Bulletin of the American Physical Society
3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009; Waikoloa, Hawaii
Session GB: Conference Experience for Undergraduates Poster Session (1:00-3:00 PM) |
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Chair: Warren Rogers, Westmont College Room: Grand Promenade |
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GB.00001: Rate Capability of Doped Linseed Oil coated Bakelite RPCs Zarah Ahmad Bakelite Resistive Plate Chambers (RPCs) are used as muon trigger detectors for the PHENIX experiment at RHIC and the CMS and ATLAS experiments at LHC. These muon trigger RPCs are gas detectors in which high voltage is applied across two Bakelite plates spaced 2 mm apart. The detector gas is 95{\%} R134-a, 4.5{\%} isobutene and 0.5 {\%} SF6 The rate capability of Bakelite RPCs is limited by the time it takes to re-store the initial charge distribution on the dielectric plates after the ionization charge from an avalanche has been collected on the plates. The rate capability depends on the bulk and surface resistivity of the Bakelite plates and its coating. We have doped the linseed oil coating used in the PHENIX RPCs to lower the surface resistivity of the coated Bakelite plate. The rate capability of the modified RPCs was studied using measurements of the RPC detection efficiencies for cosmic rays in presence of high rate backgrounds from two Fe55 radioactive sources. We will present methods for the production of doped linseed oil coats and discuss status and results from rate capability measurements. [Preview Abstract] |
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GB.00002: The production and Testing of High Voltage Cables for Resistive Plate Chambers in the PHENIX Detector Ethan Allen The Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) is located on the Relativistic Heavy Ion Collider (RHIC) ring at Brookhaven National Laboratory. One of the primary goals of PHENIX is to study the spin structure of the proton. The creation of a fast muon trigger will allow scientists to measure high momentum muons at forward rapidity to sample the rare leptons from W decay at the highest luminosities. To achieve this, Resistive Plate Chambers (RPCs) and new front-end electronics will be installed to select the high P$_{T}$ muons from the low P$_{T}$ muon background. This upgrade will enhance our ability to collect and analyze muons that decay from W-bosons produced in polarized proton-proton collisions at $\surd $s = 500 GeV. This poster will focus on the production and testing of high voltage cables for RPC modules. The HV cables are used to distribute high voltage to create a potential difference between two resistive plates in order to amplify the ionization electrons after a charged particle passes through the gaps. The RPCs require 10 kV for efficient operation, which is much higher than in most applications. Over 200 cables are required to complete this upgrade. [Preview Abstract] |
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GB.00003: The ALICE Electromagnetic Calorimeter: Assembly and Test Beam Analysis Jessamyn Allen, Federico Ronchetti, Delia Hasch The electromagnetic calorimeter (EMCal) is under installation in ALICE at the LHC. The detector will enhance ALICE's jet-quenching measurement capabilities. Electrons and photons deposit their energy by interacting with the detector's lead and scintillator layers, via bremsstrahlung radiation, pair production and ionization, initiating an electromagnetic shower. Scintillator emissions are collected by wavelength-shifting fibers that transmit the light to a photodiode and subsequent electronics. Module assembly continues at the Laboratori Nazionali di Frascati and other sites. In addition to assembly, calibration tests and analysis are ongoing to investigate the detector's position resolution, the linearity of the detector's response and particle identification capabilities. Hadron and electron beams were used at CERN's PS and SPS facilities. From these test runs, one can calculate the detector's hadron rejection factor, which is a measure of the EMCal's ability to discriminate between particles of different types. Data from the test beam runs can also be used to improve simulations modeling the detector. [Preview Abstract] |
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GB.00004: Discovery of Cadmium, Indium, and Tin Isotopes Stephanie Amos, Michael Thoennessen As of today, no comprehensive study has been made covering the initial observations and identifications of isotopes. A project has been undertaken at MSU to document the discovery of all the known isotopes. The criteria defining discovery of a given isotope is the publication of clear mass and element assignment in a refereed journal. Prior to the current work the documentation of the discovery of eleven elements had been completed$^{1}$. These elements are cerium$^{2}$, arsenic, gold, tungsten, krypton, silver, vanadium, einsteinium, iron, barium, and cobalt. We will present the new documentation for the cadmium, indium, and tin isotopes. Thirty-seven cadmium isotopes, thirty-eight indium isotopes, and thirty-eight tin isotopes have been discovered so far. The description for each discovered isotope includes the year of discovery, the article published on the discovery, the article's author, the method of production, the method of identification, and any previous information concerning the isotope discovery. A summary and overview of all $\sim $500 isotopes documented so far as a function of discovery year, method and place will also be presented. $^{1}$http://www.nscl.msu.edu/$\sim $thoennes/2009/discovery.htm $^{2}$J.Q. Ginepro, J. Snyder, and M. Thoennessen, At. Data Nucl. Data. Tables, in press (2009), doi:10.1016/j.adt.2009.06.002 [Preview Abstract] |
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GB.00005: Search for the single-$\beta$ decay of $^{48}$Ca Hiroki Ando, Kazuya Takubo Large efforts have been made to search for the single-$\beta$ decay of $^{48}$Ca, for the purpose of determining its lifetime. At present we have the experimental lower limit of the lifetime; it is T$_{1/2}>$6.0x10$^{18}$yr as the most stringent value, but is still much shorter than the theoretical estimate of T$_{1/2}$=7.6x10$^{20}$yr. We aim to satisfy the followings (1)$\sim$(3) in final phase of our experiment. (1) Enrichment of $^{48}$Sc which is a daughter nucleus of $^{48}$Ca. (2) To achieve the highest coincidence efficiency, we will use large detectors with optimum layout. (3) Background reduction by using appropriate shields and underground laboratory. We are preparing the first phase of our experiment where we will find the optimal layout of detectors and shields. We will then go to the enrichment. Presently we are searching for the optimum layout with GEANT4 simulation, considering rough experimental setup. We will use 6 NaI(Tl) detectors which is size of 5x5x21cm$^{3}$. We put these detectors close to each other to achieve 4$\pi$-detector by which 1160cm$^{3}$ of Ca sample can be fully covered. Then about 1000g CaCO$_{3}$ powder(density is roughly 1g/cm$^{3})$ can be put in this space. We will report the preliminary result of the first phase of our experiment and future plan. [Preview Abstract] |
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GB.00006: Archiving Quality Control Tests in the PHENIX Resistive Plate Chamber Assembly Facility Keller Andrews The PHENIX collaboration at RHIC studies polarized proton-proton collisions to better understand the spin structure of the proton. PHENIX is in the process of upgrading the muon trigger to improve our capabilities of selecting the muons from the decay of W-bosons which are produced more readily at a high transverse momentum than other muon sources. By triggering on single, high transverse momentum muons, new observations on the spin asymmetries of a proton can be obtained. The trigger upgrade will consist of four stations of Resistive Plate Chambers (RPCs), with stations on each side of the interaction region. Each RPC consists of two Bakelite gas gaps, a copper signal plane, an aluminum case, and several layers of mylar and copper. With all of these parts comes the need to archive the manufacturing and quality assurance information along with test results performed on them. This information is kept in a Postgresql Database in the RPC factory and is maintained, modified, and read out through several PHP web pages. A new output page has been produced that will make all of this information much more accessible. This poster will focus on what data is archived, how it is stored, and how it can be easily retrieved and put to use. [Preview Abstract] |
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GB.00007: Sarcophagus of the CMS Zero Degree Calorimeters Kyle Axton, Michael Murray The Zero Degree Calorimeters of the CMS experiment at the Large Hadron Collidor will become significantly radioactive after the first few proton-proton runs. The detectors sit within large copper blocks, called TANS, that also include the two beam pipes. The calorimeters must be removed during bake out of the beam pipes. To minimize the radiation received by the personal a remotely controlled crane will place the calorimeters into a sarcophagus that will shield workers from the induced radioactivity. Both the mass and size of the sarcophagus are limited by constraints of the LHC tunnel. We will describe the design, construction and use of the sarcophagus. [Preview Abstract] |
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GB.00008: Nuclear Structure of $^{101}$Pd N.S. Badger, D.A. Meyer, A. Heinz, R.J. Caperson, B. Huber, J.D. LeBlanc, R. Luttke, E.A. McCutchan, J. Qian, B. Shoraka, J.K. Smith, J.R. Terry, H. Ai, J.L. Hugon, E. Williams $^{101}$Pd lies in a region of nuclei where A$\approx $110 and structural changes from vibrational to rotational are significant. In order to examine the nuclear structure of $^{101}$Pd, an experiment was performed at the Wright Nuclear Structure Laboratory at Yale University using the ESTU-1 Tandem Van de Graaff Accelerator. A beam of 70 MeV $^{12}$C collided with $^{92}$Zr target nuclei to produce $^{101}$Pd via the $^{12}$C + $^{92}$Zr $\to \quad ^{101}$Pd + 3$n$ reaction. Emitted $\gamma $-rays were detected by the SPEEDY array consisting of eight Compton-suppressed HPGe clover detectors. Then, $\gamma -\gamma $ coincidence measurements were made using RadWare to analyze the data. We were able to confirm many energy levels and observe several new ones. Also, new inter-band connections have been discovered. The structure of $^{101}$Pd was then interpreted using the strictly empirical E-GOS (E-Gamma Over Spin) method. The E-GOS plot, created by graphing energies of $\gamma $-rays over spin versus spin, revealed a clear transition from vibrational structure to rotational structure. [Preview Abstract] |
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GB.00009: Deconvolution of Bremmstrahlung Spectra from Measurements T.A. Balint, G.P. Trees, B.A. Detwiler, J.J. Carroll The X-ray Effects Laboratory (XEL) at Youngstown State University primarily uses an industrial X-ray bremmstrahlung source for in-house experimentation. This source has a high photon flux, with energies emitted in a non-uniform but smooth and continuous spectrum over a range that can reach a maximum of 450 keV. To quantitatively analyze the results of any irradiation producing nuclear photoactivation, it is necessary to first accurately determine this bremsstrahlung spectrum. This poster explores measurements of the response function for a shielded HPGe detector and how that function is used to determine the actual bremsstrahlung spectrum incident on the detector by a numerical deconvolution. [Preview Abstract] |
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GB.00010: Partitional Clustering Algorithms for Prompt-Photon Identification in the STAR Endcap Electromagnetic Calorimeter Benjamin Barber, Jason Webb Photon candidates are frequently identified in electromagnetic calorimeters utilizing hierarchical algorithms, whereby detector elements are clustered based upon a fixed set of clustering criteria, which a candidate cluster must satisfy to be considered. Imperfections in detector response and event-to-event fluctuations result in the rejection of true candidates. When searching for rare signals, such as prompt-photon production in pp collisions, such inefficiencies are undesirable. Partitional clustering is an alternative approach. Partitional clustering divides detector elements between a preset number of clusters based upon their distance to the cluster centers, and iterates until the position of the cluster centers converges. This approach is advantageous when $N_{clusters}$ is known. This research applies partitional clustering to the problem of $\pi ^{0}$/$\gamma $ discrimination in the STAR Endcap Electromagnetic Calorimeter (EEMC). The EEMC is a lead-scintillator sampling calorimeter, with a highly-segmented scintillator strip shower maximum detector (SMD). Partitional clustering algorithms, with $N_{clusters}$ = 2, are applied to the SMD strips corresponding to large energy deposits in the EEMC. The clusters are used to calculate two-body decay kinematics. In simulation, invariant mass distributions show a good separation between prompt photons and $\pi ^{0}$ background. [Preview Abstract] |
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GB.00011: Neutron Capture Rates and the r-Process Abundance Pattern in Shocked Neutrino-Driven Winds Daniel Barringer, Rebecca Surman The r-process is an important process in nucleosynthesis in which nuclei will undergo rapid neutron captures. Models of the r-process require nuclear data such as neutron capture rates for thousands of individual nuclei, many of which lie far from stability. Among the potential sites for the r-process, and the one that we investigate, is the shocked neutrino-driven wind in core-collapse supernovae. Here we examine the importance of the neutron capture rates of specific, individual nuclei in the second r-process abundance peak occurring at A $\sim $ 130 for a range of parameterized neutrino-driven wind trajectories. Of specific interest are the nuclei whose capture rates affect the abundances of nuclei outside of the A $\sim$ 130 peak. We found that increasing the neutron capture rate for a number of nuclei including $^{135}$In, $^{132}$Sn, $^{133}$Sb, $^{137}$Sb, and $^{136}$Te can produce changes in the resulting abundance pattern of up to 13{\%}. [Preview Abstract] |
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GB.00012: Calibrating the PHENIX Muon Piston Calorimeter for the Analysis of Au+Au Collisions Jonathan Ben-Benjamin The Pioneering High Energy Nuclear Interaction eXperiment (PHENIX), located at the Relativistic Heavy Ion Collider (RHIC) ring at Brookhaven National Laboratory, is designed to examine direct probes from proton-proton and heavy ion collisions. The PHENIX Muon Piston Calorimeter (MPC) is being calibrated for a measurement of transverse energy in the forward region, 3.1$<|\eta|<$3.8, using RHIC Au+Au collisions at $sqrt{s_{NN}}$ = 200 GeV. The MPC consists of 196 towers in the north station and 220 towers in the south. The gain of each tower will be calibrated using an iterative process based on the $\pi^{0}$ peak formed from the photon pairs into which they decay. This poster will focus on the methods we use for the reconstruction of $\pi^{0}$, such as data cuts, background generation and data isolation. [Preview Abstract] |
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GB.00013: Unifying Inflation and Dark Energy Using an Interacting Holographic Model Abby Besemer, Michael Berger The universe has gone through at least two very different periods of accelerated expansion. The earliest stage was a rapid exponential expansion known as inflation while the acceleration we are experiencing at the current epoch is driven by dark energy. Because the energy scale of dark energy is approximately 27 orders of magnitude smaller than that of inflation, the relationship between the two periods of acceleration is unknown. The introduction of an interaction between dark energy and matter and the holographic principle offers a possible way to unify these two eras of expansion using a model based on a simple physical principle. Here we present a possible expansion history for the universe using a model of interacting holographic dark energy. [Preview Abstract] |
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GB.00014: Investigation of Structure of Gd and Tb Nuclei using STARS and LiBerACE Cain Bonniwell, Ben Pauerstein, J.M. Allmond, C.W. Beausang This experiment, performed at Livermore Berkeley National Lab as a collaboration of Livermore, Berkeley, and the University of Richmond, was designed to investigate the structure of gadolinium and terbium nuclei using the P + 156Gd reaction at E beam = 27 MeV. The experimental design included use of the STARS system for detecting charged particles as well as the LiBerACE clover array for detecting gamma rays. The master gate was set to record particle-gamma as well as gamma-gamma coincidences. The data is currently being analyzed using the RADWARE escl8r software package which has allowed the creation of extensive level schemes for several Gd and Tb nuclei. So far the data suggests new gamma ray transitions as well as new energy states in 154Gd and 155Tb. The project is ongoing, and the results will be presented. This work was supported by the US Department of Energy under grant numbers DE-FG52NA26206 and DE-FG02-05ER41379. [Preview Abstract] |
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GB.00015: Optimizing the Fermilab E-906 Spectrometer Design Using GEANT Simulations Brandon Bowen Experiment 906 at Fermi National Accelerator Laboratory (FNAL) is a fixed target experiment measuring Drell-Yan scattering. The purpose of E-906 is to determine the ratio of anti-down to anti-up quarks in the nucleon sea by measuring the total cross section of the Drell-Yan muon pairs from liquid hydrogen and liquid deuterium targets. E-906 will extend the FNAL E- 866/NuSea measurements to higher Bjorken x, which will help reveal the structure of the proton. These results focus on using GEANT4 Monte Carlo simulations to investigate spectrometer acceptance and background rates at the downstream end of the spectrometer using various amounts and types of absorbers. Muons in the simulations were generated over a momentum range of 15 to 35 GeV for each proposed configuration, since at this location the background will be dominated by electrons knocked out of the shielding blocks by muons. These simulations will determine the downstream shielding that will be used in the experiment. [Preview Abstract] |
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GB.00016: Monte Carlo Fast Dose Calculator for Proton Radiotherapy Travis Brannan, Jessie Huang, Pablo Yepes Monte Carlo methods used in proton radiotherapy are more accurate than commonly used analytical dose calculations, at the cost of being computationally intense. We intend to show the feasibility of the Fast Dose Calculator (FDC), a Monte Carlo track-repeating algorithm based on GEANT4, to perform dose calculations for a clinical proton beam. FDC was developed to retain the accuracy of the Monte Carlo approach while substantially decreasing the calculation time required. FDC uses a database of proton trajectories in water and extrapolates this data in order to calculate the dose in heterogeneous media by scaling the proton range and scattering angles. FDC has been extended to include all of the patient-dependent elements of a passive proton scattering treatment unit: aperture, range compensator, and voxelized patient geometry. Improved database packing provides additional computational efficiency in FDC, which speeds calculation by more than two orders of magnitude. In addition FDC shows no dependence on calculation times with the number of voxels, unlike GEANT4. The dosimetric accuracy of the FDC algorithm was validated by comparing the results with GEANT4. [Preview Abstract] |
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GB.00017: Sensitivity to masses in the r-process Sam Brett, Ani Aprahamian The rapid neutron capture process is thought to produce over 50\% of the elements beyond iron and still remains, in many ways, a mystery. Questions about the site, conditions and whether it is a single process are outstanding open questions. The process is affected by the astrophysics of the scenario and the nuclear physics of the nuclei involved in the process. Simulations of the r-process require large sets of data such as cross sections, separation energies and decay rates. Clearly, it would be desirable if all of these data sets to be observed and experimentally proven, but since we are looking toward extremely neutron rich nuclei, perilously close to the drip line, we must use many theoretical values. Using an r-process simulation written by Bradley Meyer in 1993, we have been able to see the effects of changing the mass models (and therefore the separation energies) on the final abundances. The input includes the Finite Range Droplet Model, the ETFSI, Duflo-Zucker, and F0 models. By comparing these theoretical models against each other and against known masses, we hope to be able to suggest key regions for further mass measurements. [Preview Abstract] |
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GB.00018: Determination of Neutron Branching in $^{12}$C+$^{12}$C Fusion Justin Browne The neutron branch of the $^{12}$C+$^{12}$C is important for the carbon shell burning and carbon explosive burning. The $^{23}$Mg created by the $^{12}$C($^{12}$C,n)$^{23}$Mg reaction may undergo $\beta^+$ decay, changing the neutron excess in the combusting material, and the neutrons emitted from this reaction may contribute to s- and r-processes. Both the $\beta^+$ decay and the neutron emission greatly affect the subsequent nucleosynthesis in the star. A detection system, consisting of an array of four plastic scintillators and two Germanium detectors, has been developed to detect the decay of the $^{23}$Mg. The system has been tested at $E_{c.m.}=4.24$MeV. Using $\beta^+ - \gamma$ coincidence technique, the $^{23}$Mg reaction products has been unambiguously identified. [Preview Abstract] |
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GB.00019: The Muon Tracker Front End Electronics for the PHENIX Muon Trigger Upgrade David Broxmeyer The RHIC spin program at Brookhaven National Laboratory is designed to determine the spin of the constituents of the nucleon by using the collision of polarized protons. An elegant technique for determining the angular momentum of different flavors of quarks and anti-quarks is to use the parity violating decay of W bosons into high transverse momentum muons. PHENIX is engaged in an upgrade to its muon trigger to help select events that contain these high transverse momentum muons. This upgrade consists of four new stations of Resistive Plate Chambers (RPCs) and an upgrade to the front end electronics of the existing muon tracking system. A portion of the signal from the muon tracker will now be split off for use in the new trigger. The current electronics allow excellent position resolution in the offline analysis, but not very good timing resolution for the trigger. The front end electronics that are fed by the split signal will allow a rough determination of position and excellent timing information. The status of the RPC installation and new front end electronics will be described. [Preview Abstract] |
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GB.00020: Nuclear Structure in Even-Even Nuclei, $24\le Z\le 72$ Sarah Buchhorn Analysis of the spectra of excited nuclei has been used for decades to reveal trends and build models. Power regressions of the form $E(J)=a(\sqrt {J(J+1)} )^b$ fitted to the \textit{yrast} line of isotopes reveal an average $b$ of $_{\sim }\raise0.5ex\hbox{$\scriptstyle 4$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 3$}$. It should be noted that this is the value predicted for large angular momenta by the Variable Moment of Inertia model [1,2]. A second plot of $\mathop R\nolimits_J \quad (\mathop R\nolimits_J =\mathop E\nolimits_{\mathop J\nolimits_1^+ } /\mathop E\nolimits_{\mathop 2\nolimits_1^+ } )$ vs. $J$ reveals curves described by power regressions where $0.66\le b\le 1.81$. Graphs of $b$ vs. neutron number ($N)$ reveal V-shaped patterns for many nuclei, with the lowest exponent corresponding to a magic $N$. In addition, sharp jumps in exponents are seen at the $(N=88)\to (N=90)$ transition point in several nuclei. A third chart -- an abbreviated energy level diagram including $\mathop 0\nolimits_1^+ $,$\mathop 0\nolimits_2^+ $,$\mathop 2\nolimits_1^+ $,$\mathop 2\nolimits_2^+ $, and $\mathop 4\nolimits_1^+ $states illustrates the energy increases at magic numbers, along with the near-degenerate two-phonon triplet of $\mathop 0\nolimits_2^+ $, $\mathop 2\nolimits_2^+ $, and $\mathop 4\nolimits_1^+ $ - most clearly observed in isotopes of Z=28,34,36,38,44,46, and 48. Lastly, a fourth chart of $\mathop E\nolimits_{\mathop 3\nolimits_1^- } $ against $\mathop E\nolimits_{\mathop 2\nolimits_1^+ } $ shows positive correlation that is well described by equation $E(\mathop 3\nolimits^- )=A-\frac{\mathop B\nolimits^2 }{E(\mathop 2\nolimits_1^+ )}$ - not only for Z=54 [3] but also for Z=36,42-52, and 68. Data obtained through ENSDF database. [1] M.A.J.Mariscotti,G.Sharff-Goldhaber and B.Buck, \textit{Phys.Rev.}\textbf{178,1864}(1969). [2] M.I. Stockmann and V.G.Zelevinsky, \textit{Phys.Lett.}\textbf{41B},19(1972). [3] W.F. Mueller et al.,\textit{Phys.Rev.C} \textbf{73}, 014316(2006). [Preview Abstract] |
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GB.00021: Analysis of Resistive Plate Counter Detector used at Hadron Colliders Alex Burnap Resistive Plate Counters (RPC) used for muon detection in the ATLAS and CMS experiments at the Large Hadron Collider are essentially based on the same design as those currently being installed for the level one muon trigger upgrade of the PHENIX experiment at the Relativistic Heavy Ion Collider. A full size RPC prototype double gas gap RPC was constructed for detector performance studies in the PHENIX RPC assembly laboratory at BNL. The RPC was then taken to UIUC where a setup of scintillators and drift chambers makes it possible to reconstruct cosmic ray tracks with a position resolution of about 1 mm. This tracking makes it possible to characterize RPC efficiencies and position resolution as a function of position in the detector and to study the efficiency near the detector edges and in regions where mechanical spacers in the gas gaps are located. [Preview Abstract] |
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GB.00022: Elastic Compton Scattering from Carbon John Capone, Gerald Feldman A Compton scattering experiment was conducted at MAX-Lab in Lund, Sweden, in which tagged photons of energy E$_{\gamma }$ = 81.5 -- 115.7 MeV were incident on a carbon target. Photons were produced via bremsstrahlung by an electron beam's interaction with an aluminum radiator. The electrons were then deflected by a magnetic field into plastic scintillator paddles along the focal plane, allowing the energies of the corresponding photons to be tagged. Photons scattered from the carbon target were then detected by three large-volume (50 cm $\times $ 50 cm) NaI scintillator detectors located at 60\r{ }, 120\r{ } and 150\r{ } from the photon beam axis. The elastic Compton scattering peak was identified by setting a time window on ``true'' coincidences between the NaI detectors and the tagger focal plane array. The data required a background subtraction to remove unwanted contributions to the energy spectra from ``random'' events such as cosmic rays and untagged photons. After this subtraction, the residual background was fit in order to determine the integral of the elastic scattering peak. With this experimental yield, normalization factors such as the target thickness, photon flux and NaI detector solid angles were applied to determine the absolute cross section. The results for the differential cross section will be presented as a function of angle and energy and will be compared to published values from the literature. [Preview Abstract] |
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GB.00023: Electropolishing Copper Substrates for Niobium Thin-Film Coatings in SRF Technologies Andrea Carlini, Anne-Marie Valente-Feliciano Electropolishing (EP), the electrochemical removal of contaminants and microscopic smoothing of metallic surfaces, has been used for surface preparation of superconducting radio frequency (SRF) cavities. Cu substrate EP is particularly useful for Nb thin-film coatings as surface roughness and impurities can negatively influence the efficiency of these superconductors. During the EP process, Cu atoms on the highest peaks of the surface ionize and travel away from the substrate, resulting in a smoothing of the surface. The focus of this project was to improve Cu EP by optimization of various parameters. Here it is shown that a high and low current density (J) was identified for optimum polishing. Variables such as bath age, previous mechanical polishing, time, electrode distance, and J combinations were tested to analyze the effect on Cu samples. The results indicate that considerable leveling of the copper surface is achievable through optimization of the considered parameters. Significant improvements in the efficiency and maximum accelerating field of Cu/Nb cavities may be achievable through this improved process. [Preview Abstract] |
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GB.00024: Development of a Conversion Electron Source for Timing Measurements and the Determination of Angle Dependent Detector Response in the UCNA Experiment A.J. Cetnar, L. Broussard, R.W. Pattie, A.R. Young The beta-asymmetry from polarized neutron beta-decay is proportional to (v/c)Acos$\theta $, where $\theta $ is the emission angle of the beta particles, A is the beta-asymmetry parameter with a small energy dependence, and $v$ is the speed of the beta-particle. In the UCNA experiment, ideally, the average value of cos$\theta $=1/2 and the detected energy of the electrons determines the v/c factor. Scattering and energy loss in non-active materials in the trajectory of the emitted electrons introduces an angular dependence to the efficiency and response of the detectors. This deviation is corrected in the UCNA experiment based on results from Monte Carlo simulations. In order to directly establish the angle dependent corrections, we have developed a timing source that can be placed in the 1T magnetic field in the beta spectrometer. An avalanche photodiode detects Auger electrons emitted in coincidence with conversion electrons from $^{113}$Sn providing the time of flight for the conversion electrons. Because the conversion electrons are essentially monoenergetic, the time of flight is determined by the pitch angle of the trajectories in the magnetic field of the spectrometer. We present an evaluation of the performance of the timing source and expected response in the UCNA experiment. [Preview Abstract] |
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GB.00025: Structure of even-A nuclei in the neutron-rich region of the nuclear chart predicted by the r-process Raul Chavarria, Ani Aprahamian The main goal in nuclear physics is the study of the properties of the nucleus as a function of protons and neutrons that make it up. Three particular areas of interest in nuclear physics are the study of masses, structures and half-lives of nuclei. Much is known about nuclei close to stability but lack of sophisticated equipment has limited research on exotic nuclei in the neutron-rich region of the nuclear chart predicted by the r-process. By studying the energies of the 4+ and 2+ excited states of nuclei to the ground state of even-A nuclei, it is possible to roughly determine the structure of nuclei. Looking at how this ratio changes as a function of the P factor, it is possible to see how the structure changes for nuclei as the neutron and proton count move away from close shell magic numbers. This provides an important tool to study the structure of exotic nuclei whose quadrupole moment is very difficult to see experimentally. I will discuss specific predictions on the structure of even nuclei at A$\sim $110. [Preview Abstract] |
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GB.00026: Simulation on the Charged Particle Response of the STAR Heavy Flavor Tracker Pixel Detector Alex Cimaroli, Xin Li The main task of the STAR experiment, located at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, is to study the quark-gluon plasma (QGP), which is believed to have been created a few microseconds after the ``Big Bang.'' Heavy quarks are ideal tools for studying the properties of QGP. The Heavy Flavor Tracker (HFT) is the central part of the STAR future heavy flavor physics program and will enable STAR to directly measure heavy flavor mesons. The core of HFT is a pixel detector (PIXEL) using CMOS Active PIXEL Sensor. This poster will describe the development of a detailed simulation of the pixel detector response to charged particles and the corresponding fast simulation that dramatically enhances the simulation speed with little sacrifice in accuracy. The full simulation randomly generates ionized electrons along an incoming track and diffuses the electrons inside the pixel array until they are collected by the electronics or recombined inside a pixel. With the same result, the fast simulation, which quickens processing time from one hour to 5 seconds, generates a grid inside a single pixel and create a map of probability distribution functions for a single ionized electron generated from a grid point. We will also discuss the study of pixel detector position resolution using a simple clustering algorithm. [Preview Abstract] |
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GB.00027: Signal Efficiency of the Resistive Plate Chambers in the PHENIX Forward Trigger Upgrade Mark Coley PHENIX is an experiment at the Relativistic Heavy Ion Collider (RHIC) that studies polarized proton-proton and heavy ion collisions. PHENIX is in the process of upgrading the forward muon trigger to improve its capabilities of studying W-bosons. By triggering on single, high transverse momentum muons, new observations on the spin structure of a proton will be obtained. The trigger upgrade will consist of four stations of Resistive Plate Chambers (RPCs) with two stations on each side of the interaction region. Inside an RPC, there are several copper strips which form a signal plane. When a charged particle travels through the adjacent gas gaps a signal is induced on these strips. This signal propagates from the copper strip to the readout electronics. In the readout electronics, the signal is amplified and sent to a discriminator. Care must be taken when setting the chamber high voltage and the readout electronics threshold to balance the detector efficiency and noise. Lowering the threshold increases the efficiency of detecting muons but also increases the background interference. These RPCs are tested on a cosmic ray test stand to determine the optimal operating conditions. This poster will describe the RPCs, how the signal propagates out of the chamber and how the high voltage and threshold affect performance. [Preview Abstract] |
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GB.00028: Testing Analysis Algorithms for the $^2\rm{H}(e,e'p)n$ Reaction Calina A. Copos, Gerard P. Gilfoyle We have measured the asymmetry $A_{LT}\prime$ of the $^2\rm{H}(e,e'p)n$ reaction in quasielastic kinematics at a beam energy of 2.56GeV over a 4-momentum transfer range $Q^2=0.2-2.0(GeV/c)^2$ with the CLAS detector at Jefferson Lab. We have performed a Monte Carlo simulation of the reaction in order to test the analysis code used to extract $A_{LT}\prime$ associated with the fifth structure function. The Hulthen distribution was used to select the magnitude of the internal Fermi momentum of the target nucleon and the direction was chosen isotropically. The direction and Fermi momentum of the target nucleon were weighted by integrating the elastic cross section in the frame of reference of the moving nucleon over the CLAS acceptance. A fit to the measured $A_{LT}\prime$ was incorporated into the Monte Carlo simulation to model the fifth structure function. The GEANT3-based code GSIM was used to simulate the CLAS detector. Monte Carlo events were analysed with the same code used to extract $A_{LT}\prime$ from the experimental data. We simulated quasielastic scattering at a beam energy of 2.56GeV using two polarities of the CLAS toroidal magnet.The asymmetry extracted from Monte Carlo events is consistent with the input function for the asymmetry within the uncertainties of the calculation. [Preview Abstract] |
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GB.00029: Generation of Unprecedented high Electric Fields with Pyroelectric Crystals Sarah Crimi, Werner Tornow, Zach Corse Since a few years pyroelectric crystals in a deuterium gas environment have been used to produce neutrons via the $^{2}$H(d,n)$^{3}$He reaction. The figure-of-merit for neutron production in the energy region of interest is about IE$^{3/2}$, where I is the deuterium ion current and E is the associated ion energy. Therefore, it is important to maximize E. Using single and double crystal arrangements with electric field enhancing nano-tips, the highest positive potentials reported in the literature were 115 keV [1] and 250 keV [2], respectively. Using longer LiTaO$_{3}$ crystals than commonly employed (2.5 cm versus 1.0 cm) and without attaching a nano-tip, we have produced positive deuterium ion beams of energies up to 325 keV with a single crystal during the cooling phase from 130 $^{\circ}$C to 0 $^{\circ}$C. In a double crystal arrangement we have obtained positive ion energies of up to 390 keV. Details of our experimental approach will be presented.\\[4pt] [1] B. Naranjo et al., Nature 434, 1115 (2005).\\[0pt] [2] D. Gillich et al., Nucl. Instr. Meth. in Phys. Res. A 602, 306 (2009). [Preview Abstract] |
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GB.00030: Constructing the Fermilab E-906 Spectrometer to Investigate Proton Anti-Quark Asymmetry Mandi Crowder Fermilab E-906 is a fixed target experiment that has a primary goal of extracting the sea anti-quark structure of the proton. For E-906, Abilene Christian University (ACU) is responsible for the design and construction of the downstream hodoscopes that will form a primary part of the event trigger. The detector design is based on the E-866/NuSea spectrometer, which determined the proton's excess of anti-down quarks relative to anti-up quarks over an extended kinematic range. The improvements over E-866/NuSea include replacing the scintillators and light guides to ensure better efficiency. E-906 will also add double-ended read-out on the three farthest downstream hodoscopes to provide better timing and trigger efficiency. The required 224 photomultiplier tubes (PMTs) will be tested to find their approximate operating voltages and maximum counting rates. The method to find the operating voltage used the Compton edge of Cesium-137 found with a Multi-Channel Analyzer (MCA) to compare all of the PMTs. All other testing procedures, results, and design plans will be presented. [Preview Abstract] |
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GB.00031: Improved detectors for the new muon g-2 measurement Gregory Damhorst A precision measurement of the muon anomalous magnetic moment (g-2) is one of the most promising efforts for the detection of new physics beyond the standard model. A new proposal to perform the measurement at Fermi National Accelerator Laboratory promises to reduce uncertainty in the measurement from 0.54 ppm to 0.14 ppm, improving the measurement's power in discriminating various extensions to the standard model. To accomplish this greater precision, the new g-2 measurement will require improved detectors and data acquisition techniques. Calorimeters made of tungsten and scintillating fiber (SciFi) will be used for the detection of weak decay electrons. This design is preferred over the grooved lead/SciFi calorimeters used in past g-2 measurements for its simple assembly and smaller radiation length. Photons produced in the scintillation process will be directed to photomultipliers for electronic readout through foil-lined acrylic light guides which must concentrate photons with minimal loss within a limited available space. The challenge of developing an optimal detector design is being addressed by the University of Illinois Nuclear Physics Group through Monte Carlo simulations and tests of prototype calorimeters and light guides. Significant aspects of this project include determining optimal calorimeter module size, light guide geometry, and photomultiplier style. [Preview Abstract] |
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GB.00032: Identifying the induced depletion of $^{166m }$Ho B.A. Detwiler, N. Caldwell, G.P. Trees, J.J. Carroll, N. Pereira, M. Litz, G. Merkel, J. Schumer Current nuclear data indicates that incoming photons below 300 keV may allow for an induced depletion of the $^{166}$Ho isomer. Such photons will excite the nucleus of a sample of $^{166m}$Ho up to a higher state. From there, the nucleus could decay back to this first metastable state or take a separate decay path down to the ground state. While the first metastable state has a half-life of 1200 years, such an induced depletion would allow the nucleus to decay to its ground state in just fractions of a second. From there, further beta decay occurs on the order of about 24 hours. During the induced depletion cascade, a 136 keV gamma ray will be emitted from a level that has a 185 $\mu $s half-life and is above the initial isomer. A detection system has been designed to detect this unique photon as well as evidence of the 185 $\mu $s half-life; both are signals that the induced depletion has occurred. A cerium-doped lanthanum chloride (LaCl$_{3}$:Ce) scintillator coupled to a gated photomultiplier tube is used to observe gamma rays from the isomeric sample of $^{166}$Ho. Timing data of the unique photon will be recorded in between bremsstrahlung pulses from an electron linac. First results of this experiment will be discussed. [Preview Abstract] |
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GB.00033: Data analysis for spectroscopy of $^{108}$Ag via single-neutron transfer T. Detwiler, B. Detwiler, G.P. Trees, I.N. Mills, T. Harle, N. Caldwell, S.A. Karamian, T. Shizuma, T. Ishii, H. Makii, E. Ideguchi, P.M. Walker, R.S. Ckakrawarthy, J.J. Carroll $^{108}$Ag contains an isomeric state with excitation energy of 110 keV and a half-life of 418 years. A level above this state with excitation energy of 364 keV provides decay paths to both the isomeric and ground states; therefore, this level might serve to enable an induced depletion of the isomer. To obtain improved level data, an experiment was conducted at the tandem accelerator facility, JAEA, Tokai where a beam of $^{18}$O ions were incident on a $^{107}$Ag target. Arrays of Si $\Delta $E-E detectors and HPGe detectors were arranged to detect projectile-like ions and gamma rays, respectively. Among numerous reactions, single-neutron transfer produced excited states in $^{108}$Ag with scattered projectile-like $^{17}$O ions. This poster will discuss data sorting to extract these events and preliminary analysis of the corresponding gamma-gamma coincidence matrix. [Preview Abstract] |
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GB.00034: Determination of environmental dependence of the $\beta^{-}$ decay half-life of $^{198}$Au A. Dibidad, J. Goodwin, J. Hardy A series of articles by the C. Rolfs group [1] claimed changes in the half-lives of isotopes undergoing $\alpha $, $\beta ^{-}$, $\beta ^{+}$, and electron-capture decays as the temperature reduced to 12 K from room temperature. These isotopes were contained in metallic, conductive environments, such as Au, Cu, and Pd, but it was also suggested that the half-life is different in an insulator. One publication [1] reported the half-life of $^{198}$Au in a gold metal environment to change by 3.6 $\pm $1.0{\%} between room temperature and 12 K. Until then, radioactive half-lives were considered independent of environmental factors. We repeated the measurements of the $^{198}$Au half-life in a gold metal environment under similar conditions as ref. [1] and demonstrated [2] that the half-life is the same at both temperatures within 0.04{\%}, two orders of magnitude below the original claims. In the experiment reported here, we measured the half-life of $^{198}$Au in an insulated environment -- gold (III) oxide -- at room temperature. Preliminary results indicate there is no difference in the measured half-life in an insulator as compared in a conductor. \\[4pt] [1] T. Spillane \textit{et al}, Eur. Phys. J. A 31, 203 (2007) \\[0pt] [2] J.R. Goodwin \textit{et al}, Eur. Phys. J. A 34, 271 (2007) [Preview Abstract] |
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GB.00035: Assembling Resistive Plate Chambers for the PHENIX Detector Kirk Drummond A fast muon trigger for the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) will enable the study of flavor separated quark and anti-quark spin polarizations in the proton through the analysis of single spin asymmetries for $W-$boson production in proton-proton collisions. The Phenix experiment is capable of measuring high momentum muons at forward rapidity, but the current online trigger does not have sufficient rejection to sample rare leptons from W-decay at the highest luminosities at the Relativistic Heavy Ion Collider. This upgrade will enhance our ability to collect and analyze muons that decay from W-bosons produced in polarized proton-proton collisions. This upgrade is comprised of half-octants which encompass three different Resistive Plate Chamber (RPCs) modules that encase a sandwich of copper, mylar, gas gaps, and a signal plane. The summer of 2009 marked the start of this full production, with teams from many institutions contributing to the production in the assembly tent at Brookhaven National Lab. The North Arm Station 3 part of the upgrade is scheduled to be installed in the fall of 2009, and the remaining stations will be installed by the fall of 2011. [Preview Abstract] |
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GB.00036: Development of a large acceptance, tracking gas ionization chamber Christopher Dupuis, J.C. Blackmon, L.E. Linhardt, M. Matos, D.W. Bardayan, G. Rogachev, I. Wiedenh\"oever The detection of heavy ions at forward laboratory angles provides an efficient and selective technique for identification of reaction channels in measurements with radioactive ion beams in inverse kinematics. This can be very important in some experiments as the intensity and purity of radioactive ion beams is often low. We are developing a large-acceptance (more than 60 msr), gas ionization chamber that is designed for such cases. The counter provides atomic number selectivity through relative energy loss measurements from 3 anodes. The trajectory of ions is also measured using resistive-wire readout from proportional counting wires. We have modeled the performance of the counter and are testing its performance using alpha radioactive sources. [Preview Abstract] |
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GB.00037: Reconstruction of Radiation Source Locations Using Goodness-of-Fit Tests on Spectra Obtained from an HPGe Detector Len Evans High purity germanium (HPGe) detectors are ubiquitous in nuclear physics experiments and are also used in numerous low radioactive background detectors, including the proposed {\sc Majorana} experiment. Spatial reconstruction of the location of radiation sources from spectral distortions could be used to locate unwanted backgrounds or ``hot-spots'' inside the detector shield. The effect of the position of $^{60}$Co and $^{137}$Cs point sources on the shape of spectra were studied with both Monte Carlo and HPGe detector measurements. We briefly confirm previous work on the position dependence of relative heights of peaks. Spectra taken with the radiation sources placed at locations around the detector were then compared using the Kolmogorov-Smirnov (K-S) goodness-of-fit test. We discuss the position reconstruction accuracy of this statistical method, which is promising. [Preview Abstract] |
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GB.00038: Understanding the Isotopic Fragmentation of a Nuclear Collision T.C. Fagan, L.W. May, S. Wuenschel, Z. Kohley, A.S. Botvina, S.J. Yennello The Statistical Multi-fragmentation Model (SMM) coupled with the Deep Inelastic Transfer Model (DIT) was used to simulate the production and fragmentation of quasi-projectiles produced in the reactions of $^{78,86}$Kr+$^{58,64}$Ni at 35 MeV/u. In order to compare the theoretical results to experimental data taken on the NIMROD-ISIS charged particle array, the simulated data was filtered to account for the acceptance of the detector and experimental source cuts. An isoscaling analysis was performed on the resulting fragments by comparing fragment yields from neutron-rich and neutron-poor reconstructed quasiprojectiles. The results from the simulation show qualitative agreement with the experimental data. The isoscaling parameter $\alpha $, which is related to the symmetry energy, decreases with increasing excitation energy. This result is seen in both the filtered and un-filtered simulation demonstrating that the experimental observation of the decreasing $\alpha$ /$\Delta $ value is not due to the detector bias or source cuts. Furthermore, the isoscaling was investigated as a function of the source N/Z bin widths and a trend in $\alpha$ as a function of changing bin width is observed. [Preview Abstract] |
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GB.00039: Transport Properties of a Perturbative Quark-Gluon-Plasma John Fuini, Nasser Demir, Steffen Bass Ultrarelativistic heavy-ion collisions may create a deconfined state of QCD matter, called the Quark Gluon Plasma, which was the state of the early Universe shortly after the Big Bang. The very low shear-viscosity over entropy density ratio (eta/s) of the QGP discovered at RHIC has attracted a lot of interest, due to the use of the AdS/CFT conjecture in string theory to calculate a possible lower bound of 1/4pi for eta/s in a QCD-like theory. In this work, we use the Parton Cascade Model to calculate eta/s of a weakly interacting QGP. The PCM has been successfully applied to the study of the non-equilibrium time evolution of the QGP created in heavy ion collisions at high temperatures. Here we perform a study of QGP matter in equilibrium and, using the Kubo formalism, calculate eta/s as a function of temperature and system composition. We find values of eta/s which are too high to explain the near ideal fluid behavior observed at RHIC. By increasing the coupling constant beyond the applicability of perturbative QCD, we find eta/s values compatible with the RHIC data. Our results confirm the strongly interacting nature of the QGP at RHIC and provide a baseline for eta/s values to be expected at the LHC, where higher temperatures are thought to dominate the evolution of the system. [Preview Abstract] |
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GB.00040: Timing Resolution of the Prototype Resistive Plate Chambers for the PHENIX Trigger Upgrade Kyle Gainey The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC) studies polarized proton-proton collisions to understand the spin structure of the proton. The muon trigger in PHENIX is being upgraded to improve its ability to select high pT single muons such as those produced in the decay of W-bosons. Two prototype Resistive Plate Chambers (RPCs) have been in the interaction region taking data through the run that ended earlier this year. The addition of the RPCs to PHENIX will provide precision timing information to the muon reconstruction. Among other benefits, this will allow for the differentiation between particles originating from collisions at the interaction point and background particles originating elsewhere. The additional capability to reject background will be important at the higher energies needed to study W-bosons. The 2009 run was the first time RHIC collided polarized protons at 500 GeV and thus the background levels were initially imprecisely known. This poster will focus on how the prototype chambers performed during this high energy run and include details about their timing resolution. [Preview Abstract] |
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GB.00041: Calibrations of Beta and Gamma Detector Efficiencies Camille Garcia, Xiaodong Tang, Chi Ma The $^{12}$C+$^{13}$C reaction has been studied at sub-barrier energies from Ec.m.=2.55 MeV to 4.7 MeV by detecting the decay of $^{24}$Na resulting from the proton decay branch of the compound nucleus $^{25}$Mg. To determine the absolute cross section, two different methods, coincidence method and sum peak method, have been applied to determine the detector efficiency and the total amount of the produced $^{24}$Na. A calibrated $^{22}$Na standard source has been used to validate the sum-peak method. The angular correlation effect of the two coincident gamma rays from the $^{24}$Na decay was corrected by means of the Monte Carlo simulations. Applying the sum-peak method to the $^{22}$Na experimental data, the reference value for the activity and the activity obtained experimentally agreed within a range of 1\%. [Preview Abstract] |
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GB.00042: Study of Charmonia States in Vacuum and High Density Medium Juan Garcia Quantum Chromodynamics (QCD) predicts a hot state of quark matter with a critical temperature of about Tc=2*1012 K (170 MeV), the Quark Gluon Plasma (QGP). Heavy quarks (charm and bottom) provide a probe for the QGP because of their large masses which are much greater than Tc. We study bound states these quarks form, in particular Charmonium, a charm-anticharm bound state. For our study we take a non-relativistic approach using different potential models to study the system in both vacuum and medium by solving Schr\"odinger's Equation for different eigen states and associated eigen energies. [Preview Abstract] |
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GB.00043: Particle Induced X-Ray Emission Analysis of Atmospheric Aerosols Collected in Upstate New York Colin Gleason, Charles Harrington, Katie Schuff, Scott Labrake, Michael Vineyard Elemental analysis of atmospheric aerosols collected in the historic Stockade District of Schenectady, New York, was performed using particle induced X-ray emission (PIXE) spectroscopy. This is part of a systematic study in the Mohawk River Valley of upstate New York to identify the sources and understand the transport, transformation, and effects of airborne pollutants and the connection between aerosols, the deposition of pollution, and the uptake of pollutants by wildlife and vegetation. The atmospheric aerosols were collected with a nine-stage cascade impactor that allows for the analysis of the particulate matter as a function of particle size. The samples were bombarded with 2-MeV proton beams from the Union College Pelletron Accelerator and the energy spectra of the X-rays were measured with a silicon drift detector. The X-ray spectra were analyzed using GUPIX software to extract the elemental concentrations of the particulate matter. The sample collection and analysis will be described, and preliminary results will be presented. [Preview Abstract] |
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GB.00044: Eliminating the effect of SRC beam-energy spread on the BigRIPS focal plane Yusuke Goto, Takahiro Nishi At RIKEN RIBF, precise and systematic studies on the 1s binding energies and widths of pionic-Sn atom usig the Sn(d,$^3$He) pion-transfer reaction are planned, but a relatively large energy spread of the RIKEN Superconducting Ring Cyclotron (SRC) poses a difficulty in achieving the required resolution. ``Dispersion matching'' is a way of adjusting the optical settings of the beam line to overcome this problem. It makes positions of particles on a focal plane independent of the beam-momentum spread, while ensuring the particles with different Q values focused at the different positions on the focal plane. We recently made an experiment for testing the dispersion matching at RIKEN. In this experiment, a $^{14}$N beam of 250 MeV/nucleon was used; the value of energy per nucleon being the same as that of the deuteron which will be used in the experiment on pionic-Sn atom. We tried some ion-optical settings and verified that particles with a finite momentum spread could be focused to one point. In the Hawaii meeting, we will present the detailed analysis of this test experiment. [Preview Abstract] |
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GB.00045: Monte Carlo Simulation of Neutron Background Sources in the Measurement of the $^{12}$C($\alpha $,$\gamma )^{16}$O Reaction Rate Kevin Gullikson, Claudio Ugalde The $^{12}$C($\alpha $, $\gamma )^{16}$O reaction rate strongly affects the relative abundances of chemical elements, as well as when core collapse supernovae occur. In a proposed experiment, a water-filled bubble chamber will be used to measure the reverse reaction rate. A potential background source is photoneutrons from the $\gamma $-ray beam collimator entering the bubble chamber and generating a false signal. To minimize this effect, a Monte Carlo simulation has been performed to compare the number of photoneutrons created in lead, copper, and aluminum collimators. The simulation also compared the effectiveness of concrete, polyethylene, and water neutron shields. It was found that 30 cm of copper would be an effective collimator, and 30-40 cm of polyethylene a satisfactory neutron shield. [Preview Abstract] |
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GB.00046: Using Geometry Description Markup Language to store the geometry of FNAL E-906 Tyler Hague The primary goal of FNAL E-906 is to investigate the ratio of d(bar)/u(bar) in the nucleon sea. To do this, the Drell-Yan cross section ratio will be measured in proton-proton and proton-deuterium collisions. FNAL E-906 is utilizing Geometry Description Markup Language (GDML) to describe the geometry of the spectrometer. GDML is capable of describing the spectrometer in great detail and is fully functional with GEANT4 and ROOT. By using this we will have a common geometry input for all of our software codes including two Monte Carlo simulations, primary data analysis code, and a ROOT-based event display. The use of such a language creates the need for an easy way to read it and extract data, as well as to update the geometry when changes are made. A tool has been developed to convert a GDML file into an experiment-specific, easy to read ASCII file. Another tool is in development to create a simple interface to update a GDML file without knowledge of the language. These tools use ROOT's geometry tree to traverse the volumes described in GDML. This poster will describe the advantages of using GDML and its implementation. [Preview Abstract] |
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GB.00047: Detailed Gamma Ray Spectroscopy of 31Si using GAMMASPHERE and MICROBALL Leanne Hamilton, Paul Fallon, Stefanos Paschalis, Marina Petri, Augusto Moicchiavelli, Rod Clark, Peter Bender, Callum Hoffman, Samuel Tabor, Vandana Tripathi, Demetrios Sarantites, Walter Reviol, Xinfeng Chen, C. Chiana, Robert Janssens, Shaofei Zhu, Torben Lauritsen, L. McCutchan, Yoshuke Zoh I participated in an experiment carried out at Argonne National Laboratory to investigate the relation between normal and intruder states in the s-d shell of neutron-rich nuclei. The experiment used a 25 MeV 18O beam incident on an 18O target with a thick Ta backing. Gamma rays were detected by the 101 Compton-suppressed HPGe detectors that comprise the GAMMASPERE array and channel selectivity was provide by MICROBALL's 95 CSI(Tl) scintillators. This work focuses on the nuclear structure of 31Si through measuring nuclear state decays. $\alpha -\gamma $ and $\alpha -\gamma -\gamma $ coincidence data are being analyzed by the in-house software package GNUSCOPE. Preliminary spectroscopic results have currently verified 13 previously known transitions and 22 new gamma ray de-excitations have been identified. Both the positive and negative parity states have so far compared well with shell model calculations using the WBP-a interaction. [Preview Abstract] |
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GB.00048: Study of dark matter and neutrino by means of thin NaI(Tl) Katsuya Harada The MOON/PICO-LON consists of two thin NaI(Tl) crystal is applied to search for 0$\nu\beta\beta$ decay and WIMPs dark matter. The MOON/PICOLON has great advantages to both 0 $\nu\beta\beta$ decay and WIMPs dark matter; \begin {enumerate} \item 100\% of natural abundance of odd $A$ nuclei ($^{23}$Na and $^{127}$I). \item NaI(Tl) has the good enrgy resolution. \item $^{127}$I has a low energy exited state at 57.6keV which is excited by spin-dependent interaction. \end {enumerate} The detector of two thin NaI(Tl) crystal was tested in Oto cosmo laboratory. The good energy resolution and the low back ground data will be reported. [Preview Abstract] |
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GB.00049: Chamber Performance of Prototype Resistive Plate Chambers for the PHENIX Forward Trigger Upgrade Caitlin Harper The Pioneering High Energy Nuclear Interaction Experiment (PHENIX) is located on the Relativistic Heavy Ion Collider (RHIC) ring at Brookhaven National Laboratory. One of the ultimate goals at RHIC is to obtain a more accurate understanding of a proton's intrinsic spin structure through polarized proton-proton collisions. The parity violating decay of W-bosons created in some of these collisions allow for the determination of flavor separated quark distribution functions. Recently, PHENIX has been focusing on the construction and installation of Resistive Plate Chambers (RPC's) as part of upgrade to the PHENIX muon trigger. These RPC's are useful in the selection of high transverse momentum muon events from a background of low transverse momentum muon events. The second RPC station for the North side of the detector is still in the prototype stage. In order to make sure that this RPC is as efficient as possible, it is vital to reduce the amount of noise in the chamber. Efforts to measure and decrease the noise rates for the prototype will be further discussed. [Preview Abstract] |
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GB.00050: Elemental Concentrations as a Function of Particle Size for Aerosol Samples Collected in Upstate New York from PIXE Charles Harrington, Colin Gleason, Katie Schuff, Scott LaBrake, Michael Vineyard Using proton induced X-ray emission (PIXE) spectrometry, aerosol samples were studied to measure concentrations of airborne pollutants around Schenectady, New York. The health and climate effects of atmospheric aerosols depend on the size distribution of the particulate matter, which also is important for identifying the sources and for understanding the transport, transformation, and removal processes. For this reason, the aerosol samples were collected using a cascade impactor that separates the particulate matter into ten diameter ranges that allows for the analysis as a function of particle size. Beams of 2-MeV protons, provided by the Union College Pelletron Accelerator, were incident on the thin Kapton impaction foils, producing X-rays. The energy and intensity of the X-rays were measured using a silicon drift detector. The X-ray spectra were fit using the GUPIX software package to determine the elemental concentrations of the aerosols as a function of particle size. The analysis will be discussed and the elemental concentrations as a function of the size of the particulate matter will be presented. [Preview Abstract] |
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GB.00051: One-proton knockout from $^{82}$Ge B.A. Hartl, J.L. Palardy, L.A. Riley, T.R. Baugher, D. Bazin, A. Gade, T. Glasmacher, G.F. Grinyer, S. McDaniel, R.T. Meharchand, A. Ratkiewicz, K.A. Walsh, D. Weisshaar We report the results of an experiment performed at the National Superconducting Cyclotron Laboratory at Michigan State University (NSCL) in which the one-proton knockout reaction $^{9}$Be($^{82}$Ge,$^{81}$Ga)X was observed. The $\approx$ 90 MeV/nucleon exotic cocktail beam had primary components $^{82}$Ge and $^{83}$As. The incoming beam was purified with the A1900 fragment separator, gamma rays emitted by the reaction products were detected with the Segmented Germanium Array (SeGA), and the reaction products were identified in the S800 magnetic spectrograph. We measured gamma rays in coincidence with incoming $^{82}$Ge and outgoing $^{81}$Ga, as well as the one-proton knockout cross section. Preliminary Results are discussed. [Preview Abstract] |
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GB.00052: Development of Thermal Ionizer for the Search of the Electron Electric Dipole Moment Tomohiro Hayamizu, Akihito Oikawa, Toshiya Takahashi, Hidetomo Yoshida, Masatoshi Itoh, Yasuhiro Sakemi A non-zero Electric Dipole Moment (EDM) of an elementary particle means the violation of the time-reversal symmetry and the CP violation assuming the CPT invariance. The super symmetry model (SUSY) predicts the EDM large enough to be observed with the modern experimental technique. In alkali atoms, an electron EDM results in an atomic EDM enhanced by the factor $\sim $Z$^{3}$\textbf{$\alpha $}$^{2}$, especially francium (Fr) has the largest enhancement factor $\sim $ 1150. However Fr is a radioactive atom with a finite life time, we need to establish the technique to produce over 10$^{7}$ atoms/sec, cool and collect them quickly into laser trap apparatus as a cold dense cloud of neutral atoms to measure the EDM accurately. Thermal Ionizer produce the high intensity Fr ion using a fusion reaction of $^{18}$O+$^{197}$Au$\to ^{210}$Fr+5n with a primary beam energy E$^{18}_{O }\sim $100 MeV. This ionizer consists of the Au target surrounded by the high temperature oven to stop the ion spreading out. Thanks to the small extraction electrode hole, we can realize the small emittance Fr beam, and the high transmission efficiency. We have achieved to produce over $\sim $10$^{4}$ atom/sec, and transport them along 3 meter without losing the Fr ions. [Preview Abstract] |
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GB.00053: PIXE Analysis of Ceramic Artifacts Elizabeth High, Larry Lamm, Mark Schurr, Edward Stech, Michael Wiescher Particle Induced X-ray Emissions, or PIXE, is a nuclear physics technique used as a non-destructive material analysis method which gives a detailed and comprehensive profile of the elemental composition of a target. Using the University of Notre Dame KN and FN accelerators in the ISNAP laboratory a beam of particles, here protons, is accelerated and used to knock out electrons from lower orbitals within the target resulting in characteristic X-rays. Under optimum operating conditions data from PIXE can not only give information about which elements are present in a sample but also their relative abundances in parts per million. In a previous run done in collaboration with the Anthropology Department at the University of Notre Dame pottery shards from the Collier Lodge, located in northwest Indiana, were analyzed and only relative abundances were able to be compared between samples. We are now implementing a new setup into the beam-line which will incorporate the ability to take Rutherford Back Scattering, or RBS, measurements of the beam during the PIXE runs, which will allow for a standard normalization for the runs and give the facility the ability to acquire a more absolute and quantitative analysis of the data. Initial results using the same pottery shards as a comparative data set will be presented. [Preview Abstract] |
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GB.00054: Lifetime Measurements in $^{71}$Se A.R. Howe, R.A. Kaye, N.R. Baker, S.R. Arora, J.K. Bruckman, S.L. Tabor, T.A. Hinners, C.R. Hoffman, S. Lee, J. D\"{o}ring In the light selenium isotopes, $^{71}$Se appears to be a transitional nucleus, showing signs of competing single particle and collective structures, but its level structure is not well known. The present work measured lifetimes in $^{71}$Se in order to quantify the degree of collectivity as a function of spin as the configuration of the unpaired neutron changes. $^{71}$Se nuclei were produced at high spin by a $^{54}$Fe($^{23}$Na,$\alpha$pn) fusion reaction at 80 MeV conducted at Florida State University. Fifteen lifetimes were measured from the resulting gamma-ray coincidence data using the Doppler-shift attenuation method. Experimental transition quadrupole moments $Q_t$ were inferred from the lifetimes and found to be in rough agreement with the predictions of cranked Woods-Saxon calculations. Comparisons with neighboring odd-mass nuclei confirmed that $^{71}$Se exhibits moderate collectivity. Based on coincidence relations and systematic arguments, the level scheme was enhanced and extended to higher spin. A band that was previously assigned positive parity was reassigned as the ``missing'' signature partner of an existing negative-parity band. [Preview Abstract] |
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GB.00055: Radiation Hardness of PHENIX Muon Trigger Resistive Plate Chambers Justine Ide The measurement of quark and anti-quark helicity distributions through parity violating single spin asymmetries in W-production with the PHENIX experiment at RHIC requires new fast muon trigger detectors. PHENIX utilizes Bakelite RPC technology that has been developed for the CMS experiment at LHC. These new detectors will collect data for many years, and it is important to understand the impact the constant radiation exposure in PHENIX will have on the performance of the detectors. Prototype RPCs were exposed to two 0.6 mCi Fe-55 sources that were embedded in the detector gas. The RPC efficiency for cosmic ray detection was measured as a function of the total radiation dose exposure using a cosmic ray tracking detector at UIUC. This poster will discuss the radiation hardness of PHENIX Bakelite RPC prototypes, and how the results compare to the requirements at RHIC. [Preview Abstract] |
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GB.00056: Production and use of thermal and cold neutron with tandem accelerator in Kyoto University Tashiro Jin As a graduate research in the Faculty of Science, Kyoto University, we are developing a miniature neutron source and conducting experiments with neutrons produced. Compared with X-rays, neutrons haven't been very widely used for material science until now. It is because there are few facilities for experiments, for an experiment with neutrons requires large-scale ones, such as a nuclear reactor or a high-energy accelerator for spallation reaction. However, neutrons can be also produced by nuclear reactions with much lower energy. Using this method, facilities can be smaller and lower in price than traditional methods.We are building a small neutron source using the tandem accelerator of Kyoto University. To produce neutrons, we used 7Li(p, n) reaction with 3MeV protons. In order to obtain thermal and cold neutrons, we used polyethylene and the mesitylene moderator, which was cooled down to 10K with a refrigerator, respectively. The production of the thermal neutrons was already confirmed, by measuring the time-of-flight of moderated neutrons. However, we could not confirm the production of cold neutrons. Finally, we are planning to utilize thermal neutrons for experiments, such as neutron capture. [Preview Abstract] |
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GB.00057: High-Multiplicity Clustering in the Barrel Electromagnetic Calorimeter at STAR Darrick Jones The STAR detector at RHIC is used to investigate the formation and properties of the Quark Gluon Plasma (QGP), which is believed to be created in heavy-ion collisions. High-p$_{T}$ hadron suppression was discovered and attributed to energy loss of initially scattered partons in the medium. Because direct photons are produced early and do not interact with the evolving medium, a $\gamma $-jet coincidence serves as an effective probe of the medium. For such an analysis, $\pi ^{0}$-decay photons must be distinguished from direct photons. The sub-detector that measures photons is the Barrel Electromagnetic Calorimeter (BEMC), which contains the Barrel Shower Maximum Detector (BSMD). Using the high (position) resolution of the BSMD, an algorithm was previously developed for high-multiplicity events. This algorithm is being modularized for implementation into libraries to be made available to all members of the STAR collaboration. We describe how the algorithm takes advantage of the structure of the BSMD and detail the methods used to distinguish direct photons from $\pi ^{0}$ decay photons. [Preview Abstract] |
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GB.00058: Altering Beamline Components to Reduce the Cost of Prostate Cancer Treatment T. Jones, A. Geibler, R. Zhang, W.D. Newhauser Proton beam therapy is an advanced technique used for the control of localized cancers. Currently it is one of the most cutting edge treatment options for prostate cancer but is still scarce and expensive. The expense is due, in part, to the unique beam collimators and range compensators that are manufactured for each treatment beam. The purpose of this study is to determine whether the custom collimator could be replaced by a reusable multileaf collimator and by eliminating the range compensator. Treatment plans were retrospectively selected for 10 patients who were treated for prostate cancer with 69 Gy delivered by two proton treatment fields. The originals were altered to include the multileaf collimator and to eliminate the range compensators. The dose distributions for each plan were calculated using a treatment planning system, which uses an analytical dose algorithm. They were then verified with Monte Carlo simulations, which are able to take into account individual particle trajectories and calculate dose resulting from stray neutron exposure. The calculated dose distributions for the altered treatments were dosimetrically equal or superior to the original plans. Our findings suggest that the proton-beam treatment technique for prostate cancer could be substantially simplified, thus yielding substantial cost savings. [Preview Abstract] |
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GB.00059: Systematic Uncertainties of Out-of-Plane Measurements of the Fifth Structure Function of the Deuteron Matthew Jordan, Gerard Gilfoyle We have measured the \textsuperscript{2}H$( \vec{e} ,e^\prime p)n$ reaction and the asymmetry $A_{LT}^\prime$ associated with the fifth structure function in quasi-elastic electron scattering from deuterium at a beam energy of 2.56 GeV and over the range $\rm Q^2 = 0.2-2.0 ~ GeV^2$ with the CLAS detector at Jefferson Lab. The data were collected using both magnet polarities to explore different $\rm Q^2$ regions. We extracted $A_{LT}^\prime$ as a function of missing momentum ($p_m$) using spectra weighted by $\sin \phi_{pq}$ where $\phi_{pq}$ is the angle between the electron scattering plane and the plane defined by the ejected proton and 3-momentum transfer. To understand the systematic uncertainties on $A_{LT}\prime$ we varied the positions of the cuts placed on the data used to define the position of the deuterium target, the active region of the electromagnetic calorimeters (EC), the sampling fraction of the EC, and the production of photoelectrons in the Cherenkov counters. These results show a systematic uncertainty of less than 1\% in regions of high statistics and much lower than the statistical uncertainty across the full $p_m$ range. We combined these results with our previous study of systematic uncertainties on our identification of the proton and neutron. Work supported by US Department of Energy contract DE-FG02-96ER40980. [Preview Abstract] |
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GB.00060: Optimized Bunching and Other Improvements to the HIS Ion Source Frederick Jung, Ani Aprahamian, Wanpeng Tan Ion sources for nuclear accelerators produce a constant stream of particles, but for some nuclear reactions, it is useful to have discrete packets of accelerated particles hit the target. Bunchers create these groups of particles that hit a target at a specific point in time. This project found optimum buncher settings for $^{4}$He and proton beams~at Notre Dame's FN Tandem Accelerator. A tantalum target was bombarded with the $^{4}$He and the proton beams. The resultant gamma rays were detected by a BaF$_{2}$ detector placed outside the target chamber. In this way, the resolution of each setting could be determined, and ultimately, the optimal resolution could be found. The optimal resolution was found to be 1.82ns for $^{4}$He, when the buncher was set at 95mV, the sweeper was set at 2V, and the High Voltage Platform was set at 30kV. The optimal resolution for the proton beam was not able to be found, as a clean resolution could not be achieved. This means that a more extensive study of the SNICS ion source needs to be made in an attempt to optimize the beam. [Preview Abstract] |
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GB.00061: Ambient Neutron Flux Measurements at Kimballton Underground Research Facility (KURF) David Kaleko, Reyco Henning, Werner Tornow It is important to accurately measure the ambient neutron flux at the Kimballton Underground Research Facility (KURF) in Virginia for the low background experiments housed there, some of which are associated with the {\sc Majorana} project. This paper presents initial results for measurements of the neutron flux at KURF, which will be compared to those from other sites around the world. [Preview Abstract] |
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GB.00062: Developments of thick solid neon as an active target Nagaaki Kamiguchi, Tetsurou Moriguchi, Akira Ozawa, Sigeru Isimoto One of research subjects in our group is to measure reaction cross sections ($\sigma _R )$ of RI beams. By measuring $\sigma _R $, we can deduce root mean square radii of unstable nuclei. In the measurements of $\sigma _R $, we usually used a carbon as the reaction targets (a few cm thickness). If we use the reaction target as a detector (active target), there are some advantages in the measurements; (1)The events only colliding with the reaction target can be selected. (2)If position information is available, we may define the colliding point inside the target. (3)If energy information is available, we may measure the energy loss of the beams inside the target. As the active target in the $\sigma _R $ measurements, we noticed the solid neon. Since the neon is a noble gas, it is predicted to emit scintillations and work as an ionization chamber for charged particles. Indeed, scintillations from liquid and solid neon have been already observed. We will present production of the thick solid neon ($\sim $30mm thickness), and observations of scintillations and ionization signals from the solid neon. We will also discuss possibility to use the sold neon as the active target in the $\sigma _R $ measurements. [Preview Abstract] |
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GB.00063: Commissioning the STAR Zero Degree Calorimeter as a Local Polarimeter at $\sqrt s =500$ GeV Nathan Kellams, Jason Webb, David Grosnick, Joshua Kellams Experiments over the past thirty years have shown that only approximately 30{\%} of the spin of the proton is due to its valence quarks. The balance must be accounted for by the spin and orbital motions of the quarks, antiquarks and gluons. The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) measures spin asymmetries in both longitudinally and transversely polarized proton-proton collisions to investigate the origin of the proton's spin. Residual transverse components of longitudinally polarized collisions are determined by measuring the polarization vector locally through a transverse single-spin asymmetry in forward hadron production. The Zero Degree Calorimeters (ZDCs) measure both the energy and the position of neutral hadrons produced at forward angles. The analyzing power, A$_{N }$, can be measured in transversely polarized proton-proton collisions and then used with the spin asymmetries observed in longitudinally polarized collisions to extract the polarization vector of the nominally longitudinal beam. In this presentation we will present measurements of A$_{N}$ and its commissioning as a local polarimeter at STAR. [Preview Abstract] |
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GB.00064: Investigation on Periodic Oscillation in Orbital Electron Capture Decay in $^{140}$Pr K. Kisamori, Y. Kuwada, M. Fukuda, D. Nishimura, Y. Fujita, K. Makisaka, R. Matsumiya, K. Matsuta, M. Mihara, T. Suzuki, A. Takagi, T. Yamaguchi, R. Yokoyama According to recent experimental data at GSI , periodic oscillation have been observed in orbital electron capture(EC) of Hydrogen-like ion $^{140}$Pr$^{58+}$. They reported that this phenomenon can be explained by the neutrino mass difference . In order to test the existence of such a periodic oscillation in the decay of $^{140}$Pr under the normal condition, we carried out an experiment to observe the EC decay of $^{140}$Pr at the Van de Graaff accelerator facility in Osaka University. A 4.7-MeV proton beam was used to produce $^{140}$Pr through the $^{140}$Ce(p,n)$^{140}$Pr reaction. Observing K-X rays of Ce emitted just after the EC decay by using a Ge detector, a decay curve of $^{140}$Pr was obtained. We could accumulate the time spectrum of the K-X rays with a good statistics under the low background condition. As a result, a finite-size component of the periodic oscillation could not be observed. We will discuss the experimental details and the result comparing with the GSI result. [Preview Abstract] |
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GB.00065: A follow-your-nose tracker for the NIFFTE TPC R. Kudo, J.L. Klay The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) will employ a compact, pressurized Time Projection Chamber (TPC) to study neutron-induced fission of the major actinides. The software to reconstruct the fragment tracks in the TPC must be capable of sifting through the large volume of sampled data to identify them and determine their (A,Z). This poster presents the status of a ``follow-your-nose" tracking algorithm developed for NIFFTE that proceeds in several stages. It first performs 2-dimensional clustering of raw TPC voxels, followed by mountain-finding and hit-fitting to form hits. It then searches for contiguous hits, starting from the outer edge of the TPC near the pad plane where the population is lower, and working inward toward the target. At each step, the most likely location for the next hit is predicted by a straight-line extrapolation of the current list of hits associated to the track. Track-fitting and error correction are completed once no more hits are found to belong to a given track. The status of the track finder and its performance on simulated events will be presented. [Preview Abstract] |
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GB.00066: Empirical Determination of Effective Germanium Detector Efficiency for Use in Sample Assays Benjamin H. LaRoque, S.R. Elliott, V.E. Guiseppe, R.A. Johnson The {\sc Majorana} project is an experiment which uses gamma ray detectors made of enriched Ge-76 to detect neutrinoless double-beta decay, a process which would indicate that the neutrino is its own antiparticle. Studies of such a rare decay process require very low background levels, making contamination by neutrons at the Earth's surface potentially significant. To quantify this contamination, a piece of enriched germanium was exposed to a high-intensity, broad-spectrum neutron beam before being assayed using a low background gamma ray spectrometer. The analysis of the assay data is dependent on knowing the detector's efficiency at the sample gamma energies. Those values can be interpolated from an empirically determined efficiency curve but producing such a curve is nontrivial because efficiency values are also needed to correct for the coincidence summing effects from gamma cascades and positron annihilations. The process of generating a partial efficiency curve will be presented along with the analysis used to account for coincidence summing and the results of the sample assay. [Preview Abstract] |
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GB.00067: Characterization of the MARS Velocity Filter for Low Velocity Ions K.R. Lawrence, M.C. Alfonso, A. Al-Harbi, E. Berdugo, P.J. Cammarata, C.M. Folden III A program to study the heaviest elements using the MARS separator at the Cyclotron Institute at Texas A{\&}M University has begun. MARS is typically used for light energetic ions, which travel at high velocities ($>$0.08c). The velocities of transactinides after production are on the order of 0.02c. This project aims to characterize MARS velocity filter for low velocity ions. Offline experiments to detect alpha particles emitted were conducted using $^{241}$Am as a source. The source was covered with 50 $\mu $g/cm$^{2} \quad ^{nat}$C to prevent contamination and $^{nat}$Al degraders were used to reduce the velocity of $\alpha $-particles emitted by source. The separator was tuned with the velocity filter off and no degrader in place. The velocity filter was turned on and the electric field was set. The magnetic field was varied and the rate was measured. This was repeated for different electric field settings for degraders with thicknesses of 6 $\mu $m, 12 $\mu $m, and 18 $\mu $m. Data from the offline experiments were analyzed to determine the acceptance of the velocity filter for ions $<$0.06c. The results suggest that the acceptance of the velocity filter decreases as the electric field increases, ranging from $\pm $6.3{\%} to $\pm $2.2{\%} over the fields under study. [Preview Abstract] |
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GB.00068: Designing and Testing a Database for the Qweak Experiment Rebecca Leonard, Damon Spayde The Qweak experiment at Jefferson Laboratory in Newport News, Virginia aims to make the first precision measurement of the proton's weak charge by measuring the parity-violating asymmetry in electron-proton scattering. The weak charge of the proton is directly related to the value of the Weinberg angle, which characterizes mixing between the electromagnetic and weak interactions. The Standard Model makes a prediction for the value of the Weinberg angle, which varies depending on the momentum of the exchanged Z boson. The Qweak experiment will provide a 0.3\% measurement of the Weinberg angle which could indicate new physics if any significant deviation from the prediction is uncovered. A database will be used to store results necessary to make a precise determination of the proton's weak charge such as detector and beam monitor yield, asymmetry, and error as well as control parameters such as the temperature of the liquid hydrogen target. This talk will discuss the design and testing of this database. [Preview Abstract] |
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GB.00069: The $B(E2;4^+_1 \rightarrow 2^+_1) / B(E2;2^+_1 \rightarrow 0^+_1)$ Ratio in Even-Even Nuclei C. Loelius, Y.Y. Sharon, L. Zamick, G. G\"urdal We considered 207 even-even nuclei throughout the chart of nuclides for which the NNDC Tables had data on the energies and lifetimes of the $2^+_1$ and $4^+_1$ states. Using these data we calculated for each nucleus the electric quadrupole transition strengths $B(E2;4^+_1 \rightarrow 2^+_1)$ and $B(E2;2^+_1 \rightarrow 0^+_1)$, as well as their ratio. The internal conversion coefficients were obtained by using the NNDC HSICC calculator. For each nucleus we plotted the B(E2) ratio against A, N, and Z. We found that for close to 90\% of the nuclei considered the ratio had values between 0.5 and 2.5. Most of the outliers had magic numbers of protons or neutrons. Our ratio results were compared with the theoretical predictions for this ratio by different models--10/7 in the rotational model and 2 in the simplest vibrational model. In the rotational regions (for 150 $<$ A $<$ 180 and A $>$ 220) the ratios were indeed close to 10/7. For the few nuclei thought to be vibrational the ratios were usually less than 2. Otherwise, we got a wide scatter of ratio values. Hence other models, including the N$_\textrm{p}$N$_\textrm{n}$ scheme, must be considered in interpreting these results. [Preview Abstract] |
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GB.00070: Spectroscopy of $^{12}$Li Eric Lunderberg, Christopher Hall, Paul DeYoung, Artemis Spyrou, Michael Thoennessen The spectroscopy of neutron-unbound levels in $^{12}$Li is presented. The $^{12}$Li were formed by a two-proton knockout reaction from a 53.4 MeV/u $^{14}$B beam at the National Superconducting Cyclotron Laboratory. The decay energy spectrum was measured with the Modular Neutron Array (MoNA) and Sweeper superconducting dipole magnet experimental setup. The measured decay energy spectrum exhibits one {\it s}-wave resonance and two {\it d}-wave resonances. The {\it d}-wave resonances are modeled by energy-dependent Breit-Wigner line shapes, and the {\it s}-wave resonance line shape was calculated with a scattering length of -13.7 fm\footnote{Yu. Aksyutina {\it et al.}, Phys.\ Lett.\ B {\bf 666}, 430 (2008).}. The specific energies for the two Breit-Wigner resonances are 250$\pm 20$ keV and 555$\pm 20$ keV. The observed widths were dominated by the experimental resolution. [Preview Abstract] |
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GB.00071: Development of a multi-anode ionization chamber Hiroki Makino, Tsuneyasu Morikawa, Tetsuo Noro, Toyokazu Maeda A multi-anode ionization chamber with a Frisch grid has been developed. An immediate purpose is the use in accelerator mass spectrometry (AMS), but the system will also be applied to measurements in heavy-ion nuclear physics. In order to identify the incident heavy ions, the anode is divided into 16 sections so that the ionization distribution along the ion trajectory (Bragg curve) can be analyzed. Layout of the electrodes, for field shaping, has been determined based on calculations by using a computer code, Poisson-Superfish. A good discrimination of $^{36}$Cl ions from background $^{36}$S ions has been shown by the Monte Carlo simulation. For the signal readout, an originally designed charge-sensitive preamplifier was newly made by using conventional operational amplifiers so as to integrate the ionization charge and interface the shaped signal to the electronic modules of existing data acquisition system. These developments are still in progress. In the meeting, the overall performance of the ionization-chamber system investigated by using accelerated heavy ion beams will be presented. [Preview Abstract] |
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GB.00072: Effects of Finite Size of Nuclei on their Thermodynamic Properties E.M. Manion-Fischer, D.C. Fuls, S. Shlomo We investigate the effects of finite size on the thermodynamic properties of nuclei. For this purpose we first calculate the single particle level density, g($\epsilon$), which was derived using the Thomas-Fermi approximation and a finite single particle potential of a trapezoidal form. We carried out these calculations for nuclei with Z=N. We then calculate the level density parameter and the temperature dependence of the excitation energy E* and the entropy S. We demonstrate the important effects the finite size of nuclei has on these values by comparing our results with the values obtained using the commonly adopted Fermi Gas model. [Preview Abstract] |
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GB.00073: Neutron Detection Efficiency in the Crystal Ball and TAPS at MAMI Zoe Marinides The aim of the research project is to determine the neutron detection efficiency of the Crystal Ball and Two Armed Photon Spectrometer (TAPS) detector system used in the A2 collaboration at MAMI, at the University of Johannes Guttenberg in Mainz, Germany. A photon beam of energies up to 1.5 GeV is used to investigate photodisintegration and photo-production processes from a deuterium target. By looking at both the breakup of the deuteron into the proton and neutron, as well as coherent $\pi ^{0 }$production, the efficiency of neutron detection can be determined at a range of energies. The results of the efficiency measurements are essential in determining cross sections for future experiments as well as in testing the accuracy of simulations for channels such as double $\pi ^{0 }$and $\pi ^{0}\eta $ production on the neutron. [Preview Abstract] |
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GB.00074: Low-Background Counting at Homestake Iseley Marshall Background characterization at Homestake is an ongoing project crucial to the experiments located there. From neutrino physics to WIMP detection, low-background materials and their screening require highly sensitive detectors. Naturally, shielding is needed to lower ``noise'' in these detectors. Because of its vast depth, Homestake will be effective in shielding against cosmic-ray radiation. This means little, however, if radiation from materials used still interferes. Specifically, our group is working on designing the first low-background counting facility at the Homestake mine. Using a high-purity germanium crystal detector from ORTEC, measurements will be taken within a shield that is made to specifically account for radiation underground and fits the detector. Currently, in the design, there is a layer of copper surrounded by an intricate stainless steel casing, which will be manufactured air tight to accommodate for nitrogen purging. Lead will surround the stainless steel shell to further absorb gamma rays. A mobile lift system has been designed for easy access to the detector. In the future, this project will include multiple testing stations located in the famous Davis Cavern where future experiments will have the ability to use the site as an efficient and accurate counting facility for their needs (such as measuring radioactive isotopes in materials). Overall, this detector (and its shield system) is the beginning of a central testing facility that will serve Homestake's scientific community. [Preview Abstract] |
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GB.00075: Development of an Automated Target Oscillator For Use in Reaction Studies William Martin, D.W. Bardayan, K.L. Jones, J.A. Cizewski When a high current (greater than 10$^6$ particles per second) of heavy ion beam bombards a plastic target, the energy deposition and heat buildup can cause target degradation. In the case of calibration/pilot beams used on thin (100-250$\mu$g/cm2) deuterated polyethylene targets, even a short exposure has been found to result in damages such as cracking, burn through, and target carbonization/oxidation. One way to reduce the deleterious effects of this accumulated energy is to oscillate the target, thereby spreading the deposited energy over a larger area and allowing for an increased rate of heat dissipation. At the HRIBF in Oak Ridge, an automated target oscillation system has been developed using an electronic stepper motor and a control unit equipped with a custom Field Programmable Gated Array (FPGA) circuit board. Taking into consideration varying target sizes and beam densities, the algorithm loaded onto the FPGA allows the user to adjust both the frequency and amplitude of oscillation. Conclusive testing shows that incorporation of the target oscillator apparatus introduces no detectable electromagnetic noise to the detector array. Live beam testing is planned in the near future, and it is anticipated that the target oscillator will greatly assist HRIBF's efforts to maintain target integrity during calibration and experiments. [Preview Abstract] |
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GB.00076: Combining the Statistical and Meson Cloud models of the Proton Tyler Matossian The meson cloud model of [1] of the proton is extended to include the statistical model of [2] to study the $\overline {d},\ \overline{u}$ \ asymmetry in the population of sea quarks in the proton. The meson cloud model represents the proton in terms of non-perturbative fluctuations into meson-baryon pairs. The statistical model has the proton built up of states which include valence quarks, gluons, and sea quarks, connected in detailed balance through perturbative quark-gluon processes. Although both models provide good agreement with the E866 measurements of $\overline{d}(x)-\overline{u}(x)$, they fail to agree with the $\overline{d}(x)/\overline{u}(x)$ distribution. In our hybrid model, parton distributions calculated in the statistical model are used for the meson and baryon terms in the meson cloud model. Results will be compared to the E866 experiment.\\[4pt] [1] J.~Speth and A.~W.~Thomas, Adv.\ Nucl.\ Phys.\ 24 (1997) 83 \\[0pt] [2] Y-J. Zhang et al, Phys. Lett. B 523 (2001) 260; Y-J. Zhang et al., Phys. Lett. B 528 (2002) 228 [Preview Abstract] |
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GB.00077: A windowless He-gas target for astrophysics experiments Sayaka Matsuda, Kenshi Sagara, Takashi Teranishi, Kunihiro Fujita, Rie Iwabuchi, Masahiko Taniguchi, Takashi Gotoh, Keizyu Nakano, Nozomi Oba, Hiroyuki Yamaguchi In He-burning in stars $^{4}$He($^{12}$C,$^{16}$O)$\gamma $ reaction plays an important role, however, the reaction cross section at stellar energy has not been measured yet. This experiment is very difficult. To measure the $^{4}$He($^{12}$C,$^{16}$O)$\gamma $ cross section, a thick (24Torr x 3cm) windowless $^{4}$He gas target has been developed at Kyushu University. Structure of the windowless gas target and measurement of the target thickness using a proton beam will be reported. [Preview Abstract] |
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GB.00078: Commissioning and Calibrating Bucking Coil System for HKS Water Cerenkov Detector Victor Maxwell, Joerg Reinhold Experiment E05-115, in Hall C at Jefferson Lab (JLab), will perform a spectroscopic study of lambda hypernuclei for a wide mass region using the ($\it{e, e' K^+}$) reaction. Accurate detection of coincident kaons and electrons guarantees that a lambda hyperon has been produced within the nucleus. The High Resolution Kaon Spectrometer, whose instrumentation is composed of, among other devices, a water Cerenkov detector (WC), will be employed towards this end. The detector use a series of photomultiplier tubes (PMT) to generate signals associated with particular events. This research focuses on studying the effects of external magnetic fields on the collection efficiency of the PMT. Upon introducing an external magnetic field near the PMT, the observed single photo-electron (SPE) emission rate decreases. Magnetic fields of equal strength and opposite orientation to the external field are created by applying current to bucking coils (BC) placed around the individual PMT. Data indicates a relationship between SPE emission rates, and collection efficiency distributions. Upon being placed in Hall C, this relationship is used to set the appropriate current for each BC. The correct calibration of the PMT yields a large collection efficiency, thereby allowing particles detected by the WC to be categorized accurately and smooth operation of experiment E05-115. [Preview Abstract] |
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GB.00079: Open quantum systems David Mayett I analyzed a particular quantum system, which I called cross array. At first, I analyzed the stationary states and energies of specific cases: the system was closed and the number of cells per branch was N=1 and N=2. Consequently, I generalized the case for an arbitrary number of cells per branch. In doing so, I was then able to study cases where some channels were open to the continuum. The properties of these open quantum systems were described by the use of discretized effective non-hermitian Hamiltonian. I studied a keen transition between the weak and strong coupling regimes. The weak coupling limit produced well- the decay widths were collected and Dicke states were formed. [Preview Abstract] |
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GB.00080: Transformation of SO(5) coupling coefficients to the isospin basis A.E. McCoy, M.A. Caprio The SO(5) pairing model for nuclei with N$\approx$Z is based on the algebra of the proton and neutron pair creation, pair annihilation, and isospin operators. Nuclear structure calculations carried out in this framework require the coupling coefficients for SO(5), reduced with respect to the physical isospin subalgebra. However, it is more straightforward to calculate coupling coefficients reduced with respect to the mathematically natural (canonical) SO(4) subalgebra. We transform the canonical chain coupling coefficients to the physically relevant isospin chain by a unitary transformation obtained by diagonalizing the isospin operator in the canonical basis. Supported by the US NSF under grant NSF-PHY05-52843 and the US DOE under grant DE-FG02-95ER-40934. [Preview Abstract] |
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GB.00081: Simulations for Silicon Strip Detector Calibration and Code Comparison Zachary Meisel For studies of beta-delayed proton emission of rare isotopes in the astrophysical rapid proton capture process, accurately calibrated detection devices are vital. Simulations are necessary to interpret the signals from various calibration sources and methods, and to analyze experimental data from beta-delayed proton emission. Here both the MCNPX (Monte Carlo N-Particle transport) and GEANT4 (GEometry ANd Tracking) simulators have been used in conjunction with experimental data from calibration sources to energy calibrate three double-sided silicon strip detectors (DSSDs). This study includes the analysis of various systematic effects, such as detector geometry, source energy, source position, and particle number, with a particular emphasis on their relation to energy deposition spectra. Possible explanations for discrepancies between each code and the data will be given. The results of these simulations will be used in the study of the beta-delayed proton emission of $^{69}$Kr at the National Superconducting Cyclotron Laboratory at Michigan State University. [Preview Abstract] |
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GB.00082: Helium 3 neutron precision polarimetry Christopher Menard Measuring neutron polarization to a high degree of precision is critical for the next generation of neutron decay correlation experiments. Polarized neutrons are also used in experiments to probe the hadronic weak interaction which contributes a small portion ($\sim$10-7) of the force between nucleons. Using a beam of cold neutrons at Los Alamos Neutron Science Center (LANSCE), we polarized neutrons and measured their absolute polarization to $\sim$0.1\%. Neutrons were polarized by passing them through a $^3$He spin filter, relying on the maximally spin dependent 3He neutron absorption cross section. The neutron polarization can be determined by measuring the wavelength-dependent neutron transmission through the $^3$He cell. An independent measurement of the neutron polarization was also obtained by passing the polarized beam through an RF spin flipper and a second polarized $^3$He cell, used as an analyzer. To measure the efficiency of the spin flipper, the same measurements were made after reversing the $^3$He polarization in the polarizer by using NMR techniques (adiabatic fast passage). We will show the consistency of these two measurements and the resulting precision of neutron polarimetry using these techniques. [Preview Abstract] |
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GB.00083: Neutron Capture Rates in R-Process Nucleosynthesis at Hot Outflows From Black Hole -- Neutron Star Merge Ana Paola Mikler, Rebecca Surman Simulations of $r$-process, or rapid neutron capture, nucleosynthesis require nuclear data such as masses, beta decay rates, and neutron capture rates for thousands of nuclei far from stability. While the influence of nuclear masses and beta decay rates on the $r$ process has been well studied, neutron capture rates have received less attention. Furthermore most of the existing studies on the influence of neutron capture rates on the $r$ process focus on a particular astrophysical site: the core-collapse supernova. Here we examine the effects of individual neutron capture rates on an $r$ process in an alternate environment -- hot outflows from black hole-neutron star mergers. We focus on nuclei in the $A \sim$ 130 $r$-process abundance peak and consider outflow trajectories that produce either a weak $r$ process or a main $r$ process. We identify the nuclei whose capture rates affect the largest changes to the resulting abundance pattern and describe the mechanisms by which such changes occur. [Preview Abstract] |
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GB.00084: The Fermilab E-906 Drell-Yan Experiment Benjamin Miller Fermilab E-906 will use the Drell-Yan process to improve our knowledge of the structure of the nucleon. This experiment will determine the anti-down to anti-up quark asymmetry to a much larger Bjorken-x than was attained by its predecessor, E- 866/NuSea. At its highest x measurements, E-866/NuSea hints at very interesting behavior for this ratio. E-906 will extend the light anti-quark asymmetry to x $\sim$ 0.5. In addition, E-906 will use nuclear targets to measure partonic energy loss in cold nuclear matter and study anti-shadowing. E-906 will use the Fermilab 120 GeV/c Main Injector to collide protons with targets of liquid hydrogen, liquid deuterium and solid nuclear targets. The detector under construction is a two-magnet, focusing spectrometer consisting of four detector stations, similar to the E866/NuSea spectrometer. A fast level one trigger will come from eight hodoscope planes. Wire and drift chambers will be used to reconstruct particle trajectories to separate events originating in the target from those originating from the internal beam dump. [Preview Abstract] |
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GB.00085: Design and Automation of an Induced Depletion Experiment on $^{108m}$Ag I.N. Mills, G.P. Trees, C.J. Sweeney, T.A. Balint, S.A. Karamian, J.J. Carroll Nuclear isomers may be able to store and provide energy for certain applications. To determine if a particular nuclear isomer is a good candidate for such an application, an experiment must demonstrate an induced depletion. This depletion would bypass the slow decay transitions of the metastable state by exciting the nucleus into a shorter-lived, higher-energy intermediate states with a decay branch that leads to the ground state. An experiment is being conducted at Youngstown State University's X-ray Effects Laboratory as part of the Isomer Physics Project which has been custom designed to test induced depletion of $^{108m}$Ag by bremsstrahlung. The poster will cover the design of the experiment, the use and development of an automated control and DAQ system, and initial results. [Preview Abstract] |
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GB.00086: Simulating the Neutron Detection of the CLAS12 Detector Mark Moog, Gerard Gilfoyle, Matt King We have studied the expected performance of the CLAS12 detector that will be built at Jefferson Lab as part of the 12-GeV Upgrade. The Upgrade hopes to further our understanding of the internal structure of nucleons by studying nucleon properties such as form factors and generalized parton distributions. The CLAS12 detector will consist of drift chambers, scintillators, Cherenkov counters, calorimeters, and a vertex finder. The initial round of experiments for the 12-GeV upgrade include ones that require neutron detection and we are studying the neutron detection efficiency in preparation for such experiments. To study CLAS12's performance we generated the four-momenta of an electron and neutron after a relativistic, elastic collision and passed these data into the GEANT4-based program gemc. The code uses the four-momenta of these particles and simulates their interaction with the components of the detector. Reconstruction of the events was done with the program Socrat. By comparing the number of reconstructed neutron events to the number of thrown neutron events we extracted the efficiency of the outer time-of-flight scintillators. A precise knowledge of the neutron detection efficiency is required to keep systematic uncertainty low in future experiments. [Preview Abstract] |
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GB.00087: Fluorescence Efficiency of Tetra-Phenyl-Butadiene D.A Moore, J. Maassen, V.M. Gehman, S. Seibert, A. Hime, K. Rielage, D. Mei, Y. Sun Tetra-Phenyl-Butadiene (TPB), a known organic wavelength shifter, converts UV scintillation light into visible light detectable by Photomultiplier Tubes (PMTs). Experiments based in liquid argon, such as CLEAN and DEAP require TPB to correct for the sensitivity of the PMTs. The primary objective of these experiments is detecting WIMPs (Weakly Interacting Massive Particles) that may compose the dark matter in the Universe. We systematically investigated the effects of different wavelengths on TPB-coated acrylic disks using a deuterium lamp as a source of UV light, a monochromator, and a calibrated photodiode detector. We tested a variety of thicknesses of TPB on acrylic disks and blank disks to analyze the spectra and shed new light on several properties and attributes of TPB. We examined the emission spectrum of TPB and evaluated the conversion efficiency (photons out / photons in) in order to broaden the knowledge of how to optimize the visible light collection on the PMTs, while aiding in several modeling processes. I will present our findings on the efficiency and spectral emission of TPB, along with images of the actual setup, as well as possible future research. [Preview Abstract] |
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GB.00088: Simulations to Understand the Calibration of the PHENIX Muon Piston Calorimter Steven Motschwiller In 2007, the Relativistic Heavy Ion Collider (RHIC) generated $sqrt{s_{NN}}$ = 200 GeV Au + Au collisions. The PHENIX Muon Piston Calorimeter will allow a measurement of transverse energy in the forward/backward region (3.1$<|\eta|<$3.8) but first the detector must be calibrated in this high occupancy environment. In order to understand the steps that must be taken with the real data, a simulated set of $\pi^{0}$s were generated and allowed to decay. Same event photon pairs and mixed event photon pairs were used to generate histograms with signals plus combinatoric background, and histograms with only combinatoric background. Normalization of the background histogram and subtraction from the histogram with the signal recovered the original sample of pions. Having accomplished this, identical steps were performed on the real data. [Preview Abstract] |
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GB.00089: The design and commissioning of a polarized helium-3 test stand Timothy Nichols, Damon T. Spayde Many experiments, such as the neutron electric dipole moment (nEDM) experiment, are interested in achieving high degrees of polarization and long relaxation times in helium-3 in order to complete their measurements. It is possible to add another degree of sensitivity to the aforementioned experiment by using a technique known as spin dressing. In this technique the polarized helium-3 sample is placed into a large uniform magnetic field, known as the holding field. A radio frequency (RF) field is then applied transverse to the holding field altering the effective gyromagnetic ratio and creating the spin dressing effect. In this paper we present the design, construction progress, and calibration results of a test stand using metastability exchange optical pumping to polarize samples of gaseous helium-3. The goal of this test stand is to address the question of what happens to the nuclear polarization and relaxation time of helium-3 when the spin dressing field is not spatially uniform. [Preview Abstract] |
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GB.00090: D$_{s}$ Meson Reconstruction from STAR Heavy Flavor Tracker Oumarou Njoya Nucleus-Nucleus Collisions at RHIC (the Relativistic Heavy Ion Collider) have produced a strongly interacting dense partonic matter whose degrees of freedom are governed by the Quantum ChromoDynamics (QCD). The Solenoid Tracker At RHIC (STAR) is an ongoing major experiment which aims to study the properties of the QCD matter under extreme energy density, pressure, and temperature. Heavy quark production and propagation are unique probes to the dense matter created at RHIC. The HFT (Heavy Flavor Tracker) is a proposed detector upgrade of STAR, capable of reconstructing open charm hadrons from hadronic decay channels. We carry out a study of D$_{s}$ meson reconstruction using GEANT simulations. We reconstruct D$_{s}$ mesons through a 3-body decay of K$^{+}$K$^{-}\pi $ at displaced vertices as a function of transverse momentum. We present preliminary results on the statistical significance of the reconstructed D$_{s}$ signal as well as on the D$_{s}$ detection efficiency using HFT. The physics impact of the D$_{s}$ measurement will also be discussed. [Preview Abstract] |
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GB.00091: Observation of neutron-unbound resonant states in 23O and 28Ne John Novak, Steve Quinn, Michael Strongman, Shea Mosby, Artemis Spyrou, Thomas Baumann, Michael Thoennessen The decay energy spectra of neutron-rich 23O and 28Ne were measured. The isotopes were produced in stripping reactions from a 85MeV/u 29Na beam on a beryllium target. Neutrons were measured in coincidence with light neutron-rich fragments produced in stripping reactions from an 85MeV/u 29Na beam on a beryllium target. The neutrons were detected with the Modular Neutron Array (MoNA) and the fragments were analyzed with the MSU/FSU Sweeper magnet system. Low-energy resonances close to the neutron-separation energies were observed in both system. The results for 23O agrees with a previous measurement\footnote{A. Schiller et al., Phys. Rev. Lett. 99 (2007) 112501} and the resonance in 28Ne was observed for the first time. [Preview Abstract] |
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GB.00092: Structure of $^{206}$Radium Paul Orland, A. Schmidt, A. Heinz, R. Winkler, J. Qian, T. Ahn, R. Casperson, G. Ilie, D. McCarthy, J.R. Terry, V. Werner, E. Williams Various radium isotopes have been investigated in the past in order to study the onset of collectivity below N=126. Here we present results of an investigation of $^{206}$Ra which has six protons above the Z=82 shell closure and eight neutron holes in the N=126 neutron shell closure. Though experiments on $^{206}$Ra have previously been performed, this is the first time prompt gamma ray transitions have been measured. Using the technique of recoil decay tagging at the gas-filled Small Angle Separator System at Yale for Evaporation Residues (SASSYER), $^{206}$Ra and other isotopes were identified at the focal plane and correlated to their prompt gamma rays detected at the target position. A comparison of $^{206}$Ra with neighboring isotopes, especially with respect to trends in collectivity, is presented. [Preview Abstract] |
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GB.00093: One Proton Knockout from $^{83}$As J.L. Palardy, B.A. Hartl, L.A. Riley, T.R. Baugher, D. Bazin, A. Gade, T. Glasmacher, G.F. Grinyer, S. McDaniel, R.T. Meharchand , A. Ratkiewicz , K.A. Walsh, D. Weisshaar We present a one-proton knockout measurement from the $N=50$ nucleus $^{83}$As, conducted at the National Superconducting Cyclotron Laboratory at Michigan State University (NSCL). A cocktail beam composed primarily of $^{82}$Ge (56\%) and $^{83}$As (35\%) was produced through fragmentation of a $^{86}$Kr beam incident on a $^9$Be primary target. Incoming beam particles are identified by time of flight, and reaction products are identified with the S800 Magnetic Spectrograph. Gamma rays from the beam-like reaction products were captured by the Segmented Germanium Array (SeGA). Preliminary results will be discussed. [Preview Abstract] |
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GB.00094: Performance of a 2m prototype neutron detector for VANDLE Casey Pangan, J.C. Blackmon, L.E. Linhardt, M.M. White, J.A. Cizewski, P. O'Malley, W.A. Peters, D.W. Bardayan, R. Grzywacz, M. Madurga, S. Paulauskas, C. Matei, B.C. Rasco, F. Raiola, F. Sarazin VANDLE (Versatile Array for Neutron Detection at Low Energies) is an array of plastic scintillator detectors that is being developed for measurements with radioactive ion beams. The array will consist of over 200 scintillator elements in two different shapes that can be configured in a variety of geometries to achieve efficient neutron detection with good time-of-flight for different types of measurements. We have constructed a 2 meter long prototype detector element for VANDLE and characterized its performance through a variety of measurements using cosmic rays, neutron and gamma sources. The position resolution, time resolution, light output, efficiency, and neutron-gamma discrimination by time-of-flight have all been studied. Results from these tests will be presented. Plans for a test measurement of the (d,n) reaction using a number of these detector elements will also be discussed. [Preview Abstract] |
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GB.00095: Instillation of Resistive Plate Chambers for the PHENIX Detector Langston Parks The muon trigger upgrade for Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) will allow for faster and more accurate studying of flavor separated quark and anti-quark spin polarizations in the proton. One way to measure these polarizations is through the analysis of single spin asymmetries for $W-$boson production in proton-proton collisions. PHENIX is capable of measuring high momentum muons at forward rapidity, however the current trigger is not capable of separating leptons from W-decay. The goal of the upgrade is to improve the ability of the Relativistic Heavy Ion Collider (RHIC) to collect and analyze muons that decay from W-bosons produced in polarized proton-proton collisions. To achieve this goal Resistive Plate Chambers (RPCs) will be installed at the PHENIX detector located at RHIC along with new front-end electronics. This poster will discuss the installation of the RPCs. [Preview Abstract] |
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GB.00096: Gamma Ray Spectroscopy and SASSYER Benjamin Pauerstein, Cain Bonniwell, J.M. Allmond, C.W. Beausang An experiment was performed to study the Gd and Tb nuclei resulting from a 27 MeV proton beam on a 156Gd target. This was conducted at Lawrence Berkeley National Laboratory using the STARS/LIBERACE array. The main focus of the experiment was on charged particle channels (p,d) into 155Gd and (p,t) into 154Gd. However, the trigger was either gamma-gamma or particle-gamma so new data was also obtained on 155Tb nuclei following fusion evaporation reactions. Preliminary analysis was conducted at Wright Nuclear Structure Lab where RADWARE programs were used to analyze the data and search for unknown gamma rays. A second, separate, experiment was conducted using the SASSYER (a gas-filled separator at Yale). In this experiment, fission fragments from a 252Cf source were focused to a DSSD and a Ge detector was used to search for either gamma-decay from long lived isomers in the fission fragments or to find gammas from recoil-beta-decay tagging on the fission fragments. The data collection seems to have gone smoothly, and the data is currently being sorted for analysis. This work was supported by the US Department of Energy under grant numbers DE-FG02-52NA26206 and DE-FG02-05ER41379. [Preview Abstract] |
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GB.00097: The R-process, nucleosynthesis, and new nuclear masses Nancy Paul Precise, accurate measurements of nuclear masses are crucial for astrophysical modeling, reproducing the observed solar abundances of the elements, and for disentangling the nuclear physics imprinted on those abundances. More generally, masses are necessary for understanding nucleosynthesis via the r-process, thought to be responsible for over 50\% of the elements heavier than Iron. The advent of ion traps and storage rings has generated a profusion of very precise measurements since the 2003 Atomic Mass Evaluation. I compiled an up-to-date list of new measurements from labs worldwide and incorporated them into Bradley Meyer's (Clemson University) classical model of the r-process to examine the impact of the new measurements. Sensitivity studies of various theoretical mass models and the new measurements in the r-process code, showed the largest deviations in the $A=70-85$ mass region. These studies will be used to plan new measurements of nuclei along the r-process path, near $^{78}$Ni. [Preview Abstract] |
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GB.00098: NIFFTE TPC Experiment: Slow Controls Nathan Pickle The Time Projection Chamber (TPC) experiment conducted by the Neutron-Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration will allow for unprecedented precision in observing neutron-induced fission events. Previous fission detectors only registered quantity and magnitude of events; the TPC will be capable of reconstructing a track for each fragment that is detected. Developing a better understanding of fission events will allow for the design of nuclear reactors that are more efficient and produce minimal waste. The slow controls portion of the data acquisition (DAQ) system for this experiment will set and monitor high and low voltages, as well as make measurements of temperature, barometric pressure, humidity, and other factors that might affect experimental results. The Maximum Integration Data Acquisition System (MIDAS) framework software will be used as the basis of the slow controls DAQ system. IOtech DaqScan/2001 hardware will be used with DBK50 and DBK51 modules to monitor voltages, and DBK90 modules to record temperature. Support for other hardware modules may be added in the future. The presented work includes device driver development and DAQ system construction. [Preview Abstract] |
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GB.00099: Using Support Vector Machines for $D^0$ Reconstruction in STAR Simulations Bijan Pourhamzeh The STAR Collaboration proposes to construct a microvertex detector, called the Heavy Flavor Tracker (HFT), using components made up of active pixel sensors and silicon strips to study the quark-gluon plasma (QGP). The HFT is designed to measure heavy mesons containing $c$ and $b$ quarks, such as the $D^0$ meson. These heavy quarks are an ideal probe to study the QGP. Support Vector Machines (SVMs), which are a set of kernel- based learning methods used for classification and regression, provide one candidate method for $D^0$ reconstruction in the HFT. Given two sets of training data, viewed as vectors in an $n$-dimensional space, the SVM will construct an $(n-1)$- dimensional hyperplane which maximizes the separation between the data, while minimizing misclassification error. Using the hadronic decay channel, $D^0 \rightarrow K^- + \pi^+$, our preliminary results show that with a Radial Basis Function (RBF) kernel, $K(x,z)=\exp{(-\gamma\|x-z\|^2)}$, SVMs can correctly classify pion-kaon pairs with a very high success rate. We compare the performance of SVM reconstruction with the currently implemeted reconstruction method, and determine which yields a greater signal significance, $\frac{S}{\sqrt{S+B}}$, per $p_T$ bin. [Preview Abstract] |
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GB.00100: Non-Resonant Neutron Emission of Excited Neutron-Rich Nuclei Stephen Quinn, John Novak, Michael Strongman, Shea Mosby, Artemis Spyrou, Thomas Baumann, Michael Thoennessen Neutron-decay spectroscopy of neutron-unbound states at and beyond the dripline rely on the correct description of non- resonant events underlying the resonance states. In order to understand the origin of these events, decay energy spectra of isotopes with no apparent resonances were analyzed. Neutrons were measured in coincidence with light neutron-rich fragments produced in stripping reactions from an 85MeV/u 29Na beam on a beryllium target. The neutrons were detected with the Modular Neutron Array (MoNA) and the fragments were analyzed with the MSU/FSU Sweeper magnet system. The decay energy spectra of the isotopes 18N, 19N, 20N, 21O, 22O, 23F, 24F, 26Ne, and 27Ne were analyzed. No evidence for an isotope dependence was observed. However, the spectral shape exhibited differences as a function of element. The description of the data using a thermal emission model will be presented. [Preview Abstract] |
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GB.00101: Effects of Fluctuations and Inhomogeneities on Jet quenching in High Energy Nuclear Collisions Enrique Ramirez-Homs, R.J. Fries, R. Rodriguez In a quark-gluon plasma with color degrees of freedom, jets of energetic partons interact and lose energy. They can thus be used to probe its properties. Here we study how fluctuations in the energy density within the plasma affect this process. The goal is to determine the size of the fluctuations required to have an observable effect on the nuclear modification factor and elliptic flow of pions. [Preview Abstract] |
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GB.00102: Hydrogen Outgassing in Stainless Steel Gun Chambers Melissa Ricketts Vacuum quality is an important aspect in electron guns. The hydrogen outgassing rate is a determinant of the vacuum quality in stainless steel gun chambers. A low outgassing rate allows for a better vacuum and therefore a longer photocathode lifetime. Low outgassing rates depend on thermal treatments of the chamber. The purpose of this project is to put together a gun chamber, and assess the hydrogen outgassing rate after an administered thermal treatment. To determine the hydrogen outgassing rate, pressure measurements of the vacuum chamber must be taken. Once these measurements have been obtained, they can be used along with the known volume and surface area of the chamber to calculate the outgassing rate. A thermal treatment of 400 \r{ }C for nine days achieved an outgassing rate of 1.12 x 10$^{-13}$ Torr L /s cm$^{2}$. The value obtained for the hydrogen outgassing rate is one order of magnitude better than previous outgassing rates. This is because in the past, this specific thermal treatment has never been used. This improvement illustrates the success of the project. [Preview Abstract] |
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GB.00103: Accurate Position Calibrations for Charged Fragments Autumn Russell, Joseph E. Finck, Artemis Spyrou, Michael Thoennessen The Modular Neutron Array (MoNA), located at the National Superconducting Laboratory at Michigan State University, is used in conjunction with the MSU/FSU Sweeper Magnet to study the breakup of neutron-rich nuclei. Fragmentation reactions create particle-unstable nuclei near the neutron dripline which spontaneously break up by the decay of one or two neutrons with energies that reflect the nuclear structure of unbound excited and ground states. The neutrons continue forward into MoNA where their position and time of flight are recorded, and the charged fragments' position and energy are measured by an array of detectors following the Sweeper Magnet. In such experiments the identification of the fragment of interest is done through energy loss and time-of-flight measurements using plastic scintillators. The emitted angles of the fragments are determined with the use of CRDCs. The purpose of the present work was the calibration of the CRDCs in the X and Y axis (where Z is the beam axis) using specially designed masks. This calibration was also used for the correction of the signal of the plastic scintillators, which is position dependent. The results of this work are used for the determination of the ground state of the neutron-unbound $^{24}$N. [Preview Abstract] |
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GB.00104: Geant Simulation of Cosmic Ray Veto System Matthew Russell The double-beta decay processes can provide essential details on the interactions of neutrinos, and many experiments are underway that may be able to detect the highly sought neutrinoless double-beta decay channel. This decay can provide a measurement of the absolute mass scale of neutrinos, but only if the Nuclear Matrix Elements (NME) of the candidate nuclei are known to high precision. Predictions for the NMEs of one of the most heavily studied candidates,$^{76}$Ge, vary by at least 50\% and need to be further investigated. The University of Notre Dame Nuclear Structure Lab is in a unique position to probe the pairing structure of nucleons in $^{76}$Ge via a two-proton transfer reaction. A time of flight measurement identifies neutrons from the $^{76}$Ge($^{3}$He,n) reaction using a large acceptance neutron detector. The cosmic ray background in our detector is large compared to the neutron signal, making it necessary to construct a plastic scintillator veto counter. At least an 80\% rejection of background is necessary to cut the fractional error in half. A Geant simulation of the veto plastic is necessary in understanding the expected vetoed background signal in our detector and optimizing the rejection system. This project will report on the energy spectrum our Geant simulation predicts from the scintillator, as well as the accuracy of our model compared to the actual energy spectrum taken from our scintillator. The data's relevance to the veto system and error analysis will be discussed. [Preview Abstract] |
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GB.00105: Systematic Error Studies for a Measurement of the Beta Asymmetry Parameter Using Ultracold Neutrons Rebecca Russell The angular correlation between a neutron's spin and the initial direction of its emitted electron when undergoing beta decay is known as the beta asymmetry parameter. This parameter can be used to help search for physics beyond the Standard Model by determining the value of the up and down quark weak mixing angle and testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix. The UCNA experiment at the Los Alamos Neutron Science Center seeks to obtain a precise measurement of the neutron beta asymmetry by studying the beta decay of a dense population of identically-polarized ultracold neutrons (UCN.) The UCN are produced in a solid deuterium source and are polarized by a static magnetic field. Electrons emitted from the beta decay of UCN travel outwards along solenoidal field lines towards one of two oppositely-placed units each made up of a multi-wire proportional chamber backed by a plastic scintillator detector. Accurate determination of the events in these detection units is essential to a high-quality measurement of the expected directional asymmetry. The results of systematic error studies of recent UCNA data are presented. [Preview Abstract] |
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GB.00106: Optimal Seeding of Multiprong Reconstruction of the NovA Prototype Detector Donovan Ruth, Mark Messier NOvA is a research project based at Fermilab that will search for neutrino oscillations in the NuMI muon neutrino beam. The near (at Fermilab) and far (Ash River, MN) detectors are arrays of tubes filled with liquid scintillator oriented alternatively horizontally, and vertically. When a neutrino interacts with a nucleus in the detector, the outgoing charged particles cause the liquid scintillator to ionize and emit visible light which is collected by optical fibers for detection. We can determine the magnitude of charge and position of these particles based on the intensity and pattern of the light given off from the liquid scintillator. A computer program reads the data from every tube, and attempts to reconstruct a vertex where the interaction occurred, and ``prongs'' or paths in which these particles have travelled by taking data of an event from the detector and seeding a vertex and one prong. Then using a fitter, finds the best fit path for some vertex and the prong, determines if this fit is ``good enough'' using certain scoring methods and loops through this process using one more prong each time to make a final placement of the vertex and prongs as the best fit to the event. Using simulated events, we have tested several seeding methods for the vertex of this program and determined the most accurate among them. We are currently testing a method to directionally seed these prongs, and have made several other observations of the fitter. [Preview Abstract] |
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GB.00107: Decay Detector For The Study of Isoscalar Giant Monopole Resonances Caleigh Samuels, Dave Youngblood, Yiu-Wing Lui, Jonathan Button The nuclear matter incompressibility is extracted from measurement of the energy of giant monopole resonances. This incompressibility term is incorporated in the nuclear matter equation of state, which can be used to physically describe supernovae and neutron stars. Progress has been made in the design, construction, and calibration of a decay particle detector mainly composed of plastic scintillator arrays, which we will use to study the Isoscalar Giant Monopole Resonance (ISGMR) in unstable nuclei. Nuclei excited to the ISGMR region are particle unstable and will p, alpha, or n decay shortly after excitation in light nuclei. We explore two method for predicting the light output by the scintillators of the detector due to energy loss by light ions. [Preview Abstract] |
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GB.00108: Polarization Correlations of Entangled Photon Pairs from Positronium Decay as a Test of Bell's Inequality Minoru Sanda, Motonobu Takaki It is well known that Einstein, Podolsky, and Rosen (EPR) claimed that quantum mechanics might be incomplete in terms of local realism. Bell showed that experimental verification of local hidden variable theories is possible by comparing with the Bell's inequality. We measured polarization correlations $\langle A B \rangle$ of two photons produced by positoronium decay. Here $A$ and $B$ are the polarizations of photons. The value $\langle A B \rangle$ can be expressed as $-\kappa\cos(2\phi) $ where $\phi$ is the angle between the axes of two photon polarizations. The Bell's inequality gives $\kappa \leq \frac{1}{\sqrt{2}}$ in local realism, whereas non-local quantum mechanics gives $\kappa=1$ which disagrees with local hidden variable predictions. We have constructed two sets of Compton polarimeters, each of which consists of a liquid scintillator and four {\rm NaI} scintillators. The photon polarization can be deduced from the azimuthal distribution of Compton scattering. The experimental data was combined in order to reduce experimental false polarizations, and thus we have succeeded to deduce $\langle A B \rangle$ with high accuracy. Our preliminary result is $\kappa=1.0$. This result is consistent with the prediction based on non-local quantum mechanics, and violates the Bell's inequality. In the meeting, we will report final results for $\langle A B \rangle$. Furthermore, we will compare our results with theoretical predictions. [Preview Abstract] |
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GB.00109: Developments of Hadron Blind Detector for $\phi \to $ e$^{+ }$e$^{- }$measurements at J-PARC Tamotsu Sato We are proposing a new experiment at J-PARK to measure mass modifications of $\phi$ meson in nucleus using $\phi \quad \to $ e$^{+}$e$^{-}$ decays. In the experiment, a Hadron Blind Detector (HBD) is proposed for the electron identification. The HBD is originally developed for the PHENIX experiment at BNL and modified for the experiment. Current design has a 50cm Cerenkov radiator operated with pure CF$_{4}$ directory coupled to a 3layers-GEM detector with CsI photocathode and a pad-readout is used. CsI is directory evaporated on the top of GEM foil and used as a photocathode. In our case, the GEM foil has 100$\mu $m thickness and this is a highly new feature done by our group. The main advantage of this scheme is that 100$\mu $m thickness GEM has larger effective gain than 50$\mu$m thickness GEM. By virtue of this, photoelectrons from Cerenkov radiation to be amplified higher by the first photocathode-GEM foil. Thus, we carry out a stable operation. We measured the quantum efficiency of CsI photocathode GEM in pure CF$_{4}$ and a test experiment using electron-beam at LNS GeV-$\gamma $ beam-line at Tohoku University is done to evaluate performance of the HBD. As a result of the test, we succeeded in detecting Cerenkov radiation using the HBD. [Preview Abstract] |
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GB.00110: A Signature of New Physics: Determining Missing Energy in the ATLAS Detector Thomas Schmit, Vivek Jain, Daria Zieminska Missing energy is a major discriminant for new physics in high energy proton-proton collisions generated by the Large Hadron Collider at CERN. The ATLAS detector, which collects data at the LHC, has a very sophisticated calorimeter that measures the energy and position of particles and jets created in these collisions. A vector sum of the energy of these objects is performed over the entire detector; a non-zero value implies missing energy. When missing energy is large it indicates that a non-interacting particle may have passed through the detector. Accurate reconstruction of missing energy is necessary to identify new particles, such as candidates for dark matter, e.g., the Lightest Super-symmetric Particle. The focus of this survey was on the accuracy of missing energy reconstruction, specifically, on the role of muons that are created in the collisions. [Preview Abstract] |
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GB.00111: Elemental Composition and Concentration of Upstate New York Rainwater Samples Using the Union College Pelletron Particle Accelerator and Proton Induced X-ray Emission (PIXE) Spectroscopy Katie Schuff, Scott LaBrake, Michael Vineyard, Charles Harrington, Colin Gleason A 1-megavolt tandem electrostatic Pelletron particle accelerator housed at Union College was used to measure the elemental composition and concentration of rain water collected in Schenectady, NY in June 2009. A beam of 2.0-MeV protons was directed at an approximately 12-micrometer thin Mylar film substrate onto which 1.0-mL of concentrated rainwater was dried. The interaction of the incident protons with the target material causes inner shell electrons to be ejected and these vacancies are filled through electronic transitions of higher orbital electrons with the production of x-ray photons characteristic of the elemental composition of the target. This is the PIXE Method. Data on the intensity and energy of x-rays were collected using an Amptek silicon drift detector. Spectra of the number of x-rays collected as a function of energy were analyzed and the elemental composition was found to contain Ca, K, S, Cl, Ti, Cr, Fe, Cu, Zn, \& Se(added as an internal standard) with concentrations determined using the analysis package GUPIX. [Preview Abstract] |
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GB.00112: Sensitivity enhancement for the newly commissioned high efficiency CAESAR array via shielding Christopher Segal, Alexandra Gade, Andrew Ratkiewicz, Travis Baugher, Geoffery Grinyer, Dirk Weisshaar, Miguel Bencomo The CAESium iodide ARray (CAESAR) has been constructed at the National Superconducting Cyclotron Laboratory (NSCL) to further probe the structure of nuclei and determine their level of deformation by in-beam gamma-ray spectroscopy. Completed in May 2009 the commissioning experiment of Coulomb excitation (Coulex) in $^{56}$Ni was performed with great success. The commissioning run was quickly followed by a second Coulex experiment in the region of $^{40}$Si with improved shielding against background radiation. The difference in live time, detector efficiency, and detector sensitivity between the two experiments improved noticeably. Quantitative comparisons between the two experiments will provide great insight into the optimization of CAESAR's performance as well as determining if additional shielding will further improve detection efficiency of the array for future experiments. [Preview Abstract] |
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GB.00113: Track Reconstruction Techniques for the NIFFTE Time Projection Chamber Sarvagya Sharma The Time Projection Chamber (TPC), being constructed by the NIFFTE (Neutron Induced Fission Fragment Tracking Experiment) collaboration will be used for high-precision fission cross-section measurements. These measurements will aid in the design of future generation nuclear power plants. The track reconstruction effort has employed various machine-based image processing algorithms, some of which are borrowed from existing high-energy physics experiments. One of the methods investigated, the Hough Transform is a brute force attempt at finding tracks that isolates features in the TPC space by populating histograms. The dimensions of these histograms represent the unknown track parameters. The second, Binary Space Partitioning (BSP), recursively divides the TPC volume until all tracks are segregated. To determine track fit parameters, an iterative Kalman Filter has been implemented that accounts for multiple scattering and kinks in the track. The final tracks obtained from the reconstruction routines are traced back to the origin for vertex reconstruction. Comparing simulated and reconstructed tracks have shown the validity of these track reconstruction methods. This poster shall illustrate these techniques intended for intelligent track finding and track fitting. [Preview Abstract] |
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GB.00114: PMT Linearity Studies for HAPPEX III Aimee Shore, Luis Mercado HAPPEX is an experiment that will run in Hall A at Jefferson Lab in August - October 2009. The experiment will measure the parity violating electron scattering asymmetry with ~3.5 GeV electrons from a liquid proton target at Q2=0.62 GeV. The experiment intends to measure the expected asymmetry of 24 ppm to 1\% uncertainty. This precision measurement of a small quantity requires minimizing and measuring the non-linearities produced by the detectors. [Preview Abstract] |
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GB.00115: Lifetime Measurements of $^{170}$Hf and a test of the Confined Beta Soft Rotor Model M.K. Smith, V. Werner, A. Heinz, J.R. Terry, J. Qian, R. Winkler, R. Casperson, E. Williams, Z. Berant, R. L\"uttke, B. Shoraka, G. Henning Significant deviations from rigid rotor model energy level predictions have been known to occur in rare earth nuclei. Recently, it was shown these deviations may be caused by centrifugal stretching effects within the nucleus [1]. New geometrical models have been proposed that account for centrifugal stretching, such as the confined beta soft model (CBS). We present the results from a high precision lifetime experiment performed with the New Yale Plunger Device at WNSL, Yale University. The ground state band of $^{170}$Hf was measured through the J=12$^+$ level using the Recoil Distance Doppler Shift method. Excited states were populated in the $^{124}$Sn($^{50}$Ti,$\gamma$)$^{170}$Hf fusion evaporation reaction. Using the lifetimes, the B(E2) values and the quadrupole deformation parameter are determined. Centrifugal stretching is observed as an increased deviation in energy at higher spins in 170Hf. These results are compared to theoretical predictions from the CBS rotor model. Supported by grant DE-FG02-91ER40609.\\[4pt] [1] Costin et al, Phys.Rev. C 79, 024307 (2009) [Preview Abstract] |
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GB.00116: Laser energy absorption and ion production in thick and thin targets Thalassa Sodre A fully relativistic model has been developed for the interaction of an intense laser with an overdense plasma. The model is based on conservation laws in one dimension for momentum flux and energy flux across the vacuum-plasma boundary [ M.G. Haines et al. Phys. Rev. Lett. 102, 045008 (2009)] . The main results are (a) that the maximum hot electron temperature scales as $(1 + 2^{1/2} a_0)^{1/2} - 1$ in units of the electron rest mass energy and (b) the light absorption can be 80\%-90\% for intensity $>$ 10$^{19}$ W cm$^{-2}$ This theory has been extended to the case of a thin target, at the rear boundary of which fast electrons can reflux. Momentum and energy flux conservation leads to surface ion acceleration (typically protons in experiments), while refluxing electrons re-entering the front boundary region lead to greatly reduced laser-light absorption. This is relevant to proton driven fast ignition. [Preview Abstract] |
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GB.00117: Time and Position Resolution Studies for the VANDLE Prototype Detectors Irena Spassova, Jolie Cizewski, William Peters, Catalin Matei The Versatile Array of Neutron Detectors at Low Energies (VANDLE) was developed to study the properties of unstable nuclei via (d,n) reactions and beta delayed neutron emission. This array is comprised of individual scintillator bars of two set lengths: 2 m and 60 cm, coupled to photomultiplier tubes (PMTs). The attenuation length of the scintillator bar plays a direct role in the detector efficiency while the position and timing calibrations help pinpoint where an event occurred in the bar. By using different configurations and sources, it was possible to measure the attenuation length and the position and timing resolutions. Experiments have also been performed pertaining to the construction of the detectors and the materials used in coupling the scintillator to the PMT. Such tests will help optimize the performance of the detectors. The experimental results for the prototype detectors will be presented. [Preview Abstract] |
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GB.00118: Measurement of the Target Single-Spin Asymmetry in Quasi-Elastic 3He?(e,e') Jeremy St. John Experiment E05-015 measured the target single spin asymmetry, Ay for the neutron using the inclusive quasi-elastic 3He (e,e') in Hall A at Jefferson Lab with a vertically polarized 3He target at Q2 = 1.0 and 2.3 GeV. Ay is the asymmetry of target spin up versus target spin down, and is sensitive to the two-photon exchange amplitude. For my presentation I will discuss the goals of the experiment, my contributions and, my involvement in creating a new 3He Target lab at Longwood University. [Preview Abstract] |
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GB.00119: Improving the Accuracy of Neutron Multiplicity Counting Scott Stewart Neutron Multiplicity Counting is an assay method used in non-destructive analysis of plutonium for safeguards applications. It is widely used in nuclear material accountancy by international (IAEA) and national inspectors. The method uses the measurement of the correlations in a pulse train to extract information on the spontaneous fission rate in the presence of neutrons from ($\alpha$,n) reactions and induced fission. There is currently interest in improving the accuracy of the technique in order to reduce the number of samples that need to be analyzed chemically. Therefore the achievable accuracy of the technique is being studied in detail. The accuracy of a neutron multiplicity measurement can be affected by a number of variables. Monte Carlo neutron transport simulations with MCNP have been done to understand how the density, isotopic composition, chemical composition and moisture in the material affect the count rate. These calculated count rates have been analyzed with the ``point model'' in order to determine the effect on the deduced plutonium mass. In practice, dead time in the electronics affects the count rate. Uncorrelated neutron sources have been measured in order to determine optimum settings for dead time compensation. [Preview Abstract] |
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GB.00120: Alternative RPC Coatings Jason Strack The nuclear physics group at the University of Illinois is currently developing techniques to further improve the performance of Bakelite Resistive Plate Chambers (RPCs) for use as muon trigger detectors in experiments at hadron colliders. Muon trigger RPCs at LHC and RHIC typically use Bakelite plates coated with linseed oil. Both Bakelite and linseed oil, however, have high bulk and surface resistivity thus limiting the detection efficiency of the RPC at high rates. Experiments which dope the linseed oil with either carbon or copper are carried out with the goal to select targeted lower surface resistivity values for the coating applied to the Bakelite plates. Two doping procedures have been studied. In the first method a thin layer of graphite is deposited between the Bakelite and the linseed oil.~ For the second method the graphite or copper powder are deposited on top of the drying linseed oil coating.~ In this presentation the coating methods will be discussed and the effects of the coating on the RPC position resolution, cluster size and efficiencies will be discussed. [Preview Abstract] |
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GB.00121: Production and Separation of Radioactive Beams $^{20}$Na and $^{20}$Mg with MARS Gopal Subedi, B.T. Roeder, A.A. Alharbi, M. McCleskey, E. Simmons, A. Spiridon, L. Trache, R.E. Tribble We studied the production and separation of $^{20}$Na and $^{20}$Mg using the MARS spectrometer at the Cyclotron Institute, TAMU. Using a $^{20}$Ne beam at 25 MeV/u on a H$_{2}$ gas target at 2 atm and 77 K, a large production of $^{20}$Na was observed. Further, we were able to study its $\beta $, $\beta \gamma $, and $\beta $-delayed $\alpha $-decay. For the $\beta $-delayed $\alpha $-decay, we observed alphas with energies 2.1, 3.8, 4.4, 4.8 MeV. Following this run, we ran a test experiment to obtain the maximum production of the rarer isotope $^{20}$Mg with the same $^{20}$Ne beam on a $^{3}$He gas target. The gas cell was filled with $^{3}$He at 1.5 atm and 77 K. Overall, the fusion-evaporation of $^{20}$Ne($^{3}$He,3n) was found to be a better reaction for $^{20}$Mg production than the fragmentation of $^{24}$Mg at 45 MeV/u previously tested with MARS. These findings will be used for planning an upcoming study of the $\beta $-delayed proton decay of $^{20}$Mg to better understand the resonance states in the $^{19}$Ne(p,$\gamma )^{20}$Na reaction of crucial astrophysical interest in studies of the hot CNO cycle in stars. [Preview Abstract] |
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GB.00122: Development of the Low-cost Analog-to-Digital Converter (for nuclear physics experiments) with PC sound card Kenkoh Sugihara A low-cost ADC (Analogue-to-Digital Converter) with shaping embedded for undergraduate physics laboratory is developed using a home made circuit and a PC sound card. Even though an ADC is needed as an essential part of an experimental set up, commercially available ones are very expensive and are scarce for undergraduate laboratory experiments. The system that is developed from the present work is designed for a $gamma$-ray spectroscopy laboratory with NaI(Tl) counters, but not limited. For this purpose, the system performance is set to sampling rate of 1-kHz with 10-bit resolution using a typical PC sound card with 41-kHz or higher sampling rate and 16-bit resolution ADC with an addition of a shaping circuit. Details of the system and the status of development will be presented. Ping circuit and PC soundcard as typical PC sound card has 41.1kHz or heiger sampling rate and 16bit resolution ADCs. In the conference details of the system and the status of development will be presented. [Preview Abstract] |
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GB.00123: Trace-Element Analysis by Use of PIXE Technique on Agricultural Products A. Takagi, R. Yokoyama, K. Makisaka, K. Kisamori, Y. Kuwada, D. Nishimura, R. Matsumiya, Y. Fujita, M. Mihara, K. Matsuta, M. Fukuda In order to examine whether a trace-element analysis by PIXE (Particle Induced X-ray Emission) gives a clue to identify production area of agricultural products, we carried out a study on soy beans as an example. In the present study, a proton beam at the energy of 2.3MeV was provided by Van de Graaff accelerator at Osaka University. We used a Ge detector with Be window to measure X-ray spectra. We prepared sample soy beans from China, Thailand, Taiwan, and 7 different areas in Japan. As a result of PIXE analysis, 5 elements, potassium, iron, zinc, arsenic and rubidium, have been identified. There are clear differences in relative amount of trace-elements between samples from different international regions. Chinese beans contain much more Rb than the others, while there are significant differences in Fe and Zn between beans of Thailand and Taiwan. There are relatively smaller differences among Japanese beans. This result shows that trace-elements bring us some practical information of the region where the product grown. [Preview Abstract] |
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GB.00124: Design of a high-precision $\beta$-telescope R.H. TerBeek, S. Behling, D. Melconian The question is raised of whether or not parity is maximally violated in the weak interaction, focusing on $\beta$ decay. Efforts to measure the neutrino asymmetry parameter, $B_\nu$, and how it will provide limits on the existence of a new right-handed $W$ boson are described. In this experiment, a magneto-optical trap is used to laser-cool and confine $^{37}$K atoms, which are then polarized using optical pumping techniques. A $\beta$-telescope will be used to detect the energy and direction of the $e^+$s emitted from the decay. This detector will be used in coincidence with a microchannel plate which observes the momentum of the recoiling $^{37}$Ar nucleus. The kinematics of the decay allow us to deduce the neutrino's momentum event-by-event, and so by correlating the neutrino's momentum with the initial nuclear spin, we will be able to make a precision measurement of $B_\nu$. The physics of positron detection and constraints on $\beta$-telescope design are covered in detail, as well as research into computer simulation methods for the analysis of response functions and the optimization of certain parameters of a $\beta$-telescope. [Preview Abstract] |
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GB.00125: Possible sub-barrier hindrance in the fusion of light nuclei Spencer Angus Thomas, Xiaodong Tang, Masahiro Notani, Brian Bucher, Chi Ma, Xiao Fang, Larry Lamm, Cheng-Lie Jiang Fusion reactions between light nuclei have been studied because of the significance of their reactions for a wide variety of stellar burning processes. Since the experimental data are limited to energies higher than those of astrophysical interest, S-factors must be extrapolated using theoretical model calculations. Recently, an unexpected hindrance of heavy-ion fusion cross sections has been observed at sub-barrier energies, which could affect the astrophysically important fusion reactions. To investigate the hindrance effect, we have measured the cross sections for the $^{12}$C($^{13}$C, p)$^{24}$Na reaction through measurement of $\beta $-decay of $^{24}$Na by the $\beta \gamma $-coincidence method. We developed a cosmic-ray veto system required for the low background coincidence measurements. The background suppression achieved with the veto system allowed us to measure the fusion cross sections at extreme sub-barrier energies, below the lowest energies previously studied. [Preview Abstract] |
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GB.00126: Creation of a Program to Calculate Thermonuclear Reaction Rates for Stellar Explosion Research Kyle Thomsen, Michael Smith, Ray Kozub, Eric Lingerfelt Current models suggest that sequences of hundreds to thousands of thermonuclear reactions form heavier elements in the various stages of stellar life cycles, including their explosive deaths. To provide input for these studies, a program has been written that accommodates many combinations of experimental and theoretical nuclear data to calculate the nonresonant, narrow resonant, and broad resonant contributions to the rates of these reactions. This program will help researchers quickly and easily calculate thermonuclear reaction rates. It will be incorporated into the Computational Infrastructure for Nuclear Astrophysics (CINA) [1], an online system that is used by researchers in 70 institutions in 20 countries for astrophysics research. We have used this new program to calculate a new rate of proton capture on $^{17}$F, which influences the amount of $^{18}$F synthesized in novae. This new rate is based on the first direct measurement of the strength of the dominant resonance [2]. [1] M.S. Smith et al., Proc. Nuclei in the Cosmos IX, 2006. [2] K.A. Chipps et al., Phys. Rev. Lett. 102 (2009) 152502. [Preview Abstract] |
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GB.00127: Simulation of NIFFTE TPC Remington Thornton The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration's Time Projection Chamber (TPC) is designed to make high precision fission cross-section measurements. These measurements have long-term applications for future generations of nuclear power plant designs. An important component of this project is accurate simulation of the active volume including the physical features of the tracks and the electronics. Tracks are generated using the Geometry And Tracking (Geant4) simulation code, while the detector response simulation is custom written. After reading in tracks, from the Geant4 simulations, the detector response simulation transforms the data using a series of modules with behavior characterized by the TPC design. Asynchronous trigger, 3-D charge diffusion, capacitive charge sharing, digitization, random trigger cells, and noise from the electronics have been modeled. The detector response simulation was designed and written so that it can be reused in future TPC projects. This poster will focus on how these detector response modules are produced and used. [Preview Abstract] |
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GB.00128: Spectroscopic Factor and ANC Sensitivity to Single Particle Parameters and Global Optical Potentials Luke Titus For over 40 years direct transfer reactions, such as (d,p), (d,n) and ($^{3}$He,$\alpha )$, have been the key tool to extract structure information, usually in the form of a spectroscopic factor (SF), as well as information of interest for astrophysics. Transfer reactions are gaining popularity for the study of exotic nuclei. A systematic study was performed to investigate the sources of uncertainties in spectroscopic factors resulting from the choice of global optical potentials (GOPs). A 15{\%} uncertainty in the cross section at the first peak of the theoretical distribution was observed. Also, the sensitivity of the asymptotic normalization coefficient (ANC) on single particle parameters was analyzed. The ANC was found to be insensitive to single particle parameters for peripheral reactions. However, uncertainties resulting from GOPs prevent an accurate theoretical determination of the highest energy at which a reaction becomes peripheral. [Preview Abstract] |
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GB.00129: Precision Measurement of the Neutron d2: Towards the Electric ?E and Magnetic ?B Color Polarizabilities Wolfgang Troth Jefferson Lab Experiment 06-014 was performed to measure the spin-dependent structure function, g2, by measuring the parallel and perpendicular asymmetries of longitudinally polarized electrons scattering off of both longitudinally and transversely polarized 3He. Energies were solely in the deep inelastic valence quark region. By determining the higher twist piece of the structure function, we will be able to evaluate the quantity d2n. The experiment details and the 3He target will be discussed. [Preview Abstract] |
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GB.00130: Production of high $p_{T}$ $J/\psi$ in p+p collisions at $\sqrt{s_{NN}}=200$ GeV in STAR Barbara Trzeciak Suppression of the $J/\psi$ production by color screening in ultra-relativistic heavy-ion collisions was suggested as the signature of the Quark-Gluon Plasma formation. Measurement of $J/\psi$ production in p+p collisions is a baseline measurement which allows to verify the $J/\psi$ suppression in A+A collisions and could provide information about the $J/\psi$ production mechanism. Run 2008 p+p STAR data was taken with reduced detector material, therefore it has significantly reduced background compare to the earlier runs. In this presentation, the preliminary analysis of mid-rapidity $J/\psi$ production at high transverse momentum through dielectron decay channel in p+p collisions at $\sqrt{s_{NN}}=200$ GeV from year 2008 will be shown. [Preview Abstract] |
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GB.00131: Detecting Protons in the aCORN Neutron Beta Decay Experiment Anna E. Walker, Edward J. Stephenson The aCORN experiment will measure the angular correlation coefficient ``little a'' between the electron and the anti- neutrino in neutron beta decay. The goal is to reduce the error on $a=-0.104\pm 0.004$ (PDG value) to less than 0.001 to check the completeness of the $V-A$ model of the weak interaction and the value of $V_{ud}$ in the CKM matrix. The aCORN apparatus selects electrons and protons that, after a +2~kV acceleration, have oppositely directed momenta by restricting the acceptance using a series of tungsten collimators and a co-axial 350-G magnetic field. The lack of transverse anti-neutrino momentum for the selected decays creates two event groups with the anti- neutrino momentum either parallel or anti-parallel to the electron momentum and whose rate asymmetry measures $a$. These groups are distinguished using proton time of flight to a silicon detector. Proton detector electronics was tested for installation in a confined tube where it will be cooled with liquid nitrogen and mounted on a $-30$-kV acceleration platform to separate the proton signal from noise. An optical link transfers the signal to the data acquisition system. Spectra of 60-keV gamma rays from $^{241}$Am were used as a test signal. [Preview Abstract] |
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GB.00132: Modeling radon daughter deposition rates for low background detectors S. Westerdale, V.E. Guiseppe, K. Rielage, S.R. Elliot, A. Hime Detectors such as those looking for dark matter and those working to detect neutrinoless double-beta decay require record low levels of background radiation. One major source of background radiation is from radon daughters that decay from airborne radon. In particular, $^{222}$Rn decay products may be deposited on any detector materials that are exposed to environmental radon. Long-lasting daughters, especially $^{210}$Pb, can pose a long-term background radiation source that can interfere with the detectors' measurements by emitting alpha particles into sensitive parts of the detectors. A better understanding of this radon daughter deposition will allow for preventative actions to be taken to minimize the amount of noise from this source. A test stand has therefore been set up to study the impact of various environmental factors on the rate of radon daughter deposition so that a model can be constructed. Results from the test stand and a model of radon daughter deposition will be presented. [Preview Abstract] |
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GB.00133: Implanted Helium Targets for Use in Inverse Kinematics Reactions J.L. Wheeler, R.L. Kozub, D.J. Sissom, D.W. Stracener, D.W. Bardayan, C. Jost Proton transfer reactions, such as ($^{3}$He,d), are extremely important for gathering information about single particle states and resonances. For example, near-threshold resonances, which may be important in the rp process of explosive nucleosynthesis, cannot be measured via resonance scattering directly. However, measurements involving proton transfer reactions with radioactive ion beams (RIBs) in inverse kinematics also involve a number of experimental challenges. For the ($^{3}$He,d) reaction, for example, it is necessary to use localized $^{3}$He targets, and gas jet targets are expensive and difficult to construct. This problem can be alleviated by implanting $^3$He into aluminum foils. We have begun the process of implanting $^{3}$He and $^{4}$He into aluminum foils of two different thicknesses (0.65 and 0.8 ${\mu}$m) at the On-Line Test Facility at ORNL. Target profiles will be analyzed using Rutherford backscattering to determine the concentration and distribution of the implanted He on the foils. These results and a detailed description of the technique will be presented. This research is supported by the U.S. Department of Energy. [Preview Abstract] |
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GB.00134: Electronics and Data Acquisition for miniLENS M.M. White, J.C. Blackmon, L.E. Linhardt, C. Pangan 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 acqusisiton system for miniLENS will be presented. [Preview Abstract] |
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GB.00135: Designing Electronics and PMT Housing for a Liquid Scintillator Detector to be Used for Measuring Muon-Induced Processes at Homestake Brian Woltman, Patrick Davis, Dongming Mei, Chao Zhang Understanding the backgrounds produced by muon-induced processes is important to the success of experiments searching for rare event physics such as neutrinoless double-beta decay, dark matter, or neutrino oscillations, which require extremely low backgrounds. Measuring these muon-induced processes is vital for the low background experiments planned for the Sanford Lab. We have designed a detector to measure the muon-induced backgrounds produced underground. Our detector consists of a 10.8 liter scintillator joined with two PMT's. We will present our design for housing the PMT's, including their attachment to the scintillator and necessary magnetic shielding. We will also present our design for a voltage divider that was constructed and tested for use on each of the PMT's. [Preview Abstract] |
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GB.00136: Quality Control of the PHENIX Resistive Plate Chambers being produced for the Forward Trigger Upgrade Ryan Wright The PHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Lab uses polarized proton-proton collisions to study the spin structure of the proton by reconstructing muon tracks produced from these collisions. As RHIC moves to higher energies, a new $W$-boson physics program is accessible, requiring the existing muon trigger system to be upgraded allowing for triggering on high $p_T$ muons produced from $W$ decays. One of the upgrades is the addition of fast Resistive Plate Chambers (RPC) made from Bakelite to give position and timing information for muons produced from W-boson decays. Before these chambers are installed in PHENIX, they must be tested for quality assurance to ensure proper performance with minimal failures in the future. These tests are conducted in a dedicated cosmic ray test stand in the RPC factory. Tests preformed on each RPC include measuring the dark current, cluster sizes, and gap efficiencies. These test identify bad gas gaps and modules while in the construction phase where repairs and modifications can be made. I will present the module quality assurance process and data recorded from these tests. [Preview Abstract] |
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GB.00137: String theory: a model beyond popular physics Edward Wunder String theory was originally proposed as a theory of hadrons in the 1950's. Though its nuclear roots were eventually supplanted by quantum chromodynamics, string theory continues to hold significant potential. The physical and mathematical ideas of such a theory are easily extended to all branches of theoretical physics. For the layperson interested in string theory, there is a vast amount of accessible literature. However, when one chooses to seek a level of understanding beyond popular physics, the prerequisite knowledge renders the subject inaccessible. It is my intention to provide a more involved understanding of the basic ideas of bosonic string theory at a level that requires only the solution of the differential equations found in every undergraduate physics class. Beginning with the classical action for a point particle, we will follow a series of logical steps to illustrate how strings can manifest as a variety of bosons. While this model of string theory lacks fermions, its purpose as a pedagogical tool cannot be underestimated. [Preview Abstract] |
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GB.00138: Search for the alpha-cluster 2$^{+}_{2}$ state in $^{12}$C Naoki Yokota Alpha particle clustering is an important concept in nuclear physics. Many works were devoted to examine the alpha-cluster structure in atomic nuclei. The $^{12}$C nucleus is one of the well-investigated nuclei, and its energy level is successfully explained by the alpha-cluster-model (ACM) calculations except for the 2$^{+}_{2}$ state. The ACM calculation strongly suggests the 2$^{+}$ state should be observed at E$_{x}\sim $ 10 MeV. Recently, Itoh et al suggested both the 0$^{+}$ and 2$^{+}$ states exist in a broad bump at E$_{x }\sim $ 10 MeV in $^{12}$C, but Fynbo et al claimed they observed no 2$^{+}$ states in the bump. Thus the existence of the 2$^{+}_{2}$ state is still controversial. We propose to measure the cross sections for the $^{16}$O(d,$^{6}$Li) reaction at E$_{d}$ = 45 MeV to search for the 2$^{+}_{2}$ state in $^{12}$C. We will perform the multipole-decomposition analysis on the basis of the DWBA calculation and pin down the 2$^{+}$ strengths in the broad bump at E$_{x }\sim $ 10 MeV. We will use a $\Delta $E-E Si counter to detect reaction products. This counter consists of two Si strip detectors with the thicknesses of 65 $\mu $m and 500 $\mu $m. We performed a test experiment and confirmed the performance of the $\Delta $E-E Si counter is good enough to carry out the proposed measurement. [Preview Abstract] |
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GB.00139: Asymptotic Normalization Coefficients from 3He + 4He and Astrophysical Factor for 3He + 4He -$>$ 7Be + gamma Susan Zhang The 3He + 4He $\rightarrow$ 7Be + gamma reaction is an especially important pp-chain reaction for the determination of high-energy neutrino-flux from 8B decay. The goal of this project is to draw the attention of experimentalists toward the possibility of determining the astrophysical factor for this reaction using elastic scattering 3He + 4He phase-shift data at l = 1. Since this reaction is peripheral at astrophysically relevant energies, the only unknown quantity for calculating the S factor is the asymptotic normalization coefficient (ANC) of 3He + 4He $\rightarrow$ 7Be. This ANC can be determined by extrapolating the scattering amplitude to the poles in the momentum plane corresponding to the ground and excited states of 7Be. For extrapolation, the effective-range theory has been used in the form of the Pad\'{e}'s approximation. Unfortunately, the available measurements are outdated and have large uncertainties, which lead to a corresponding spread in the extracted ANC values. For the astrophysical factor I obtain, 0.36 $<$ S(0) $<$ 0.51 keV b. Improvement of experimental phase-shift data will allow one to obtain a more accurate value of the ANC and S(0). The same technique can be applied for other important astrophysical reactions. [Preview Abstract] |
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