Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session JA: Conference Experience for Undergraduates Poster Session III (5:20pm - 5:55pm) |
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JA.00001: Further Optimization of an Ultracold Neutron Spin Dynamics Simulation Code Christian Swindell The UCN$\tau$ experiment is designed to measure an ultracold neutron’s (UCN’s) mean lifetime when trapped by a magnetic field before undergoing beta-decay. One value needed to determine this lifetime to high precision is a UCN’s depolarization rate. This value is difficult to measure empirically because it’s very small, but simulations may be used to estimate it. One simulation we are developing can be validated by comparing to actual trap lifetimes measured at different holding fields. Due to the amount of required computation, on a 10-core computer running Ubuntu 16.04 this code initially took about 36 hours to simulate 100 disjoint UCNs; but we really want to simulate in batches of millions of UCNs to get good statistics, which would take over 40 years to complete on the same hardware when scaled up. Optimization of the simulation code was required for better time efficiency. This code was fully converted to C++ from Python after trying optimization methods in Python and before using basic parallel programming methods, resulting in code 169 times faster than its Python equivalent. Interesting issues encountered during the conversion process, optimization methods used, and parallel programming methods used with and without a GPU to further enhance efficiency will be presented. [Preview Abstract] |
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JA.00002: ABSTRACT WITHDRAWN Joshua Adams |
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JA.00003: Visualization and Interpolation of Field Mapping Data Anita Agasaveeran, Thomas Baumann, Paul Gueye The MoNA Collaboration utilizes a large-gap (14 cm) high-field (4 T) Sweeper dipole magnet in invariant mass studies of neutron-unbound states. For the invariant mass reconstruction, charged particles need to be tracked through the magnetic field of the Sweeper. 2D planar maps of the vertical component of the magnetic field were measured across the gap when the magnet was commissioned using an array of seven Hall probes placed at different vertical positions. The collected data is being analyzed to generate a 3D field map. Techniques to visualize and and interpolate the measured field map will be presented and discussed. [Preview Abstract] |
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JA.00004: Simulations of various GEM foil hole geometries using Garfield$++$ Pham Phuonganh The Gaseous Electron Multiplier (GEM) detector is used to detect ionizing radiation. A GEM detector consists of a gas filled volume containing a thin polymer layer that is coated with metal on both sides. The thin layer is perforated to achieve a high density (50 - 100 mm-2) of small holes with diameters of roughly 50 microns. A large potential difference (typically 400 V) is applied between the two metal surfaces in order to create a large electric field inside the holes, thus producing an electronic avalanche from the electrons created by the ionization of gas molecules by the incoming radiation. The electron shower drifts to a collection electrode where they produce a measurable charge that is proportional to the energy deposited by the radiation in the gas volume. Simulations using Garfield$++$ were run for five different geometries with various sizes (top/middle/bottom \textmu m): double conical (70/50/70 \textmu m), conical (30/50/70 \textmu m), inverted conical (70/50/30 \textmu m), cylindrical (70/70/70 \textmu m), and cylindrical-50 (50/50/50 \textmu m). Preliminary simulations show that a larger hole size will allow more electrons to pass through the GEM layer, however, a reduction in gain due to a smaller hole size can be compensated by a higher density of electric field lines which produces a larger avalanche. [Preview Abstract] |
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JA.00005: Using neural networks to generate cross section data from theoretical QCD parameters Rida Shahid, Eleni Tsitinidi, Yasir Alanazi, Manal Almaeen, Michelle Kuchera, Yaohang Li, Wally Melnitchouk, Raghu Ramanujan, Nobuo Sato Theoretical codes are used to map from the theoretical Quantum Chromodynamics parameter space into observable cross-section space. For QCD applications, each sample in the multidimensional parameter space is processed with respect to observables across all kinematics. This is a time-consuming way of generating cross section data, and we propose using a neural network architecture to quickly and accurately mimic the experimental high-energy scattering data. A neural network is trained on a subset of the QCD parameter space that characterize nucleon structure. The trained model can then quickly generate large amounts of cross section data satisfying the multidimensional parameter distribution. The augmented data can be used in a variety of applications, one of which is to serve as training samples for the inverse problem of mapping to multiple solutions in parameter space. The results can also be useful in establishing a new paradigm for the analysis of various high-energy reactions. [Preview Abstract] |
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JA.00006: Behavior of Neutrons in Plastic Scintillators$\backslash $ Caroline Capuano, Andrea Robinson, Anthony Kuchera, Paul Gueye h $-abstract-$\backslash $pardThe purpose of this experiment is to measure the scattering behavior of neutrons in plastic scintillators, to improve the simulations of nuclear interactions. The experiment was conducted at the LANSCE WNR facility at Los Alamos National Laboratory using a neutron beam of energies ranging from 20 to 400 MeV and trajectory targeted on 16 BC-408 plastic scintillator detectors from the Modular Neutron Array arranged in an ascending horizontal array. The configuration of the scintillators will improve the data set used for simulations of neutron interactions. The multiple neutron production and the scattering angle probability, velocity, and energy between the first and second hit of the neutrons were examined with the data collected from the experiment. The results showed that the new configuration improved the data set collected and, in the future, will help improve the accuracy for higher energy simulation. It is important to improve and analyze the behavior of the scattered neutron because the simulation packages for higher beam and neutron energies are less accurate above 200 MeV. $\backslash $pard$\backslash $pard-/abstract-$\backslash $\tex [Preview Abstract] |
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JA.00007: The Fermilab E1039 Spectrometer Emily Branson SpinQuest (E1039) at Fermi National Accelerator Laboratory seeks to measure the Sivers Function, which is related to orbital angular momentum of the quark sea. E1039 will collide a 120 GeV unpolarized proton beam from the FNAL main injector with solid ammonia NH3 and ND3 targets polarized transversely to the beam. Spin asymmetries of dimuons produced in Drell-Yan events will be measured in order to extract the Sivers Function. These dimuons are tracked through the SpinQuest spectrometer, which is using the upgraded SeaQuest spectrometer, passing first through a solid iron focusing magnet -- which also serves as a beam dump -- to the station one hodoscope array and drift chamber. Next is the open-air momentum-measuring magnet followed by hodoscope arrays and drift chambers at stations two and three. Finally, there is an iron wall for absorbing hadrons before the station four hodoscope array and proportional tubes. An overview of the SpinQuest experiment, including the modifications and additions to the SeaQuest spectrometer, will be presented. [Preview Abstract] |
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JA.00008: Coupling the Lattice QCD Equation of State to the Liquid-Gas Phase Transition Bore Gao, Débora Mroczek, Jacquelyn Noronha-Hostler Here we use a van der Waals equation of state to simulate the liquid-gas phase transition in order to map it into the high-temperature equation of state reconstructed from Lattice Quantum Chromodynamic (QCD) that also has a high-temperature critical point from a parameterized 3D Ising model. Previously, only an ideal hadron resonance gas was used for this equation of state. Instead, we use the van der Waals equation of state with the grand canonical ensemble (GCE) formulation with quantum statistics, which incorporates constants that represent attractive and repulsive interactions. We used the comprehensive list of particles (the PDG16+) and adjusted the interaction terms in order to reproduce the location of the liquid-gas phase transition. [Preview Abstract] |
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JA.00009: Performance Characterization Studies of sPHENIX Hadronic Calorimeter Scintillating Tiles Jacob Tutterow At Georgia State University, we are studying the performance characterization of sPHENIX Hadronic Calorimeter (HCal) scintillating tiles. These tiles are shipped to Brookhaven National Lab to be installed in a next-generation jet detector at the Relativistic Heavy Ion Collider (RHIC). The tiles are placed in steel absorber plates in groups of five, called towers. To improve the energy resolution, sPHENIX requires HCal towers to be composed of scintillating tiles of similar light yield. These tiles scintillate when struck by an incoming particle, which is then collected by a wavelength shifting fiber that sends the light to a silicon photomultiplier (SiPM). Our quality assurance requires testing each tile using cosmic rays to determine performance characteristics. A performance ratio is determined for each tile based on the most probable value extracted from the ADC distribution. To compare tiles across tests, two reference tiles are used in every test and are used to normalize the performance ratio. This poster will present the status of the HCal tile testing and assembly. [Preview Abstract] |
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JA.00010: Simulations of neutron spin ``gymnastics'' for nEDM P/T measurement Lara Blokland, Scarlett Wilson, Nadia Fomin, Geoffrey Greene, Kavish Imam The nEDM@SNS experiment uses a cryogenic apparatus to search for the neutron electric dipole moment. Ultra-cold neutrons are produced using superfluid $^{\mathrm{4}}$He, and $^{\mathrm{3}}$He is used as a co-magnetometer and spin analyzer. The Larmor precession frequency of the neutrons will change if there is an electric dipole moment in the presence of an electric field. It's important to understand the magnetic fields in the apparatus, as well as the polarization loss and transmission efficiency of the neutrons. I'll present results of simulating the magnetic fields in Python using Bloch equations to characterize the spin precession through the apparatus. [Preview Abstract] |
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JA.00011: Simulating Neutron Rotations in Magnetic Fields Justin Chovanec Neutron polarization can be used to study the weak interaction and to look for fifth forces. This is done by analyzing deviations in the polarization of a neutron beam as it passes through a non-polarized substance. For example, to study the weak interaction, a beam of neutrons is sent through liquid helium, which can cause a rotation of the neutron polarization through the weak interaction. These changes can be detected with a neutron polarimeter that has been developed by the Neutron Spin Rotation collaboration. To search for fifth forces, a different target is used, but the experiment is very similar. In both cases, ambient magnetic fields can also affect the polarization of the neutron beam and lead to systematic errors. This project focused on improving pre-existing neutron spin transport code and writing new code to improve the computer model for the experiment, with a heavy emphasis on writing code to select statistically relevant sets of data from various histograms. Once the improvements to the code are made, simulations will be run on a high-speed computer cluster to study small systematic effects due to magnetic field simulations. This work supports measurements to be conducted on the cold neutron beam at the NIST Center for Neutron Research in the coming year. As experiments are run, the neutron polarimeter will be utilized to measure deviations in the polarity of the neutrons, which will aid in the understanding of the weak interaction and the search for fifth forces. [Preview Abstract] |
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JA.00012: Measurement of Nuclear Isomer Gamma Emissions in Geant4 Lauren Fisher, Andrea Bracamonte, Adam Fritsch, Jim Brown Nuclear isomers have a wide variety of applications, yet many properties, such as energy levels, are not well known. Energy levels are experimentally determined by detecting gamma emission from nuclear de-excitation. Through Monte Carlo simulations, this process has been simulated using various beam and target combinations in Geant4. A detector ring consisting of multiple scintillation detectors has been placed in optimal positions to specifically measure energy from gamma emissions. Using the analysis capabilities of CERN's Root, various physical phenomena have been observed. Since energy levels of neutron-rich isomers are not well identified, excitation states are of particular interest to better develop nuclear structure models. [Preview Abstract] |
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JA.00013: Polarized positron yield optimization based on a two target system for Jefferson Lab Nicholaus Trotta, Joe Grames, Fatiha Benmokhtar The polarized electron beam at the DoE's Continuous Electron Beam Accelerator Facility at Jefferson Lab is used as a probe to study nuclear states of matter. New experiments are being proposed to instead use polarized positrons, the anti-electrons, for complementary measurements. Positrons are produced in the electron-magnetic shower when electron beam strikes a target composed of high-Z atoms. The positron yield relies on depositing 10's of kW of beam power on the target which itself must be nestled close to a high field solenoid magnet used to focus and form the positron beam. Therefore, the efficiency of a conventional ``single-stage'' positron source depends on the design of a sophisticated vacuum volume, which includes: the target, magnetic field, radiation shielding, and challenging thermal loads. As an alternative, we studied a ``double stage'' design with separated bremsstrahlung radiator and pair-production target. In this design, the radiator serves to dissipate the brunt of the electron beam power and might be well-shielded, but illuminates out-coming bremsstrahlung radiation on a second pair-production target. In this contribution, we evaluate the total positron yield and polarization in terms of the thermal and radiative loads, in order to list the pros and cons of both configurations. [Preview Abstract] |
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JA.00014: ~Background Evaluation of the Chiral Vortical Effect Using a Multiphase Transport Model~ Zoë Webb-Mack A possible chirality imbalance within the quark-gluon plasma (QGP) created in high-energy heavy-ion collisions could produce the chiral vortical effect (CVE) [1]. This effect predicts baryon number separation along the vorticity or angular momentum of a chiral QGP fluid with finite baryon chemical potential. Evidence of the CVE-induced separation has been observed in the azimuthal angular correlations between two baryons, Lambda and proton, in experimental data [2]. However, non-CVE background effects must be modeled in order to determine to what extent this separation may be attributed to the CVE. We shall apply the analysis method to heavy-ion events generated by a multiphase transport model (AMPT) [3], estimate pure background contributions to the azimuthal correlations, and help determine the fraction of the CVE in the observed baryonic charge separation. 1. D. E. Kharzeev and D. T. Son, Phys. Rev. Lett.106 (2011) 062301.~ 2. F. Zhao [STAR Collaboration], Nucl. Phys. A931 (2014) 746.~ 3. Z.W. Lin et al., Phys. Rev. C72 (2005) 064901. [Preview Abstract] |
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JA.00015: Examining the Hardness Parameter using the Glauber Model and Multiplicity Distributions from the STAR Beam Energy Scan and Fixed-Target Programs Aaron Poletti The Glauber Model in conjunction with a negative binomial distribution (NBD) has been used to simulate particle production in heavy-ion collisions. Particle multiplicities are generated by drawing random numbers from a NBD some number of times, N, where $N=xN_{Coll} +(1-x)N_{Part}/2$, and $x$ is the hardness parameter. Hardness represents the ratio of hard versus soft processes in the collision. Particle production scales with the number of nucleon-nucleon collisions ($N_{Coll}$) in hard processes and number of participant nucleons ($N_{Part}$) in soft processes. The best fit to the multiplicity data from STAR can be obtained by scanning the three dimensional parameter space consisting of 2 NBD parameters plus the hardness parameter. The dependence of the hardness parameter on $\sqrt{s_{NN}}$ can be studied and used to understand nucleon stopping among other observables. Results from the STAR Fixed-Target and RHIC Beam Energy Scan programs will be presented. [Preview Abstract] |
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JA.00016: RF timing for MUSE and the Proton Radius Puzzle Rujuta Mokal Knowledge about the proton and its radius are fundamental to research in nuclear, particle, and atomic physics. Recently, however, there is an approximately 4{\%} discrepancy in the proton radius measured with muonic hydrogen spectroscopy compared to normal hydrogen spectroscopy or electron proton scattering. This discrepancy is known as the proton radius puzzle. For further investigation of the puzzle, a Muon-proton Scattering Experiment (MUSE) based at the Paul Scherrer Institute (PSI), Switzerland, is being performed. It uses a beam of particles including electrons, muons and pions. The interactions of these particles with the target proton is acquired through detectors and associated electronics. Analyzing the data will check whether the interactions of muons and electrons with protons are the same, will take us closer to an accurate value of the proton radius, and might possibly uncover new physics. I will be discussing recent analyses and observations of the RF time difference between electrons, muons and pions at different momenta and the comparison of these observations with our theoretical predictions. [Preview Abstract] |
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