribution of the implanted $^3$He. An update of these results and a detailed description of new procedures will be presented. This research is supported by the U. S. Department of Energy. [Preview Abstract] |
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EA.00139: Simulations of the In-Beam Performance of the CAESAR and Gretina Arrays With Liquid-Hydrogen and Solid Targets Samantha Wildonger In order to plan gamma-ray spectroscopy experiments at the National Superconducting Cyclotron Laboratory (NSCL), we used Geant4 simulations of the CAESAR and Gretina arrays with the Ursinus College Liquid Hydrogen Target and a solid 9Be target. Analysis of the simulated data allows us to evaluate the precision of measured gamma-ray intensities, photopeak efficiencies, and the in-beam energy resolution of each array. The relative advantages of each array will be discussed. [Preview Abstract] |
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EA.00140: Optimization of MCMC algorithm for the calculation of interaction and reaction cross sections in the Glauber Theory framework John Wilson, Ivan Novikov To extract various parameters of a nuclear density distribution, the experimentally measured interaction cross-section is compared to cross-sections calculated in various theoretical approaches. The calculation of the interaction and reaction cross-section in the Glauber Theory framework are usually performed using a Monte Carlo technique. In the presented paper, we discuss the accuracy of the Markov Chain Monte Carlo (MCMC) approach to calculating the interaction and reaction cross-sections. Using various statistical diagnostics, we evaluate the ``quality'' of the random numbers generated by the Metropolis-Hastings algorithm which are utilized to calculate the cross-sections. The dependence of the accuracy of the determined nuclear density parameters on the ``quality'' of the Markov chains was obtained for the Woods-Saxon density distribution and the harmonic oscillator (OH) density distribution. [Preview Abstract] |
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EA.00141: Characterization of aerogel and Photomultiplier Tubes for the 12-GeV Hall C Kaon Aerogel Detector at Jefferson Lab Kevin Wood Thomas Jefferson National Accelerator Facility's upgrade from 6-GeV to 12-GeV beam energy requires a new magnetic spectrometer for Hall C. At 6 GeV the High Momentum Spectrometer (HMS) made use of an aerogel threshold Cherenkov detector for particle identification of p/K/p. The HMS is not designed to operate at momenta greater than 7 GeV/c, instead a Super High Momentum Spectrometer (SHMS) will be constructed. An aerogel threshold Cherenkov detector needs to be included in the new spectrometer as well. Pions, kaons and protons of sufficient velocity produce Cherenkov radiation when passing through media with low indices of refraction. Aerogels with n = 1.020 and n = 1.030 will be used for p/K/p separation. A diffusion box, lined with millipore, will collect the light from the Cherenkov radiation. Photomultiplier tubes (PMTs) will then detect the light and convert the photons into an electrical signal that electronics will then be able to interpret. This presentation will show the dependence of the aerogel's signal strength on thickness of stack as well as the PMTs' gain dependence on high voltage. [Preview Abstract] |
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EA.00142: Study of Rescattering Effects in }$\vec {\gamma }d\to K^+\Lambda n$\textbf{ through Helicity Asymmetries Weizhi Xiong Here we present our experimental study of rescattering effects in the reaction $\vec {\gamma }d\to K^+\Lambda n$ through beam-helicity asymmetries. The nuclear reaction was initiated by circularly polarized photon beam on unpolarized liquid deuterium target. The data were collected with the CLAS detector at Jefferson Lab. The goal of this project is to identify kinematics at which final-state interactions are maximal. Our investigation is part of a larger program carried out at USC studying the hyperon-nucleon interaction through rescattering between the lambda ($\Lambda )$ and the neutron in the deuteron. In order to determine beam-helicity asymmetries, we construct and study $\varphi $ (azimuthal angle)-dependent asymmetry distributions. Since for the elementary process $\vec {\gamma }p\to K^+\Lambda$ the helicity asymmetry is zero, large asymmetries would indicate large rescattering effects in the final state. In this presentation we will show how we identify the outgoing particles and the reaction of interest, and will give very preliminary estimates for the beam-helicity asymmetry for various choices of polar and azimuthal angles. [Preview Abstract] |
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EA.00143: Noise studies on the PHENIX RPC1 prototype Emily Zarndt An important goal of the PHENIX collaboration at the Relativistic Heavy Ion Collider is to measure the spin contributions of sea quarks to the overall spin of the proton. The detection of W-bosons resulting from polarized p-p collisions enables us to directly probe and separate by flavor the spin dependent quark and anti-quark distributions in the proton. In order to improve the trigger efficiency for final state muons with high transverse momentum from W-boson decay, the muon spectrometers in PHENIX are being upgraded with fast front-end electronics for the cathode strip tracking chambers and with two stations of Resistive Plate Chambers (RPCs). A prototype of RPC1, the RPC station near the collision point upstream of the muon tracking magnet, was tested in a cosmic ray test stand including detailed studies of the signal noise: we have carried out an optimization of the threshold used in the RPC pre-amplifier, characterized the noise for different high voltage settings and front-end shielding configurations, and measured the average noise rates. These studies have led to the final techniques used for the RPC1 detector assembly and to the choice of operating parameters for the detector. [Preview Abstract] |
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EA.00144: Radiation Hardness of Trigger Electronics Irene Zawisza, Alexei Safonov, Jason Gilmore, Vadim Khotilovich As the maximum intensity of particle accelerators increases, probing the most basic questions of the Universe, detectors and electronics must be designed to insure reliability in high-radiation environments. As the Large Hadron Collider (LHC) beam intensity is increased, it is necessary to upgrade the electronics in the Compact Muon Solenoid (CMS). To select interesting events, CMS utilizes fast electronics, which are installed in the experimental cavern. However, much higher post-upgrade levels of radiation in the cavern set tight requirements on the radiation hardness of the new electronics. Damaging effects of high and low energy radiation leads to disruption of digital circuits and accumulated degradation of silicon components. Quantifying the radiation exposure is required for the design of a radiation-tolerant system, but current simulation studies suffer from large uncertainties. We compare simulation predictions with measured performance in two different experimental studies, which evaluate component performance for pre and post irradiation determining the survivability of electronics in the harsh CMS environment. [Preview Abstract] |
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