Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session HA: Conference Experience for Undergraduates Poster Session (2:00pm - 3:45pm) |
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Room: Hilton Grand Promenade |
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HA.00001: Efficiency measurement of next generation scintillator GAGG at high energy using the 992keV resonance of the 27Al(p,γ)28Si reaction Tomohito Amano, Natsumi Ogawa, Wren Yamada, Hiroyoshi Sakurai, Kathrin Wimmer, Megumi Niikura, Takuma Koiwai, Tokihiro Ikeda Efficiency and peak-to-total ratio of gamma-ray detectors are important for γ-ray detection in reactions with small cross sections. Currently at RIKEN a NaI crystal detector array, DALI2, is used for in-beam gamma experiments. However, due to the small effective Z of the crystal, DALI2 has a low efficiency. Thus, new scintillator crystals with high effective Z are required for efficient findings of gamma-lines. A prospective candidate, cerium doped Gd3Al2Ga3O12, or GAGG(Ce), with a large effective Z was recently developed. The immediate objective of this research is to measure the efficiency of the GAGG crystal especially for high energy gamma rays through a coincidence measurement. To produce these high energy gamma rays, the 12.7MeV resonance of the 27Al(p,γ)28Si reaction was used. The experiment was performed at the RIKEN Pelletron, which provides proton beams up to 3 MeV. 4 GAGG crystals, including the largest GAGG crystal produced so far with a size of (35*35*100mm−3), and 9 DALI2 crystals were arranged around the 27Al target. Different combinations of photomultipliers and GAGG detector geometries were used. In this presentation we show the current status of the data analysis and first results on the performance of GAGG as a detector for high energy gamma rays. |
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HA.00002: Resolution measurement of next generation scintillator GAGG at high energy using the 992 keV resonance of the 27Al(p,γ)28Si reaction Natsumi Ogawa, Tomohito Amano, Wren Yamada, Tokihiro Ikeda, Takuma Koiwai, Megumi Niikura, Hiroyoshi Sakurai, Kathrin Wimmer For in-beam γ-ray spectroscopy experiments with fast beams, the resolution after Doppler correction depends strongly on the position and energy resolution of γ-ray detectors. Scintillator based detector arrays usually have rather low energy and position resolution. For experiments at RIKEN RIBF a new detector array based on cerium doped Gd3Al2Ga3O12, or GAGG(Ce), crystals is being developed. The prime objective of this research project is to measure the energy resolution of the GAGG especially for high energy γ-rays. To produce these high energy γ-rays, the 27Al(p,γ)28Si reaction was used. The experiment was performed at the RIKEN Pelletron which provides proton beams up to 3 MeV. Four GAGGs, including the biggest crystal with a size of 35mm*35mm*100mm, and 9 NaI crystals of the existing detector array, DALI2, were arranged around the 27Al target. Different combinations of PMTs and GAGG detector geometries were employed for the test experiment. Standard calibration sources, and γ-ray transitions from resonances in 28Si up to 10.5 MeV were used to determine the energy resolution of GAGG detectors coupled with various types of PMTs. In this presentation we show the current status of the data analysis and first results on the performance of GAGG as a detector for high energy γ-rays. |
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HA.00003: Linearity measurement of next generation scintillatorGAGG at high energies using the 992KeV resonance of the 27Al(p,γ)28Sireaction Wren Yamada, Tomohito Amano, Natsumi Ogawa, Hiroyoshi Sakurai, Kathrin Wimmer, Megumi Niikura, Takuma Koiwai, Tokihiro Ikeda Scintillator detectors provide a very large efficiency for the detection of γ-ray in nuclear physics experiments. However due to the non-linear light output of the crystals, the extrapolation of the calibration parameters obtained using standard sources is not reliable at high energies. A new scintillator, cerium-doped Gd3Al2Ga3O12(GAGG) was recently developed. It has a large effective Z, thus expected to have high peak-to-total ratio and efficiency. The primary purpose of this experiment is to evaluate the linearity of the GAGG light output for high energy γ-rays. To produce these high energy γ-rays, the 27Al(p,γ)28Si reaction was used. This reaction produces a number of γ-ray transitions up to 10 MeV. The experiment was performed at RIKEN Pelletron, which provides proton beams up to 3MeV. Four GAGG crystals with different geometries, and 9 DALI2 crystals were arranged around a 27Al target. Different combinations of photomultipliers and GAGG detector geometries were used. Using standard calibration source, and the γ-ray transitions from resonances in 28Si up to 10 MeV, the linearity of GAGG detectors were characterized. The linearity of DALI2 was also characterized for the first time. Here we show the first results on the performance of GAGG as a detector for high-energy γ-rays. |
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HA.00004: Evaluation of Phoswitch-type scintillation detector to distinguish low-energy charged particles Shiyo Enyo, Takahiro Kawabata, Yoshiko Kanada-En'yo, Kenichi Yoshida, Shunsuke Kurosawa, Akihiro Yamaji, Tatsuya Furuno, Kento Inaba, Yuki Fujikawa, Takanobu Doi, Yui Arakawa, Ryota Kongo, Kousuke Sakanashi, Shu Takagi, Yuto Hijikata, Rinko Matsumoto, Takuya Mikami, Keiko Miyazato It is indispensable for describing the equation of state of nuclear matter that we clarify the property of atomic nuclei not only at standard density but also at low density. One of the theoretically predicted states at low nucleon density is a superfluid condensate of alpha particles. Identifying this state can help describing the equation of state, and therefore, much efforts to search for a condensate of alpha particles have been devoted. Since a condensate of alpha particles decays by emitting multiple low-energy alpha particles, we can identify the condensate by detecting these decay particles. However, conventional detectors are not suitable for such measurements because these detectors are not useful to distinguish low-energy alpha particles from other charged particles. We need a new type of detector to solve this difficulty. We develop a Phoswitch-type scintillation detector, in which a thin layer of scintillation material is fabricated on inorganic scintillation crystal with different time constants. This layer effectively works as a very thin transmission detector which low-energy particles can penetrate, and at the same time has sufficient detection efficiency. In the present talk, we will report details about this detector and its performance. |
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HA.00005: Particle identification method by analyzing pulse shape with neural network Yuto Hijikata, Takahiro Kawabata, Yoshiko Kanada-En'yo, Kenichi Yoshida, Tatsuya Furuno, Kento Inaba, Yuki Fujikawa, Takanobu Doi, Yui Arakawa, Shiyo Enyo, Ryota Kongo, Kousuke Sakanashi, Shu Takagi, Rinko Matsumoto, Keiko Miyazato Recent cluster-model calculations predict that α condensed states emerge in self-conjugate N = 4n nuclei. In the α condensed states, all of the α clusters are condensed in the lowest energy orbit, and their matter density is as low as 1/4 to 1/5 of normal nuclear states. Thus, observation of the α condensed states is important for clarifying physical properties of low-density nuclear matter. |
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HA.00006: nγ separation using deep learning method Kazuki Konishi, Syotaro Kawashima, Hidetoshi Akimune We are measuring photo nuclear decomposition reaction using Laser Compton scattering gamma ray source at NewSUBARU. The purpose of this research is to develop a measuring device for separating neutrons and γ rays with higher precision in order to improve the measurement accuracy. Organic scintillators are often used to measure neutrons of several MeV to several hundred MeV. The main background is a signal caused by Compton scattering of γ rays incident on the scintillator. The time constant of the light emission time of the scintillation light by the protons recoiled by the neutron and the scintillation light by the electrons recoiled by the γ rays is different.When using the data of the whole waveform measured by FADC, information volume is large and it is difficult to be affected by noise. We applied deep learning as a method to use FADC data for particle identification. In order to improve the accuracy of separation by deep learning, it is to use higher purity data as learning data. If noise is mixed in the learning data, accurate learning cannot be used and expected results may not be obtained. Therefore, when neutron data was measured, shielding was carefully considered, and high purity data was obtained. |
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HA.00007: Photonuclear reaction of 20Ne to alpha particles Kyoko Nosaka, Hidetoshi Akimune, Makoto Kinoshita, Kazuya Kitamura, Shugo Nagamine, Motoki Murata, Takahiro Kawabata, Yuki Fujikawa, Tatsuya Furuno, Kento Inaba The alpha cluster model is a model in which the 4He nucleus is regarded as the smallest unit constituting the nucleus. Since 4He nuclei are Bose particles, it is theoretically expected that in the condensed matter physics, properties unique to the well-known Bose particle multi-body system also appear in the nucleus of the Fermi particle multi-body system. Currently, such a unique state is considered to be a gas-like alpha cluster state and experimentally verified in the excited state of 12C. In DUBNA, an experiment in which nuclear nuclei such as 20Ne of several GeV was incident on an emulsion detector has been observed in which incident particles decay into a large number of 4He in the very forward angels. We thought that this event was caused by the nuclei in the emulsion that the alpha cluster state of 20Ne was excited by Coulomb excitation. Therefore, we conducted experiments to irradiate 20Ne with real photons. Using the electron storage ring of the New SUBARU accelerator facility, laser Compton scattering gamma ray was irradiated to 20Ne gas, and the decay from the excited 20Ne into alpha particles was measured with a TPC detector. |
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HA.00008: Precise Half-Life Measurement of Neutron-Rich Nucleus 18N Mariko Hisamatsu Stability of nucleus is related to the balance of proton and neutron numbers. I am keen to study more about such quantum many-body system and decided to measure half-life of unstable nuclei. In this work, I have developed the method to precisely determine the half-life of nuclei which beta decays and measured the half-life of the unstable nuclei 18N. To perform highly precise measurement of beta ray for half-life, the following points were improved; (1) by using the radio-active (RI) beam, impurities could be rejected, (2) beta ray was measured during beam on and beam off, whose time in one cycle was optimized by computer simulation to obtain the highest accuracy, and (3) to correct the number of uncounted events during busy time of computer, which are drastically changed by the count rates, a unique method of event-by-event dead time correction was developed by using clock signal. The 18N nucleus was produced by the direct reaction of 9Be(18O, 18N)9B with 18O beam energy of 169 MeV and beam intensity of 3 μA. The secondary 18N beam was separated by RCNP secondary beam line and transported to a gold foil with beam intensity of ~1000 pps and high purity of ~100%. As a result, we could determine half-life of 18N to be 611±1 ms with the highest accuracy in the reported values. |
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HA.00009: Development of the compact aerogel Cherenkov counter with MPPC KAZUKI OKUYAMA We have been investigating hadron production experiments using a tagged photon beam (Eγ<1.3GeV) at the Tohoku University ELPH. We have recorded the data including the e+e- background events to avoid a bias in the acceptance. It is necessary for efficient data taking to remove the e+e- events in the trigger level with high rate beam. The maximum momentum of e+/e- is 1.3GeV/c and we are developing an compact Aerogel Cherenkov counter (ACC) using a refractive index of 1.01 to separate e/π in the momentum range. The size of the aerogel is about 3 x 6 x 4[cm^3]. Since the ACC is placed in the magnetic field, we have plan to use a fine mesh dynode type PMT or MPPC (SiPM) to detect the Cherenkov light. In general, the photon detection efficiency of MPPC is higher than PMT, but it depends on the way of installation. We will report test results about reflector, and photon sensors. Additionally, we will show a bias voltage dependence of gain about MPPC for production version. |
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HA.00010: A three-dimensional measurement of cosmic muon with a spark chamber TAMAO SAKAO "Muon tomography" is an analysis method of object structure with cosmic muon transmission. It has been used to analyze the amount of reinforced concretes of buildings, or the structure of volcanos, pyramids, and blast furnaces in ironworks. Additionally, the method is applied to the reactor core of the Daiichi (first) Fukushima Nuclear Poer Plant. We used a cube spark chamber to measure the zenith angle distribution of cosmic-ray flux. To reconstruct the three-dimensional tracks, photos of the spark chamber were taken from two different directions at the same time. A coincidence signal of the plastic scintillation counters was used as a trigger for a switch of high voltage power supply to the spark chamber and the cameras. We have the plan to observe the cosmic-ray some places: close to windows, upstairs, downstairs, and other locations. From those data, we would like to estimate the amount of substance of the building. |
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HA.00011: Measurement of 103Rh(n,γ) reaction for T-violation search Yuika Tani, Hiroyuki Fujioka, Jun Koga, Shusuke Takada, Sou Makise, Tamaki Yoshioka, Hirohiko M Shimizu, Katsuya Hirota, Masaaki Kitaguchi, Tomoki Yamamoto, Shunsuke Endo, Kohei Ishizaki, Takumi Sato, Yudai Niinomi, Takuhiro Fujiie, Masataka Iinuma, Takuya Okudaira, Atsushi Kimura, Kenji Sakai, Takayuki Oku, Christopher Haddock, Takashi Ino It is known that P-violation in the (n,γ) reaction cross section of the compound nucleus, which is formed by neutron absorption into a nucleus, is enhanced by a factor of 106, compared to that of proton-proton scattering. The enhancement is considered to be due to an interference between s-wave and p-wave resonances. In addition, T-violation may be enhanced for a compound nucleus in which P-violation is enhanced. We plan to search for T-violation with a polarized neutron beam and a polarized target in future. Among a number of target nuclei with large P-violation observed, we chose 103Rh, and measured the 103Rh(n,γ) reaction at the J-PARC/MLF BL04 beamline in June 2018. |
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HA.00012: The evaluation test for the newly developed high-resolution neutron detector HIME (HIgh-resolution detector array for Multi neutron Events) Akira Yasuda I report the evaluation of the electronics and light guides which will be used in the newly developed high-resolution neutron detector HIME (HIgh-resolution detector array for Multi neutron Events). HIME has been developed to study the strong neutron-neutron correlation called dineutron which requires high resolution both in the time and position. The high resolution for the two neutrons emitted in the reaction of very neutron-rich nuclei in required for HIME. HIME is composed of 50 pieces of plastic scintillators, each of which has a size of 2cm(t)×4cm(w)×1m(H), arranged into 5 Layers installed alternately. Such high-granularity of HIME enables us to perform recoil proton tracking which can help us to identify multi-neutron events more efficiency and to improve the angular resolution. Currently, we are making a test of the electronics and light guide of HIME to optimize its performance. I will report the detail of such the evaluation test. |
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HA.00013: Identification of Neutral Particles with PANDORA Detector and Pulse-Shape Discrimination Method YUYA HAMANO Spin-isospin excitations provide a unique opportunity to |
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HA.00014: Study of neutron production processes via (d, n) reactions with time-of-flight method Higashi Masato The (d,n) reactions for C--Co targets have been systematically studied at 55 MeV. At a forward angle of 9.5 degrees, the continuum bumps dominate the cross sections. The peak cross sections have been well described by the A^2/3 dependence on the target mass number A.This A-dependence means that the breakup cross sections are proportional to the geometrical cross sections of the targets. The peak energy is about half of the incident deuteron energy, and decreases with increasing A.The peak width in FWHM also decreases gradually with increasing A.These features can be reasonably reproduced qualitatively by considering the Coulomb force effects. However, significant discrepancy was also observed especially for C and Al targets, suggesting the resonance contributions from 13N and 28Si.Thus we have obtained new data at 0 degrees where the non-resonant proton-stripping process becomes more dominant, and thus the resonance effects would be small. Furthermore, thick-target neutron yields (TTNYs) have been also measured. In a simple reaction model, the TTNYs are expected to be independent of A. However, complicated reaction processes such as the secondary reaction would cause the A-dependence. We will present these new data and compare them with recent theoretical calculations. |
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HA.00015: Development of scintillation counter with ultra high time resolution and its application to research of fragment momentum distributions Miki Fukutome, Mitsunori Fukuda, Daiki Nishimura, Takeshi Suzuki, Maya Takechi, Takashi Ohtsubo The measurement of the time of flight of charged particles by a fast scintillation counter can give the accurate particle velocity that is important information for particle identification. In order to improve the resolution of particle identification, it is effective to improve the velocity resolution, namely, the time resolution of the scintillation counter. Recently, Hamamatsu Photonics Co., Ltd. developed a new type of ultra high speed photomultiplier tube. On the other hand, Eljen technology develops high-speed scintillators. In this study, we developed a scintillation counter with an extremely good time resolution by combining these two. As an application of the detector developed in this research, we consider the following. In this research, we aim to measure the momentum distribution of 15N produced in the one neutron removal reaction of 16N secondary beam using the developed counter. In order to test the performance of this detector, we measured the time resolution using primary beams such as 132 Xe at 420A MeV and others at the HIMAC synchrotron accelerator facility at National Institute of Radiological Sciences. In the presentation we will report on the final results of this test experiment. |
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HA.00016: Automatic control of microscope for double hypernuclei detection in nuclear emulsion sheet Ayumi Kasagi, Kazuma Nakazawa, Junya Yoshida, Masahiro Yoshimoto Double hypernuclei (S=-2 nuclei) are important object to study the system with strangeness -2. We use nuclear emulsion sheet to detect them. The emulsion sheet is able to record the formation and the decay of S=-2 nuclei. When we take image data via microscope, the data becomes as much as 10 terabytes with 1 emulsion sheet. In the past experiments as KEK-PS E373, we succeeded to found the interaction energy between lambdas on a 6He_LL for the first time in the world. However, it took several years for the search of S=-2 nuclei, because human have to watch the microscope image in Personal Computer. On J-PARC E07 at J-PARC, it was designed to obtain ten times more S=-2 nuclei than those of previous experiments within 2 years. Furthermore, we aim at 100 times statistics of the previous experiment with "overall scanning method"(VP), which will be applied for the whole area of the emulsion sheet by image taking with high speed microscope and image processing to find typical topology of S=-2 nuclei. The scanning system of the VP and some results will be introduced in detail. |
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HA.00017: Development of proton detectors using CsI(Tl) scintillator and SiPM Mako Osada, Takashi Teranishi, Yuki Ueno, Shohei Oka, Kotaro Iribe, Hidemitsu Sakai, Taishi Kubo Experimental information on unstable nuclei, which is crucial to improve nuclear theory, can be investigated using radioactive isotope (RI) beams. We are developing recoil proton detectors useful for proton resonant scattering experiment with RI beams. Typically, a recoil detector needs to cover energies up to 20 MeV. A ΔE-E silicon detector with a total thickness of 2.5 mm meets this requirement. However, such a detector is expensive and CsI(Tl) scintillators are often used as cheaper alternatives to thick silicon detectors. We developed prototype detectors combining a CsI(TI) crystal of 5.5 × 5.5 × 5.5 mm3 and SiPM (Silicon Photomultipliers) which became available in recent years. We fabricated three detectors with different SiPM with pixel pitches of 25, 50, and 75 μm, respectively, in order to study energy nonlinearity due to dead-time effect in photon counting of SiPM. Energy resolution, energy linearity, and particle identification resolution were evaluated using proton and deuteron beams from the tandem accelerator at Kyushu University. We will report the results of the detector test and show plans of testing detectors in some reaction measurement and developing detectors with larger crystal sizes. |
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HA.00018: Beta-delayed neutron emission studies in 78Ni region with VANDLE at RIBF Ian Cox, Robert K. Grzywacz, Rin Yokoyama, Thomas T King, Jeremy J Bundgaard, Aleksndra Fijalkowska, Shintaro Go, Andrew M Keeler, Miguel Madurga Flores, Shree Neupane, Shunji Nishimura, Maninder Singh, Krzysztof P. Rykaczewski An experiment using the VANDLE neutron time of flight detector setup, along with a LaBr3 HAGRiD and clover gamma ray arrays will measure the decay of the 78Ni and neighboring nuclei. This experiment will also include a newly developed YSO implant detector that will allow for a fast beta trigger used in the time of flight calculation. The neutron and gamma detectors allow for the complete measurements of both neutron bound and unbound states in 78Cu. With the decay strength distribution, one can calculate the lifetime for the neutron-rich nuclei in the region of the origin of the r-process. The proposed experiment at RIBF RIKEN is scheduled to occur late 2018, with the VANDLE setup, which is already completed and tested on site. |
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HA.00019: Innovative 238U fission yield evaluation to address the reactor antineutrino puzzle Tunisia Solomon, Elizabeth McCutchan, Alejandro A Sonzogni The antineutrino spectrum from 238U has been singled out by A. Hayes et al. as a likely source of the excess of antineutrinos at 5 MeV with respect to the Huber-Mueller model, colloquially known as ‘the bump’, observed by Daya Bay, Double Chooz and RENO. The current 238U antineutrino reference spectrum was obtained using nuclear databases by Mueller et al., as the quality of the corresponding electron spectra does not allow for a meaningful conversion. In this work, we calculated independent and cumulative 238U fission yields (FY) incorporating new data and modelling tools. Our starting point was the high-resolution mass yields measured at GELINA, obtaining isotopic FY with the assistance of the GEF code and in consultation with yields from the SOFIA experiment. The latest measurements of isomeric ratios were used to obtain independent yields. Finally, cumulative FY were obtained with the latest nuclear structure data. Comparison of the newly calculated FY with recent data as well as a preliminary 238U antineutrino spectrum will be presented. |
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HA.00020: High-Precision γ-ray spectroscopy of the PET imaging agent 72As Emily J Gass, Elizabeth McCutchan, Kathryn McKillop, Alejandro A Sonzogni, R J Nickels, Paul A Ellison, John P Greene, Michael P Carpenter, M Gott, Shaofei Zhu, Christopher J Lister
Radioisotopes are used for imaging or therapeutic purposes in millions of procedures annually. The future of nuclear medicine is to pair a therapeutic agent with a positron emitting isotope to perform simultaneous PET imaging of the therapy agent. One of the most promising new theranostic pairs is 72As. The decay of 72As was last studied in 1971 using a primitive Ge detector system. To provide higher-quality decay data, a source of 72As was assayed at Argonne National Laboratory with the Gammasphere array. This allowed previously-observed cascades to be confirmed and new γ-rays to be identified. The revised level scheme and high-precision intensities will be presented and their impact on the dose of γ and β radiation will be discussed.
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HA.00021: Modernization of the Nuclear Wallet Cards and Homeland Security Booklet Jeami Van Weele, Elizabeth McCutchan, Alejandro A Sonzogni, Timothy Johnson The Evaluated Nuclear Structure Data File (ENSDF) is the world-leading source of nuclear structure and decay data, used for basic science as well as in many applied communities. Commonly used data in ENSDF is regularly printed into two popular booklets, the Nuclear Wallet Cards (NWC) and the Homeland Security Booklet (HSB). The NWC provides the mass, spin/parity, half-life, and decay mode for the ground state and long-lived isomers of more than 3,300 nuclei. The HSB contains data on long-lived radionuclides including half-lives as well as energies and intensities of strong γ and α emissions. In the present work, we developed a new JAVA code to parse ENSDF and generate formatted Latex files to create the printed booklets. We are also developing new mobile applications to allow for quick and easy searches of the data in both booklets. The new codes, along with improvements to searching and viewing the data, will be presented. Expanded versions of the NWC and the HSB will also be unveiled. |
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HA.00022: ENDF/B-VIII.0 library application to nuclear astrophysics Lauren Osojnak, David Alan Brown The Evaluated Nuclear Data File (ENDF/B-VIII.0) is the US recommended library of nuclear reaction cross sections, and thus naturally possesses potential impacts for nuclear astrophysics applications. To facilitate the use of ENDF in various astrophysics applications, the current work uses FUDGE, a program that performs nuclear data testing and processing to translate the ENDF library into an astrophysical reaction rate library format (REACLIB). The present work involved fitting astrophysical reaction rates from ENDF using least squares regression and comparing the fit to the parameterization of rates given by REACLIB. The potential application of the results of this project to nuclear fission experiments such as the Nuclear Ignition Facility as well as astrophysical nucleosynthesis calculations will be presented. |
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HA.00023: Automating the development of a global nuclear reaction data library Kayla Clements, Gustavo P Nobre Simulation and modeling software used for various nuclear science applications - activation, nuclear energy, astrophysics, forensics, etc. - require detailed reaction data in order to make accurate predictions and fill availability gaps in experimental data. Reaction evaluation codes such as EMPIRE fill these gaps by combining experimental results with theoretical models. This project, as part of Brookhaven National Laboratory’s Department of Nuclear Science and Technology, aims to automate EMPIRE runs and generate reliable, self-consistent evaluated files across the whole nuclide chart, including nuclei off-stability. The program, written as a bash shell script, generates and runs EMPIRE inputs with minimal user input. The final script is capable of employing specific reaction models for different nuclide groups, exemplified by the successful application of an adiabatic model to deformed nuclei, and its infrastructure can be easily modified to employ other models across the entire nuclide chart. |
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HA.00024: Mass Measurements of 23Na and Beamline Upgrades for TAMUTRAP Facility Guadalupe Duran, Veli Kolhinen, Dan G. Melconian, Morgan Nasser, Asim Ozmetin, Praveen D Shidling, Benjamin Schroeder The Texas A&M University Penning Trap (TAMUTRAP) facility was designed to test the Standard Model by studying the β+-νe angular correlation parameter of superallowed β-delayed proton decays. Currently, the trap is being commissioned by utilizing stable isotopes to perform precision mass measurements. Using the prototype trap, we performed mass measurements of 23Na by analyzing the time-of-flight and resonance frequency of the ions. We found the mass of 23Na to be 22.989766(12) u which agrees with the literature value within a precision of 1.5x10-7. After performing these measurements, we implemented several upgrades to the hardware of the facility. This included the cleaning, assembling, and installation of a spherical deflector and beam steerer. Additionally, an attempt to realign Section I of the TAMUTRAP beamline was made using an optical transit technique to prepare the Penning trap to receive radioactive beam from the K150 cyclotron. We found that to be fully aligned, we need to shift section II of the beamline as well, which will be done in the Fall. Finally, the new, full-sized Penning trap was cleaned, assembled and preliminary tests were conducted to prepare for its installation. |
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HA.00025: Mass Measurements Using TAMUTRAP and Upgrades to its Control System Cristhian Eduardo Gonzalez Ortiz, Veli Kolhinen, Dan G. Melconian, Morgan Nasser, Asim Ozmetin, Praveen D Shidling, Benjamin Schroeder The TAMUTRAP facility, located in the Cyclotron Institute at Texas A&M University, is based on a novel, large-diameter cylindrical Penning trap where radioactive ions are confined. The main objective of this experiment is to test the Standard Model by making precise measurements of the β-ν angular correlation parameter on several isospin T=2 super-allowed proton emitters (e.g. 32Ar). In order to efficiently load the ions into the Penning trap, a radio frequency quadrupole (RFQ) gas cooler and buncher is used. The following work focuses on the calibration process used in order to remotely control the pressure of the gas cooling system and several high voltage power supplies used throughout the beamline. Several LabVIEW VI's were designed for this purpose. Additionally, the mass of 23Na was measured relative to 39K to demonstrate the mass-measurement capabilities of TAMUTRAP. The measured mass of 23Na was 22.989774(11) u, which agrees with the literature value within a precision of 1.9×10-7. |
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HA.00026: Study of 22Ne(6Li,t)25Mg three particle transfer reaction using TIARA and MDM spectrometer. Esha Rao The (6Li,t) transfer reaction serves as a powerful tool to study 3He clustering states. Furthermore, for N=Z target nuclei (6Li, t) and (6Li, 3He) are expected to populate mirror states in the resulting recoil nuclei, due to the strong 3He + 3H clustering property of 6Li. There is also potential to study nuclear structures by three particle transfer, e.g., using a radioactive ion beam, which can be a useful method for nuclear astrophysics. The 22Ne(6Li,t)25Mg experiment was performed in inverse kinematics using a 7A MeV 22Ne beam and 6LiF target at the Texas A&M University Cyclotron Institute. To better understand (6Li,t) three particle transfer reaction, measurements of 25Mg, t, and gamma-rays were made in coincidence using a magnetic spectrometer, Si, and Ge detectors. By doing this, the populated states of 25Mg were clearly identified thus enabling an understanding of the reaction selectivity. The angular differential cross sections were then measured to extract the spectroscopic factors. The results of this 22Ne(6Li,t)25Mg analysis were compared with data from other reaction methods and theoretical calculations to improve the knowledge about the 22Ne(6Li,t)25Mg reaction. |
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HA.00027: Sensitivity of Electric Dipole Polarizability to Bulk Nuclear Properties Ethan Hunt, Giacomo Bonasera, Shalom Shlomo The electric dipole polarizability, αD, has been considered in the literature to be sensitive to the neutron skin Δrnp and to the density dependence of the symmetry energy J = J(ρ). We carry out a detailed investigation of the sensitivity of αD to: J(ρ) and its derivatives evaluated at the saturation density ρ0 as well as other bulk nuclear matter (NM) properties, and neutron skin. We use the Hartree-Fock based random phase approximation to calculate strength function of the isovector dipole resonance for 40,48Ca, 68Ni, 90Zr, 120Sn, 208Pb, and calculate αD, which we compare to experimental results. We also determine the Pearson linear correlation coefficients between αD and NM properties. Our calculations were carried out using 33 Skyrme type interactions with wide ranges of values for NM properties. We determine approximate bounds on the values for certain NM properties. |
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HA.00028: Coherent Dilepton Pair Production in Heavy Ion Collisions at RHIC and SPS Energies John Thomas, Joseph Atchison, Ralf F Rapp An excess of dilepton pairs has been measured in high-energy heavy-ion collisions at very low transverse momentum. These dileptons cannot be explained with modern models of the thermal radiation from the Quark-Gluon Plasma and hadronic matter. This excess is a strong indication of photon-photon interactions prior to the collision. Current models of photon interactions deviate from experimental data at lower dilepton masses. To investigate the discrepancy, we will present new calculations describing the production of coherent dileptons from photon interactions in peripheral Indium-Indium collisions at SPS energies. These calculations will explore in this reaction the excess of dileptons in the lower mass region. |
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HA.00029: TDHF Calculation of 238U+232Th at 7.5 MeV/nucleon Ian Jeanis, Aditya Wakhle, Sherry Yennello To date, all known superheavy elements have been synthesized using heavy-ion fusion reactions, and are neutron poor. For the past three decades, multinucleon transfer reactions have been studied as an alternative to producing more neutron rich super heavy elements. To complement the understanding of multinucleon transfer, Time Dependent Hartree Fock (TDHF) was applied to a 238U+232Th reaction. This reaction has previously been explored experimentally at Texas A&M University by S. Wuenschel et al. In the present work TDHF was used to evaluate 238U+232Th collision at ELab= 7.5 MeV/nucleon. The reaction was explored with prolate deformed nuclei in three distinct orientations: parallel (aligned) and perpendicular (anti-aligned) to the beam axis. Information regarding outgoing angle, mass, and charge in the exit channel and contact time were extracted from the TDHF calculations. The 238U+232Th reaction displayed the greatest mass exchange when the reactants had deformation axes aligned and anti-aligned configurations with respect to the beam axis. |
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HA.00030: Dynamical Fragment Formation in CoMD Simulations Bryan Harvey, Andrea Jedele, Alan McIntosh, Mike D Youngs, Sherry J Yennello Previous experimental results have shown a relationship between fragment alignment and composition in heavy ion collisions. It is proposed that the post-collision excited dinuclear projectile-like-fragment (PLF*) rotates for some time until it dynamically splits, at which point neutron-proton equilibration and rotation would simultaneously cease. This mechanism implies a relationship between these fragments' angular alignment, composition, and the contact time between the heaviest and second heaviest fragments before the PLF* breakup. In order to understand these relationships, Constrained Molecular Dynamics (CoMD) simulations were run using 70Zn+70Zn collisions at 35 MeV/nucleon. We focus on events with the lighter fragment having Z=4, and the heavier fragment having Z≥11. Visualization tools were developed for event-by-event analysis to better understand the mechanisms predicted in the model. As predicted, correlations between contact time, fragment alignment, and composition were observed. |
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HA.00031: Using PIXE and PIGE for Elemental Composition Analysis Elysia Yvette Salas, Alis Rodriguez Manso, Jerome Gautheir, Sherry J Yennello PIXE (particle induced x-ray emission) and PIGE (particle induced gamma-ray emission) are complementary ion beam analysis (IBA) techniques used to study elemental composition. Using 1 µCi of 133Ba, 57Co, and 241Am, the calibration of two detectors: CdTe (x-ray and -ray detector) and Si-PIN (x-ray detector) were conducted. To identify unknown photopeaks observed by the CdTe detector, an energy (keV) versus atomic number (Z) curve was established through the spectral analysis of 29Cu, 73Ta, 50Sn,35Br, 57Co, and 133Ba. Upon completion of the calibration of both detectors, four samples were analyzed in air and vacuum using a 9.5 mCi 241Am alpha source to excite the x-rays on each sample. Based on the background, the limits of detection were computed and the samples were analyzed for the presence of Fe and Ni in a sample, success in eradicating Al from a raw versus treated sample and identification of O in a carbonized sample. In addition, an analysis of a PIGE experiment performed with the K150 cyclotron at Texas A&M using a 3.6/6.3 MeV proton beam was conducted to study the presence and concentration of fluorine in consumer products. |
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HA.00032: Using Machine Learning to Improve Gamma-Neutron Discrimination in P-terphenyl and 6Li Glass Detectors Sophia Andaloro, Grigory V Rogachev, Joshua Hooker Developing reliable neutron-gamma pulse shape discrimination (PSD) methods for scintillator detectors is important for fundamental science and modern security applications. Traditional PSD approaches are inadequate for low energy particles. We developed and optimized machine learning methods to overcome these energy limitations and to improve neutron-gamma separation. We sought to classify these particles using an artificial neural network (ANN) and visualize neutron-gamma separation using dimensionality reduction methods. To create training and testing data sets, p-terphenyl crystal and 6Li glass detectors were used to detect isolated gammas, fast neutrons (p-terphenyl) and thermal neutrons (6Li glass). The data was then used to optimize the ANN, which consisted of a non-sequential model for binary classification. Dimensionality reduction techniques were used to visually separate neutrons and gammas. We discuss the accuracy of the ANN in identifying neutrons and gammas over the incident energy spectrum and present the dimensionality reduction methods which yielded distinct neutron-gamma separation. |
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HA.00033: Bayesian Modeling of the PSR J0737-3039A Moment of Inertia Robert Stahulak, Jeremy Holt Neutron star observations have the potential to strongly constrain models of the nuclear equation of state. In the near future, precise measurements will be made of the moment of inertia for several known neutron stars. The purpose of this work is to make predictions to further constrain the parameters of the dense matter equation of state using these measurements. To this end, we will calculate neutron star moments of inertia for a wide class of equations of state already constrained by many-body theory and empirical data. The neutron star moment of inertia will be derived from numerical solutions of the Tolman-Oppenheimer-Volkov (TOV) equations assuming a symmetric fluid body with corrections for general relativity using a slow-motion approximation. Comparisons were made with a prior determination of the mass of the binary pulsar PSR J0737-3039A. |
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HA.00034: Designing Dichroic Filters For Use In A Microwave Camera to Study Electron Cyclotron Resonance Ion Sources Sarah Peery, L. E. Henderson, Carl Albert Gagliardi The Electron Cyclotron Resonance (ECR) ion sources in use at many laboratories, including the Texas A&M University Cyclotron Institute, are well understood in their function, but better diagnostics are needed to study the details of ECR plasma dynamics. Previous studies have primarily focused on investigating the positive ions in the source. In contrast, our goal is directly to image the electrons that produce the ionization, in order to optimize the production of higher intensity and charge state beams. A microwave camera sensitive in the 15-65 GHz range is being designed to measure the Electron Cyclotron Emission from the plasma. The camera will include a set of dichroic filters to prepare the signal for reception by the antenna array and superheterodyne receiver electronics. The dichroic filters will be made up of arrays of aperture antennas and designed to switch electronically between passbands with 10 GHz bandwidths. This work explored potential designs and optimized various array geometries via MEEP, an electromagnetic simulation software that uses the finite-difference time-domain method, and a hill climbing algorithm. |
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HA.00035: Precise Measurement of $\alpha_K$and $\alpha_T$ for the 39.8-keV E3 $\gamma$ transition into $^{103}$Rh $\beta^-$ decay to Improve the Internal Conversion Theory Xavier K James, Dr. Ninel Nica, Dr. Hyo-In Park, Dr. John Hardy Our goal is to distinguish the two versions of the internal conversion theory, one which ignores the atomic vacancy left behind from the emitted electron and another that takes the vacancy into account. Spectra were recorded with an HPGe detector was calibrated to a precise efficiency of about ± 0.15% relative uncertainty. In the acquired spectra, the impurities of the 103Ru source were properly analyzed and amended based on the energy and areas of the γ -ray peaks using MAESTRO-32 and the Evaluated Nuclear Structure Data File database. The more precise gf3 γ-ray analysis software further used to get the precise peak areas of the intense transitions of 103Rh to get the clean areas of the 20.6-keV Rh K x-rays and the 39.8-keV γ -ray used to extract the experimental value of the . In comparison to the theoretical calculations, our preliminary result, although not in agreement with both theoretical calculations, is much closer to the hole “frozen orbital” limit but in clear disagreement with the “no hole” limit in accordance with the previous results. More experiments are required to further improve upon the internal conversion theory with taking into account the vacancy left by the atomic electron. |
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HA.00036: Production of 149Terbium for Medical Diagnostics and Treatment Mallory McCarthy, John Wilkinson, Sean McGuinness, Shaun Loveless, Sam Ferran, Suzanne Lapi, Graham F Peaslee Long-lived radioactive isotopes are used for applications such as cancer diagnostics and treatment. These isotopes must typically satisfy several criteria to be suitable – such as having an appropriate half-life and specific decay properties. We produced 149Tb (t1/2 = 4.1 hrs) by an indirect heavy ion reaction, 141Pr(14N, 6n)149Dy, which subsequently decayed to 149Tb. A 10 MeV/n 14N beam was accelerated by the K150 Cyclotron at Texas A&M University’s Cyclotron Institute and irradiated a Pr6O11 target. The long-lived products produced in this reaction were identified by gamma-rays with a high-purity germanium detector set to measure off-line in one-hour increments over 22 hours. This information was used to measure the original activity of 149Tb at the end of beam and to calculate the reaction cross section. The observed cross section is significantly lower than the theoretical cross section, although this difference has been seen previously in the literature. |
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HA.00037: Using Particle-Induced Gamma-Ray Emission Spectroscopy to Detect Fluorinated Substances in Personal Care Products Emi Eastman Per- and polyfluoroalkyl substances (PFASs) are known environmental contaminants linked to cancer and other adverse health effects. These compounds have applications in a wide variety of products, including personal care products. PFASs in cosmetics—specifically mascara and lipstick — can travel into the eyes and mouth and increase chances of human exposure. We measured total fluorine in 235 cosmetics using particle-induced gamma-ray emission (PIGE) spectroscopy. PIGE offers an efficient technique to detect the presence of fluorine involving minimal analysis time compared to traditional methods. We found that 54% of all the cosmetic samples contained fluorine, including 92% of waterproof mascaras and 80% of liquid lipsticks. A subset of 8 samples are currently being sent to our collaborators at Oregon State University to identify which fluorinated compounds are in our samples. |
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HA.00038: Proton Induced X-Ray Emission (PIXE) Analysis to Measure Trace Metals in Soil Along the East River in Queens, New York Sajju Chalise, Scott LaBrake, Michael Vineyard The Union College Ion-Beam Analysis Lab’s 1.1 MV tandem Pelletron accelerator is used to determine the presence of heavy trace metals in Queens, NY between Astoria Park and 3.5 miles south to Gantry State Park. A PIXE analysis was performed on 0.5 g pelletized soil samples with a 2.2 MeV proton beam. The results show the presence of elements ranging from Ti to Pb with the concentration of Pb in Astoria Park (2200 ± 200 ppm) approximately ten times that of the Gantry State Park. We hypothesize that the high lead concentration at Astoria Park is due to the nearby Hell Gate Bridge, painted in 1916 with lead based paint, then sandblasted and repainted in the ’90s. To test this, soil samples were collected and analyzed from different locations north and south of the bridge. The concentrations of lead decreased drastically within a 500 m radius and were approximately constant at greater distances south the bridge. More samples need to be collected to identify the potential source of Pb. We will describe the experimental procedure, the PIXE analysis of soil samples, and present preliminary results on the distribution of heavy trace metals.
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HA.00039: Using HECTOR for Cross Section Measurements of 102Pd(p,g)103Ag Emily Churchman, Anna Simon, Orlando Gomez, Rebeka Kelmar, Craig Reingold, Sean Kelly The High EffiCiency TOtal absorption spectrometeR (HECTOR) consists of 16 scintillating crystals that are made of thallium-doped sodium iodide (NaI(Tl)). Each of the crystals is coupled to two photomultiplier tubes (PMT) and the detector is oriented to create a cubic array surrounding a target. This cubic array orientation allows for simultaneous measurements of the individual gamma (γ) rays produced during the de-excitation of the reaction products, creating a coverage of nearly 4π steradian. HECTOR was constructed to measure capture reactions relevant for the nucleosynthesis process at low energies. The work presented here focuses on a (p,γ) reaction on 102Pd, one of the p-nuclei produced during the p-process. The experiment was conducted at the University of Notre Dame using the FN tandem accelerator at the Nuclear Science Lab. A highly enriched 102Pd target was bombarded with a proton beam at energies between 3.5-8 MeV in 200 keV steps. The measured cross section is compared with experimental data found in literature and theoretical models. |
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HA.00040: Limitations in the Study of Cultural Heritage Objects With Atomic Spectroscopy Cecilia Fasano, Khachatur Manukyan, Ashabari Majumdar, Graham F Peaslee, Edward Stech, Michael Wiescher The study of cultural heritage objects, such as coins, using techniques from nuclear physics including x-ray fluorescence (XRF) and proton induced x-ray emission (PIXE) has been in practice for many years. These methods have been used because of their non-destructive nature, but this gentleness comes with a set of important challenges. The limitations of these methods, such as silver surface enrichment and inconsistency between analysis techniques, have been previously characterized and are well documented. A challenge that is less well documented is that of surface inconsistency. In this study, XRF, PIXE, and EDS were used on a set of 20 Ancient Roman Denarii to qualify and quantify this surface level inhomogeneity. Data were taken using varying beam sizes and at varying locations in an attempt to provide the most complete view of each sample. Data from small spots were then compared with large-scale XRF maps of each coin. It was concluded that researchers should be concerned with both the cross-sectional inhomogeneity and surface inconsistency. The addition of surface analysis will allow researchers to most fully contribute to the dialogue about how physical objects are woven into cultural history. |
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HA.00041: Development and Characterization of Magnesium Targets Kristin Ringhand, Michael Wiescher, Khachatur Manukyan, Richard J DeBoer, Kevin T Macon A set of natMg targets were designed and characterized in preparation for a longer investigation of the 26Mg (α, n) reaction as a potential neutron source for the stellar s-process. Targets were prepared on a variety of backings---including tantalum, silicon, copper, and carbon film---to increase the range of characterization techniques available. Evaporations were conducted with pure magnesium and as a reduction of magnesium oxide. Alpha spectroscopy, microscopy analysis, and energy-dispersive X-ray spectroscopy were used to characterize the target runs, which had been varied in evaporation speed, target thickness, and technique. Due to the variety of characterization methods available, analysis yielded information about grain size, deposition patterns, target thickness, and elemental content. Notably, targets which had been evaporated more slowly were more uniform in terms of both grain size and thickness. Targets will be subjected to further testing to determine their structural integrity under beam. This information will then be used to select the best targets for the ongoing 26Mg (α, n) investigation. |
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HA.00042: TROPIC: A New Code for Calculating Absolute Transition Probabilities Using Python and Mathematica Anne K Stratman, Clark R Casarella, Ani Aprahamian Absolute transition probabilities serve as a cornerstone for nuclear structure studies, by providing a measure of the collectivity of a particular transition and the matrix elements that connect the states of interest. We have developed Python and Mathematica versions of a program, named TROPIC (Transition Probability Calculator), for calculating absolute transition probabilities. Both versions take quantities such as the lifetime of a state, energy and intensity of the emitted γ-ray, and multipolarities of transitions to calculate B(σλ) values. TROPIC allows for the inclusion of mixing ratios of different multipolarities and the electron conversion of γ-rays, and provides results in e2bλ or results normalized to W.u. We have tested this code against TRANSNUCLEAR [1], and will present transition probabilities calculated for 156Gd using data from GRID measurements and for 158Gd using data from an (n,n′γ) reaction as a comparison. Both versions, along with sample input and output files and user guides, will be available for download on the University of Notre Dame’s Nuclear Science Laboratory webpage. |
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HA.00043: Interpolation of odd beta-decay rates from even-even theoretical rates for nucleosynthesis applications Andrew M Toivonen, Rebecca A Surman, Trevor M Sprouse Beta decay rates, particularly those furthest from stability, are an essential part of nucleosynthesis calculations for extreme, super-massive stellar events. For such nuclei, however, experimental data is sparse and theoretical models are inconsistent with one another. In this theoretical and computational project, we started with the even-even beta decay rates of Mustonen and Engel and generated eight different sets of predicted odd-even, even-odd, and odd-odd beta decay rates. Some of the data sets we generated relied on theoretical data, some on experimental data, and others a combination of the two. When possible, the predictions were optimized to be the most accurate away from stability: in the region of sparse experimental data. We then investigated the impact of the different interpolations on abundance patterns from nucleosynthesis calculations run under four different initial conditions. |
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HA.00044: A Proposal for Experimentally Measuring the 35Cl(3He,2p)36Cl Cross Section: Early Solar System Irradiation Effects on Short-Lived Radioisotope Production Connor Alexander Williams, Philippe Collon, Tyler Anderson Short-lived radioisotopes (SLRs) with half-lives ~ 100 Ma are known to have existed during the formation of the solar system around 4.5 billion years ago through the detection of their decay products in meteorites. Freshly synthesized SLRs are believed to have been injected into the Giant Molecular Cloud from which the sun was formed, by a nearby stellar source (e.g. supernovae). The concentration of the decay products of 36Cl exceed their expected enrichment levels, suggesting that a secondary source may be responsible for the excess. Solar energetic particles from the sun may have irradiated gas and dust present in the solar accretion disk, aiding the accumulation of SLRs in chondrules and Ca-Al rich inclusions. Experimental data is needed in order to validate the solar irradiation model, and therefore, the cross sections of the nuclear reactions in question must be measured. The cross section of the 35Cl(3He,2p)36Cl reaction was estimated in order to evaluate the feasibility of creating the reaction in a laboratory setting. Based off of cross section predictions, seven activation energies within the range of 1.44 MeV/A to 2.51 MeV/A are proposed for future measurement. |
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HA.00045: Rare-Earth Thin Film Target Preparations and Techniques for (p,t) Reactions Leah M. Clark, Shelly R. Lesher, Ani Aprahamian, Khachatur Manukyan Accelerator based low energy nuclear physics can provide great insight into the structure of nuclei. The search for 0+ states in the rare-earth region via the (p,t) reaction has revolutionized nuclear structure by the discovery of numerous 0+ states below the pairing gap. This was made possible with the high precision Q3D spectrometer at the Maier-Leibnitz Laboratory in Germany. Our aim is to explore and complete the studies of 0+ states in the deformed rare earth region of nuclei on the chart of nuclides. A particular challenge lies in making targets for the experiments. At the University of Notre Dame the lanthanides, Erbium-168, Dysprosium-162, Ytterbium-174, and Ytterbium-176, were experimented on to create the best thin film targets for this experiment. A bell jar evaporator and electron beam evaporator were used for the low and high temperatures lanthanides, respectively. The challenge was in the deposition of the high temperature lanthanides. In time, the procedure worked and multiple targets were created for the experiment. The different techniques, how the targets performed, and preliminary experimental results will be presented. |
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HA.00046: Application of GEANT4 for Efficiency Modeling of an Implantation Detector System used in Beta-Decay Studies of Exotic Nuclei Dylan Smith, Benjamin Crider, Timilehin Ogunbeku, Yongchi Xiao, Katherine L Childers, Partha Chowdhury, Edward Lamere, Rebecca Lewis, Sean N. Liddick, Brenden Longfellow, Stephanie Lyons, Shree Neupane, David Perez Loureiro, Christopher J Prokop, Andrea L Richard, Umesh Silwal, Durga P Siwakoti, Mallory K Smith Beta decay is a highly sensitive and selective means for assessing the properties of exotic nuclei when there are only a small number of atoms available for study. One method of performing beta decay studies involves the implantation of radioactive ions of exotic nuclear species directly into a detector. Following implantation and subsequent decay, event by event reconstructions using spatial and temporal information allow for the unique identification of the parent and daughter decays. A feature of performing beta decay studies using an implantation detector is that one cannot determine the absolute efficiencies of the detectors via source measurements alone. Instead, source measurements must be reproduced in simulation where the origin of the source is moved physically inside the detector in order to reproduce the experimental conditions for implantation. A new CeBr3 implantation scintillator was utilized in a recent beta decay experiment at the National Superconducting Cyclotron Laboratory that was performed in July, 2018. Efforts are underway to simulate the efficiencies and response of the CeBr3 detector and ancillary LaBr3 and high-purity Germanium detection systems used. Preliminary results modeling the systems and a NIST-calibrated 154,155Eu source will be presented. |
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HA.00047: Fitting turbulent and convective parameters in one-dimensional core-collapse supernova simulations Theo Eckler Cooper, Brandon Barker, Jennifer Ranta, Michael Pajkos, MacKenzie Warren, Brian O'Shea, Sean Couch Core-collapse supernovae (CCSNe) are the explosive deaths of massive stars. While CCSNe are crucial to many aspects of our understanding of the universe, including the synthesis of the elements, the physical mechanism that drives these explosions is not fully understood. While three-dimensional simulations of core-collapse supernovae are the most physically accurate representation of the real phenomenon, they use a notorious amount of computing power. 1D simulations are less demanding but fail to reproduce many of the physical effects of 3D calculations. We propose that, by including the proper coefficients of turbulent diffusion and convective mixing length in our model, 1D simulations can be executed in a way that reproduces the results of 3D simulations. If successful, this method could potentially allow for faster, equally accurate testing of future hypotheses. In this study, we construct a Gaussian Process Emulator of the parameter space and use Markov Chain Monte Carlo methods to find optimal values for the mixing-length coefficient αΛ and diffusion coefficient αD. Once αΛ and αD are found empirically, they will be used to close the model equations governing the turbulent dynamics in 1D simulations of CCSNe during the period immediately following core bounce. |
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HA.00048: Effects of Input Nuclear Physics on Core Collapse Supernova Simulations Brandon Barker, Theo Cooper, Michael Pajkos, Jennifer Ranta, MacKenzie Warren, Sean Couch In the proto-neutron star formed during a core collapse supernova (CCSN), densities can reach several times nuclear density. Due to uncertainties in nuclear physics, there are several different physical models for the equation of state (EOS) at the densities present in the CCSN environment. The outcomes of CCSN simulations can depend sensitively on the EOS. 1D CCSN simulations are key in predictions of the outcome of stellar evolution, neutron star mass distribution, nucleosynthesis, and ultimately, galactic evolution. However, uncertainties in nuclear physics causes changes in these results: simulations using different EOS tables can lead to entirely different predictions. We explore the sensitivity of CCSNe to variations in input nuclear physics. Using 10 different EOS models, we ran 1D CCSN simulations with progenitor masses ranging from 9 to 120 solar masses using a new model for driving 1D explosions that includes the crucial effects of turbulence and convection. A quantitative understanding of how different EOS tables affect the outcome of core collapse is crucial to our ability to make predictions. |
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HA.00049: SECAR: The Separator for Capture Reactions in Nuclear Astrophysics Aalayah Spencer, Sara Ayoub The SEparator for CApture Reactions (SECAR) is a recoil separator currently under construction at the National Superconducting Laboratory (NSCL) and the Facility for Rare Isotope Beams (FRIB). It will be dedicated to measuring the reaction rates of astrophysically relevant capture reactions on isotopes of mass 15 to 65. SECAR consists of 8 dipoles, 15 quadrupoles, 3 hexapoles, 1 octopole and 2 Wien filters with stringent performance conditions. This presentation will focus on the methods and tools used to optimize beam transport and tuning through the separator. The magnet acceptance procedure used to ensure that the magnets that make up SECAR will be able to perform at the desired specifications, including testing for magnetic field reproducibility, will also be presented. |
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HA.00050: Timing characterization and coincidence measurements with C7LYC n/𝛾 scintillators Joseph Dopfer, Andrew M Rogers, Peter C Bender, Partha Chowdhury, Michael Giles, Edward Lamere, Christopher Morse, Sanjanee W Waniganeththi Fast-neutron detection and spectroscopy is important for both basic and applied Nuclear Science. Inorganic 7Li-enriched Cs27LiYCl6:Ce (C7LYC) scintillation detectors are an emerging technology that provide unprecedented (≈10%) energy resolution for fast neutrons in the few MeV range, obtained through the 35Cl(n,p) reaction. Additionally, the scintillators are sensitive to gamma rays, having an efficiency and energy resolution similar to NaI. Superior pulse-shape discrimination properties enable extremely clean identification of neutron and gamma events. Coincidence measurements using both sources and nuclear reactions generated with a 5.5-MV Van de Graaff accelerator are being carried out at UMass Lowell to further explore their potential. An overview of C7LYC digital pulse-shape analysis techniques and measurements characterizing coincident timing between multiple detectors will be presented. |
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HA.00051: Measuring Beta Decays of Proton-Rich Nuclides to Study Explosive Nucleosynthesis Tamas Budner, Marco Cortesi, Moshe Friedman, Cathleen E Fry, Brent E Glassman, Madison Harris, Joseph Heideman, Molly Janasik, David Perez-Loureiro, Emmanuel Pollacco, MIchael J Roosa, Jordan Stomps, Jason Surbrook, Pranjal Tiwari, Christopher Lars Henrik Wrede, John Yurkon Our team has developed a system to detect radiation associated with the beta decays of proton-rich nuclides at the National Superconducting Cyclotron Laboratory. The experimental data acquired will be applied to the field of astrophysics, specifically to the rates of nuclear reactions driving explosions on the surfaces of accreting white dwarf and neutron stars in binary systems. The detection system consists of a custom designed gas-filled charged-particle detector surrounded by the existing Segmented Germanium Array for gamma-ray detection. To complement the detector, a data acquisition and display system is required. The capability to monitor the online data is essential so that researchers can make decisions based on preliminary analysis as data arrives. Using an in-house software called SpecTcl, we have utilized experiment specific traits to customize a system for acquisition and analysis. This detector was successfully commissioned at NSCL in May 2018, and is ready for science experiments. The SpecTcl system was used to sort and display the online data during commissioning. |
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HA.00052: Detailed Characterization and Optimization of β-Delayed Proton Detector Molly Janasik, Moshe Friedman, Chris Wrede In order to determine the rates of two important reactions for the astrophysical rapid proton (rp) capture process, a segmented, low background β-delayed proton detector has been built at NSCL. Detailed characterizations of the detector’s Micromegas pad plane and gating grid have been performed using measurements with a radioactive 55Fe x-ray calibration source and 220Rn alpha source, respectively. Fitting routines have been developed to extract the energy resolutions from the spectra. Results of detector performance will be presented. |
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HA.00053: An exploration into Neutron Sensitivity Maya M Watts, Stephanie M Lyons, Artemis Spyrou Studying nuclear properties is useful for getting a better understanding of the nuclear processes that occur in stars. These stellar nuclear processes are responsible for forming the known elements in the universe. At the National Superconducting Cyclotron Laboratory, the Summing NaI detector, SuN, is used to measure various probabilities of capturing a particle. These reaction probabilities are referred to as capture cross sections. SuN is a large volume scintillating detector made of NaI crystals. It is used to observe gamma rays from various nuclear reactions being studied. However, in addition to the gamma rays, reaction data shows that SuN may also have some neutron sensitivity. This neutron sensitivity is what is being examined in this project. It is being investigated through simulation and comparison with experimental data to determine the neutron information that we can extract from SuN data. Studying the neutron sensitivity of SuN is useful for verifying and developing a deeper understanding of past and future experimental data used for studying stellar processes |
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HA.00054: Inverse-Kinematics Proton Scattering on 44S M. A. Liggett, L. M. Skiles, S. D. Gregory, E. B. Haldeman, B. R. Klybor, L. A. Riley, D. Bazin, R. G. T. Zegers, Peter C Bender, Paul Davis Cottle, Brandon Elman, Alexandra Gade, Kirby W Kemper, Samuel Lipschutz, Brenden Longfellow, Eric Lunderberg, Tea Mijatovic, Jorge Pereira, Rachel C T Titus, Dirk W Weisshaar, J. C. Zamora, R. G. T. Zegers Using data from an inverse-kinematics proton scattering experiment that took place at the National Superconducting Cyclotron Laboratory (NSCL) in Michigan State University we study the excited states of 44S using the NSCL/Ursinus College liquid hydrogen target and the Gretina gamma-ray tracking array. We report the proton-scattering deformation length of the 2+1 excitation in 44S and discuss the results in the context of similar experiments on neutron-rich sulfur isotopes. |
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HA.00055: High Voltage Electrode Conditioning for use in the Measurement of the Permanent Electric Dipole Moment of Radium-225 Peyton Alexandra Lalain An electric dipole moment (EDM) is an observable indication of time reversal symmetry violation, new sources of which are needed to explain the dominance of matter over antimatter in the universe. Due to its pear-shaped nucleus, the 225Ra atom has an increased sensitivity to this violation. To search for an EDM, we measure the difference in the clock rate under reversal of the electric field with respect to the magnetic field. A uniform and stable electric field is applied to an ensemble of 225Ra atoms in order to measure its EDM. Our immediate goal is to improve the electric field by a factor of three, and by more than a factor of 10 in the long term. We do this by conditioning round Nb electrodes to remove microscopic imperfections. Our progress is measured by monitoring the electrodes for discharges and a steady state leakage current as we increase the potential difference. We started with electric fields of ±10 kV/mm, and have been able to validate ±20 kV/mm, with a long term goal of ±100 kV/mm, as produced in previous experiments. |
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HA.00056: Reducing Background in Laser Spectroscopy Experiments at BECOLA Hannah Olds, Kei Minamisono, Jeremy D Lantis, Andrew J Miller, Skyy V Pineda, Robert Powel, Joel Zuzelski A discontinuity is generally observed in trends of mean-square charge radii at the magic numbers. The discontinuity, however, is missing at the N = 20 neutron magic number for Ar, K and Ca isotopes. The trend of Sc charge radii across N = 20 is therefore of great interest, as it will show the effect on the missing signature caused by one proton in the 1f7/2 shell outside the 40Ca core. As a preliminary step towards the investigation, a hyperfine spectrum of stable 45Sc was studied using collinear laser spectroscopy techniques at BECOLA at NSCL/MSU to optimize the laser spectroscopy system. Details of test measurements and results will be discussed. |
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HA.00057: Advancements and characterization of Low Energy Neutron Detector Array (Large LENDA) Alyssa Davis, Remco G.T. Zegers, Jaclyn M Schmitt, Sam M Austin, Daniel Bazin, Alex Carls, Miles DeNudt, Bingshui Gao, Shumpei Noji, Jorge Pereira, Rachel Titus, Juan Carlos Zamora The study of charge-exchange reactions is important to understand the spin and isospin structure of nuclei, which allows researchers to improve nuclear models. An upcoming experiment at the National Superconducting Cyclotron Laboratory will use the 12N(p,n)12O charge-exchange reaction to study the structure of 12O. This is the first (p,n) experiment on a proton-rich unstable nucleus, and results will provide techniques to study heavier proton-rich systems, ultimately up to the region near 100Sn. The reaction kinematics will be reconstructed from the energy and angle of the ejected neutron. The neutron is detected by the Low Energy Neutron Detector Array (LENDA), a set of twenty-four 30 cm-long plastic scintillators. To improve neutron detection efficiency, large 150 cm-long plastic scintillators will be added to LENDA. To ensure uniform detection capabilities across all new detectors, several characterization tests were carried out. These included light leak reduction, attenuation length measurement, optimum bias determination, gain matching, energy/position calibrations, and timing resolution measurements. Methods and results of the characterizations will be discussed. |
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HA.00058: Developing a Rutherford Backscattering Spectrometry Station for TUNL Andrew Wantz Rutherford backscattering spectrometry (RBS) is a technique used to characterize solids via surface- |
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HA.00059: Optimization of Particle Energy and Arrival Time Determination using GPUs for the Nab Experiment David Perryman Measurements of neutron beta decay correlation parameters yield a ratio of axial and vector weak couplings as well as test physics beyond the Standard Model. The Nab (Neutron a b) experiment will extract these parameters by coincidence detection of beta decay's protons and electrons, which includes energy and time of flight determination. Because of the experiment's expected high data throughput in the form of digitized waveforms from pixelated silicon detectors, it is important to extract energies and times quickly and reliably. This poster will present results from timing and statistical studies using graphics processor based energy and time extraction. |
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HA.00060: Neutrino Physics with PROSPECT Background Characterization at the High Flux Isotope Reactor (HFIR) Diego Venegas Vargas, Alan Salcedo, Alfredo Galindo-Uribarri The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) is a neutrino experiment at short baselines that aims to search for the existence of sterile neutrinos and precisely measure the energy spectrum of antineutrinos emitted from the Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR). A complete characterization of background sources present throughout the course of the experiment is required to obtain a proper understanding of the reactor’s response, as well as to investigate the variation of background during operation periods. The PROSPECT detector has been collecting data since March 16th of the present year. This study presents data obtained through measurements and simulations of the background sources at HFIR, along with preliminary results of the detector’s performance. A brief overview of the detector’s status and main physics goals are presented.
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HA.00061: A Mirror World? Detector Background Measurements for a Mirror Neutron Regeneration Experiment Alexander Patrick Blose, Leah J Broussard, Christopher B Crawford There may exist a hidden mirror gauge sector with a complete copy of our normal gauge sector, standard model matter. This so-called mirror world would interact only weakly through the gravitational force, making it a candidate for dark matter, and may allow neutrons to oscillate. An experiment to search for neutron oscillations will take place at Oak Ridge National Laboratory’s High Flux Isotope Reactor (HFIR) using the General Purpose-Small Angle Neutron Scattering (GP-SANS) instrument and its low background Linear Position Sensitive Detectors (LPSD). We used a separate LPSD to characterize the sources of neutron backgrounds in the vicinity to determine the necessary shielding requirements for the GP-SANS detectors from backgrounds from cosmogenic sources or other instruments. We will present results of the detector characterization, comparison to the GP-SANS detector performance, and background studies at GP-SANS. |
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HA.00062: Determining the Energy Resolution of BGO Scintillator Crystals as a Detector for ProRad Justin T Dickovick In an attempt to further understand the Proton Radius Puzzle, the ProRad experiment at IPN Orsay seeks to measure the electric form factor of the proton with a much higher precision than before. To do this, they must construct a detector capable of taking precise enough measurements. The purpose of this project was to test Bismuth Germanate Oxide (BGO) crystals from two different manufacturers to use as a scintillator detector. Additionally, two different light insulations for the crystals were tested. Using a 137Cs radioactive source, the energy deposit spectrum of the crystal was measured and used to determine the energy resolution of the crystals. Using this method, the energy resolution was measured at different points along the crystal to make sure that the resolution was independent of where the radiation hit the crystal, an important trait for them to have. The findings will provide ProRad with insight on the optimal crystal to build their detector with and will also provide an experimental setup to quality test the crystals that they order for the detector. |
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HA.00063: Semiclassical Simulation of Spin Evolution in the UCNτ Experiment Jeremiah Ginder The free neutron lifetime τn is a β-decay observable used in Big Bang Nucleosynthesis predictions of light element abundances, and along with other β-decay observables allows testing of the unitarity of the CKM matrix. The goal of the UCNτ experiment is to measure τn with a maximum uncertainty of 0.01%. The experiment uses a bowl-shaped, permanent magnet Halbach array within a vacuum jacket to hold low-field-seeking, ultracold neutrons (UCN). To achieve a high precision, UCN must not leave the trap for reasons other than β-decay, such as depolarization. Depolarization is when UCN become high-field-seeking and get sucked into the magnets rather than repelled by them. To minimize depolarization, the vacuum jacket is surrounded by coils that produce a magnetic holding field. Two simulations were developed to model UCN spin dynamics in the trap; one uses a Monte Carlo Wave Function (MCWF) approach and the other integrates the Bloch equations to evolve the expectation value of the spin. These were first applied in modeling depolarization rate dependence on holding field strength. Calculations will be presented using the semiclassical approach and compared to results of the MCWF approach and empirical data. |
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HA.00064: Determination of the Neutron Capture Cross Section of 134Xe at En=4.2 and 5.5 MeV Andrew Lawrence Hall Neutrinoless double beta decay experiments using 136Xe contain a significant amount of 134Xe. Understanding backgrounds in double beta decay experiments is extremely important. The ultimate goal of this experiment is to determine the neutron capture cross section of 134Xe. This calculation will aid in correcting for neutron-induced background in measurements. After activating 134Xe in a neutron beam, γ rays from the resulting decay of 135Xe are measured over time. This decay allows us to determine how much 135Xe was produced, and calculate the neutron capture cross section of 134Xe. The immediate goals of data analysis were to calibrate detectors used, determine their efficiency, and calculate neutron capture cross section of 134Xe. |
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HA.00065: Measurement of Neutron Inelastic Scattering Cross Section on 76Ge at En = 4.5 MeV for Applications to 0νββ Decay and Dark Matter Studies Leonard D. Mostella III Neutrinoless double beta (0νββ) decay studies are both the best way to determine the Majorana nature of the neutrino and its effective mass. Many experiments searching for 0νββ decay, as well as other rare event physics such as dark matter interactions, use 76Ge as the detection medium (and also as the source in 0νββ searches; Q value = 2039 keV). Consequently, due to the rarity of these events (T0ν½ > 1024 years), these experiments require an ultra-low background environment in addition to highly precise background characterization. Some of the more problematic backgrounds are those from neutron interactions such as neutron capture (n,γ) and neutron inelastic scattering (n,n’γ) reactions. An experiment has been performed at the Triangle Universities Nuclear Laboratory (TUNL) to investigate the neutron inelastic scattering cross section on 76Ge at En = 4.5 MeV. The data from this experiment is currently being analyzed, and the materials to be presented here include experimental setup, analysis procedures and techniques, and present status.
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HA.00066: The Structure of 34Mg Nuclei Benjamin K Luna
In the chart of nuclides, there exists an area near the N=20 shell closure where the ground states of some isotopes exhibit characteristics of deformed nuclei with an intruder configuration rather than being spherical. This area is known as an “island of inversion”, and the deformed ground states that characterize it are caused by particle hole excitations over a reduced shell gap. This project is part of an ongoing investigation into the island of inversion using beta decay as a probe to study the low-energy structure. For this summer project, the beta-decay of 34Mg into 34Al was observed and the data from this decay was used to create a decay level scheme for 34Al. To collect the products of this decay, a beam of 34Mg was sent to a moving-tape collector system surrounded by plastic scintillators (SCEPTAR) and high-purity germanium detectors (GRIFFIN) at TRIUMF in Vancouver, BC. The data from this decay was collected into ROOT files, energy calibrated, corrected for gain differences and shifts, and sorted into a decay level scheme for 34Al. Future work on this project includes the use of angular correlations between gamma transitions to determine spins and parities of excited states of 34Al. |
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HA.00067: Level Structure and Spin Assignments in 70Ga M. J. Heeschen, R. A. Haring-Kaye, K. D. Jones, K. Q. Le, C. L. Tan, D. C. Venegas Vargas, J. Doring, B. L. Abromeit, R. Dungan, R. S. Lubna, S. L. Tabor, P.-L. Tai, Vandana Tripathi, J. M. VonMoss, S. I. Morrow Currently, little is known about high-spin states in odd-odd 70Ga. However, a 9+ state was identified at 2887 keV, which could be the start of a high-spin rotational band based on a proton and neutron occupation of the g9/2 orbital. The goal of this work was to search for evidence of this structure. The 70Ga nuclei were produced following the 62Ni(14C, αpn) reaction at 50 MeV performed at Florida State University. The γ decays were detected in coincidence with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. Spins were assigned from measured directional correlation of oriented nuclei (DCO) ratios and their comparison with theoretical values. A new high-spin band based on the 9+ state was observed and appears to show rotational character. The behavior of the moment-of-inertia of this band is similar to that of other odd-odd nuclei in this mass region, but the signature-splitting pattern indicates an irregular phase reversal at high spin. |
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HA.00068: The Search for πf7/2 Intruder States in 73As Amelia A Doetsch, Robert A Haring-Kaye, Kamali Jones, K.Q. Le, S. Gowen, J. Doring, Brittany L Abromeit, Rutger Dungan, Rebeka Sultana Lubna, Samuel L Tabor, Pei-Luan Tai, Vandana Tripathi, J. M. VonMoss, S.I. Morrow Proton occupation of the f7/2 orbital (the πf7/2 configuration) in the mass A ∼ 70 region is rare since it would require large prolate shape deformation (β2 ≥ 0.4). So far, there are only two known cases of such an occupation in this region (71As and 67Cu). The aim of this study was to search for evidence of πf7/2 states in 73As. High-spin states in 73As were populated using the 14C(62Ni, p2n) reaction at 50 MeV performed at Florida State University. A Compton-suppressed Ge detector array made up of three Clover detectors and seven single-crystal detectors was used to record γ−γ coincidences. Directional correlation of oriented nuclei ratios (RDCO) were used to assign spins. Coincidence data showed no evidence of an f7/2 band structure. Furthermore, a state at 577 keV that was previously thought to have a spin of 7/2 (and which could be the head of a πf7/2 band) was instead determined to have a spin of 5/2 based on RDCO measurements. These results suggest that there is no πf7/2 orbital occupation in 73As. |
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HA.00069: Confirmation of irregular signature splitting in 74As B. Ivanic, R. A. Haring-Kaye, K. D. Jones, K. Q. Le, S. Gowen, J. Doring, B. L. Abromeit, R. Dungan, R. S. Lubna, S. L. Tabor, P.-L. Tai, Vandana Tripathi, J. M. Vonmoss, S. I. Morrow Most odd-odd nuclei in the mass A ~ 70 region exhibit a consistent alternating pattern in the energy differences between adjacent states (signature splitting) in their strongest positive-parity bands. In odd-odd 74As, the pattern shows an irregular phase reversal at high spin, which has been attributed to the onset of an unpaired band crossing with an underlying triaxial deformation. However, this interpretation depends critically on the behavior of the signature-splitting pattern, which is based on uncertain spin assignments. The motivation for this study was to make firm spin assignments in the strongest positive-parity band of 74As. High-spin states in 74As were produced using the 14C(62Ni, pn) reaction with a beam energy of 50 MeV at Florida State University. γ-γ coincidences were measured using a Compton-suppressed Ge detector array comprised of three Clover detectors and seven single-crystal detectors. Measurements of directional correlation of oriented nuclei (DCO) ratios were used to confirm most of the spin assignments in the strongest positive-parity band, supporting the interpretations of previous work. |
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HA.00070: Measuring Low Energy Nuclear Cross Sections using ICF Katelyn Cook, Emma Bruce, Sarah Hull, Mark Yuly, Stephen J Padalino, Craig Sangster, Sean Regan Inertial confinement fusion is a tool that can be used to for fundamental nuclear science measurements. In the method under consideration, nuclear reaction products in the expanding atomic gas following the target implosion will be collected and trapped using a turbomolecular pump. The beta-decay of reaction products with half-lives ranging between 20 ms and 10 s will be measured in-situ using a phoswich detector system milliseconds after the implosion. Several previously unmeasured low-energy deuterium and tritium radiative capture and stripping cross sections could be measured using this technique. To study the feasibility, several small scale experiments are being carried out at Houghton College and SUNY Geneseo to simulate the rapid release of gas by the ICF target, its subsequent capture and decay counting. |
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HA.00071: A Statistical Method for Determining Stellar Reaction Cross Sections Keilah Davis, Richard Leigh Longland The 22Ne(p,γ)23Na reaction may have a significant effect on the surface abundance of sodium in asymptotic giant branch (AGB) stars. The rate of this reaction can be calculated using the angular momentum results from the 22Ne(3He,d)23Na cross section. We measured the 22Ne(3He,d)23Na cross section and used Bayesian statistics and Monte Carlo methods to determine uncertainties for angular momentum fitting parameters. We also used chi-squared tests and the overlap coefficient to quantify the impact of those uncertainties. We will present our findings and discuss their impact on the 22Ne(p,γ)23Na reaction rate. |
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HA.00072: Machine Learning Waveform Fitting to Improve Energy Resolution in P-Type Point Contact Germanium Detectors Zachary Hainsel, Matthew Green, Benjamin E Shanks The Majorana Demonstrator is an array of High-Purity Germanium (HPGe) detectors searching for neutrinoless double-beta (0νββ) decay in 76Ge. The Demonstrator combines low-noise electronics with the excellent intrinsic energy resolution of HPGe detectors to attain the best energy resolution of any 0νββ search, thus reducing the background rate in the 0νββ region-of-interest. Trapping of drifting charges in the bulk of the detectors can negatively impact the energy resolution and detector performance. The Majorana collaboration has developed a machine learning approach that can model and fit HPGe detector signals with sub-percent precision, and can be used to extract event information from a waveform. Once a number of parameters describing the detector and electronics response are determined, this waveform fitting technique can be used to infer the interaction locations for a particular event. Using the deposition origin, we can model the drift path of the charge-carriers. A charge trapping correction based on the carrier’s drift path length, which is in development, has the potential to further improve the Demonstrator's overall energy resolution. |
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HA.00073: New Level Structure of 162,164Gd Christian Ross Brown, Jonathan Mark Eldridge, Enhong Wang, Christopher J Zachary, Akunuri V Ramayya, Joseph H Hamilton, Brooks M Musangu, Thomas Henry Richards, Yixiao Luo, John Ramussen, Shengjiang Zhu, Gurgen M Ter-Akopian, Yuri Oganessian Levels in 162,164Gd were constructed via γ-γ-γ and γ-γ-γ-γ coincidence data from observations of 252Cf spontaneous fission. γ-rays from fission events of a 62 μCi 252Cf source were measured in the center of the Gammasphere detector array. This produced 5.7x1011 γ-γ-γ or higher coincidence events and 1.9x1011 γ-γ-γ-γ or higher coincidence events. This data set was analyzed to construct new energy level schemes for 162,164Gd. Levels and transitions previously identified in the ground state rotational bands have been confirmed. Additionally, several new transitions and levels are observed in both isotopes, including the establishment of a γ vibrational band from 2+ to 9+ for the first time, and the addition of a level in the yrast band of 162Gd. |
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HA.00074: Determining Yields of Fragment Pairs from Californium-252 SF Decays Thomas Henry Richards, Joseph H Hamilton, Brooks M Musangu, Enhong Wang, Jonathan Mark Eldridge, Christopher J Zachary, Akunuri V Ramayya, Christian Brown, Yixiao Luo, John Ramussen, Shengjiang Zhu, Gurgen M Ter-Akopian, Yuri Oganessian We analyzed data from the spontaneous fission of californium-252 (Cf-252) to determine yields for the fission partner element pairs tellurium(Z=52)/palladium(Z=46) and strontium(Z=38)/neodymium(Z=60). Previously, the case of barium(Z=56)/molybdenum(Z=42) was shown to have unusually high 8, 9, and 10 neutron emissions, (S.-C. Wu et al.) compared to other element partners seen in the spontaneous fission of Cf-252. With updated level schemes and a larger coincidence dataset, we tested the uniqueness of this case (A.H. Thibeault et al.) by analyzing the neutron channels of the two aforementioned element pairs. Via coincidence counting on γ-γ-γ gates, we measured ground state energy transitions of the studied isotopes to determine the relative yields of all visible isotope partner pairs. We placed the yields in a matrix that quantifies how often two specific isotopes of daughter elements appear in the spontaneous fission of Cf-252. We see that, in our studied elements, the higher neutron channel numbers have negligible yields, confirming the uniqueness of the Ba--Mo case, which may indicate a highly energetic, hyperdeformed Ba-144 nucleus at scission. |
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HA.00075: Investigation of neutron activation of 93Nb for a determination of the weak axial vector coupling constant from the 94Nb beta-decay spectral shape Alexander Arnold, Matthew Redshaw The effective value of the weak axial vector coupling constant gA in nuclear β-decay is of significant theoretical interest and is particularly important for calculations of nuclear matrix elements for neutrinoless double β-decay. Recent theoretical studies have shown that gA can be determined by comparing the shape of calculated and experimental β-decay spectra that, for certain nuclides such as 94Nb, are sensitive to gA. We are performing preliminary studies for a measurement of the 94Nb β-decay spectrum. This includes studying the production of 94Nb via the 93Nb(n,γ)94Nb reaction using an Am-Be neutron source. Using a Ge detector, we have studied the γ-ray spectra of activated 93Nb samples. Initial findings indicate that the 93Nb(n,2n)92Nb reaction dominates over 93Nb(n,γ)94Nb due to the small neutron capture cross-section of 93Nb. The decay of 182Ta was also observed, consistent with neutron activation of 181Ta impurities in our sample. Results for neutron flux calibration of our Am-Be source using the 92Nb and 181Ta data, and prospects for performing a measurement of the 94Nb β-decay spectral shape will be discussed. |
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HA.00076: A cylindrical Penning trap with rare-earth magnet for use as a low current ion source and mass spectrometry demonstrator apparatus Zachary Purcell, Ramesh Bhandari, Nadeesha D Gamage, Madhawa V Horana Gamage, Matthew Redshaw The Central Michigan University (CMU) High-Precision Penning trap mass spectrometer (CHIP-TRAP) is currently being developed for measurements with long-lived and stable isotopes. For this apparatus, an electron impact ion source consisting of a cylindrical Penning trap housed inside of a 0.5 T NdFeB ring magnet has been built. This source will allow ions to be produced and stored in a small volume and released as a bunch for low current pulsed beams. As an extension of this work, we are investigating use of this trap as a Fourier Transform Mass Spectrometer (FTMS) demonstrator to be used, for example, in advanced undergraduate experimental physics courses. The cylindrical ring electrode has been quartered to enable the cyclotron motion of trapped ions to be driven by applying RF between two opposite segments, while the remaining two segments are used for detection of image currents induced in the electrodes by the ions. The image current signal will be amplified, digitized, and analyzed using FFT techniques. In this poster, I will discuss the design, construction, and initial testing of both the electron impact ion source and FTMS demonstrator set-ups. |
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HA.00077: P-type Point Contact (PPC) High-Purity Germanium Detector Performance at Low Temperatures Sabrina Ying Cheng Observing rare events such as neutrinoless double beta decay (0νββ) requires good energy resolution and low background rates. The GERDA experiment has met these requirements by operating PPC detectors in a liquid argon active veto. However, 39Ar β decays create high backgrounds at low energy. Instead, liquid neon has been proposed, but PPC detectors have not been tested at such low temperatures where charge trapping may degrade energy resolution. At these temperatures, position-dependent trapping increases, reducing the total charge collected from events. A single-detector cryostat was cooled to liquid neon temperature and energy resolution was analyzed at various temperatures after correcting for charge trapping via the technique used in the MAJORANA DEMONSTRATOR. If the charge trapping effect can be appropriately corrected for, good energy resolution can be recovered even at low temperatures. This would allow LEGEND, a next-generation 0νββ search, to employ liquid neon and pursue an additional low-energy physics program, including searches for WIMP scattering and solar axions. |
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HA.00078: Purification of Germanium Crystals by Zone Refining Alexandra Kirkvold The nature of dark matter (DM) and key properties of neutrinos are two of the most important questions in particle physics. PIRE-GErmanium Materials And Detectors Advancement Research Consortium (PIRE-GEMADARC) is a global partnership created to accelerate the germanium (Ge) material platform used to research these questions and educate the next generation of scientists. In developing high-purity Ge (HPGe) detectors, zone refining is one of the most important techniques. Raw Ge contains many impurities, like Al, B, and P. Our goal is to decrease the distribution density of impurities along a Ge ingot. Zone refining is the simple process of a heating induction coil passing over the ingot and melting a strip that moves as the coil continues its pass. Impurities move within the molten zone; so once this process is done several times, most impurities have been shifted to either end of the ingot and the rest of the rod is purified Ge. The effective isolation of impurities is dependent on many parameters: the travel speed, ratio of ingot length to molten zone width, and number of passes. Refined ingots are grown into crystals that are manufactured into HPGe detectors used in the search for DM and in neutrinoless double beta decay experiments. |
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HA.00079: Electrical Conductivity of High-Purity Germanium Crystals at Low Temperature Kyler Kooi, Gang Yang, Guojian Wang, Hao Mei, Yangyang Li, Dongming Mei The temperature dependence of electrical conductivity of single crystalline and polycrystalline high purity germanium (HPGe) samples has been investigated in the temperature range from 7-100K. The conductivity versus inverse of temperature curves for the two sample types have distinct behaviors at different temperature regions and turning points (freeze-out temperatures). Calculations show that the net carrier concentration increases with increasing temperature due to thermal excitation, but it reaches saturation around 40K for the single crystal samples and 70K for the polycrystalline samples. These differences between the single crystal samples and the polycrystalline samples are attributed to trapping and scattering effects of the grain boundaries on the charge carriers. The relevant physical models have been proposed to explain these differences in the conduction behaviors between two kinds of samples. Understanding these properties is important for experiments using HPGe to detect dark matter or neutrinoless double beta decay. |
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HA.00080: Applications of Digital Pulse Acquisition Systems and Software Defined Electronics in Advanced Teaching Labs Nathaniel Damron, Frederick D Becchetti, Ramon O Torres-Isea The CAEN DT5790N is a digital acquisition system which houses two high voltage supplies and two highspeed (12 bits, 250MHz) waveform digitizers. These in tandem with the use of post processing software combine to produce a Software Defined Electronic (SDE) system that can be used in several advanced teaching lab experiments. An FPGA and built-in software can be used to display the pulse waveform and produce a time-stamped output (4 ns intervals) in a text list for post processing, e.g. via MATLAB, Python, LabVIEW, ROOT, BASIC,etc. The SDE can then be reconfigured and used to run many nuclear and other experiments in an advances teaching lab course. This serves to expose students to modern state-of-the-art data acquisition technology. Experiments such as Fission Neutron Time-of-Flight, Compton Scattering, Co-60 Gamma Coincidence and Na-22 Gamma-Gamma Annihilation are well suited for SDE. The SDE system also provides a very adaptive and cost-effective substitute for NIM or CAMAC electronics as SDE can be easily set up with only a single digitizer box and computer for many different experiments. Typical data using SDE we have developed for several advanced teaching lab experiments will be shown. |
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HA.00081: Projectile-like fragment production studies: the role of magnetic rigidity Jonathan Hu, the MoNA Collaboration At rare isotope beam facilities around the world, projectile fragmentation is used to create exotic beams. A primary beam strikes a production target, creating projectile-like fragments which are precursors to stable secondary beams used for experimentation. Due to the short-lived nature of these projectile-like fragments, it is impossible to directly observe them. The MoNA Collaboration designed and performed an experiment at the NSCL to study projectile-like fragment production. A 32Mg 86 MeV/u secondary beam struck a reaction target of 9Be, creating charged final fragments of sodium, neon and fluorine along with correlated neutrons. After the reaction target, charged fragments are bent by a Sweeper magnet into an ensemble of charged particle detectors, while neutrons continue into the Modular Neutron Array. The detection of charged final fragments is predicated on the magnetic acceptance range of the Sweeper magnet, which was varied to increase the number of observed isotopes. Analysis of neutron multiplicities in relation to fragment acceptance is necessary to accurately analyze these projectile-like fragments. Preliminary results of this study will be presented. |
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HA.00082: Projectile-like Fragment production studies using coincident neutrons Edith Tea, the MoNA Collaboration Intermediate and relativistic heavy ion beam facilities, like eventually the Facility for Rare Isotope Beams (FRIB), produce secondary beams for experiments through the creation of Projectile-like Fragments (PLFs). The short-lived and excited PLFs de-excite into radioactive isotopes through gamma and neutron emission. Production cross sections and momentum distributions give information about PLFs, but the complete fragmentation process is still unclear. The present work aims to understand the mechanism that occurs between beam and target nuclei by studying the multiplicity and kinetic energy distribution of neutrons emitted in coincidence with charged fragments. The MoNA Collaboration used the Modular Neutron Array (MoNA) to identify reaction produced neutrons at the National Superconducting Cyclotron Laboratory with an 86 MeV/u beam of 32Mg incident on a 9Be target. The Sweeper magnet bends the charged fragments that were then detected by a suite of charged particle detectors. Preliminary results of the neutron multiplicities and kinetic energy distributions analyzed in coincidence with the charged fragments will be presented. |
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HA.00083: Performance Studies of the Focal Plane System for the SEparator for CApture Reactions (SECAR) Hannah Nelson, J C Blackmon, C M Deibel, E Good, A A Hood, K Joerres, T J Ruland, A M Garrity The SEparator for CApture Reactions (SECAR) will be used to measure fusion reactions that are important in stellar explosions using beams of radioactive nuclei at the Facility for Rare Isotope Beams. We will describe performance measurements of the full focal plane system tested using alpha sources at Louisiana State University. The focal plane detector system utilizes three different types of detectors to identify fusion products. Two micro-channel plate (MCP) detectors are used together to measure the position and time of flight of particles to determine velocity. A silicon-strip detector or a gas ionization chamber is used as the stopping detector, measuring the energy, position, and atomic number through ΔE-E relative energy loss. Using the two MCP detectors and the silicon detector, we demonstrate position resolution of about 1 mm and a timing resolution of better than 1.1 ns. |
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HA.00084: Van de Graaff Voltage Regulation via PID Control Ryan Gonzalez Efficient operation of the Gettysburg College 250 keV Van de Graaff proton accelerator depends upon steady dome voltages to maintain beam at desirable energies (50 - 200 keV); all current and future research necessitates reliable beam. Since our proton beam runs through an analyzing magnet, voltage fluctuations impact available beam on target. To compensate a novel Arduino control system utilizing dome and slit feedback signals has been implemented, complete with operator and PID controls as well as live visual feedback on a graphical user interface. |
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HA.00085: SiPM Testing and Sorting Simulation for the sPHENIX Collaboration Shannon Dancler, Nathan C Grau The sPHENIX collaboration studies heavy ion collisions in an effort to better understand the strong nuclear force. The collaboration has proposed a new detector to be built at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The electromagnetic and hadronic calorimeters will use approximately 100,000 silicon photomultipliers (SiPMs) to detect light from showers produced in the calorimeters by particles produced by the collisions. The SiPMs will be supplied by Hamamatsu, model S12572-015P. There will be four SiPMs per calorimeter tower, all operated at the same voltage. The SiPMs need to be sorted so each calorimeter tower has balanced gain. One of the objectives of my research was to test the gain and operating voltage of an SiPM by measuring single photoelectron peaks shift with bias voltage. The second objective of my research was to develop a method to sort the tested SiPMs with similar gain into groups of four. In this poster I will give details of the test stand, show gain measurements, and the results of the simulation used to develop the sorting method. |
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HA.00086: Ionization Chamber Development for the Detection of Tritium Katherine Parham, Collin R Malone, Calvin R Howell Three nucleon interactions (3NI) are important to the understanding of nuclear structure. Current models require 3NI to accurately fit reported data. The 3NI can be further understood by measuring the neutron-neutron scattering length through the photodisintegration of tritium. The tritium target that will be used in this experiment must be safely transported between buildings at the Triangle Universities Nuclear Laboratory. Because tritium is a radioactive material and highly reactive, precautions must be taken during transportation. Four ionization chambers were built in order to monitor the intermediate containment chamber for tritium leaks. Two ionization chambers are open in order to monitor for tritium while the remaining two chambers are sealed for background subtraction. All ionization chambers will operate in air and will be battery powered for mobility. The electrons emitted through tritium decay only travel a few millimeters in air, so tritium gas diffusion will be essential for detection. 90Sr and 241Am were used to test the ionization chambers. When exposed to the 241Am source, the open detectors displayed a significant gain similar to what is expected should the tritium target leak. |
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HA.00087: Background Measurement of Gamma Rays, Muons, and Neutrons at LENA Clay Wegner The Laboratory for Experimental Nuclear Astrophysics (LENA) will be replacing its existing 1-MeV JN accelerator with a 2-MeV singletron whose size would be better accomodated by switching the location of the target from the east end of the lab to the west end. However, the amount of background radiation may be different at opposite ends of the lab due to the construction of the building. To determine the feasibility of relocating the target, the flux of gamma rays, muons, and neutrons were measured using a HPGe detector, a BC-408 scintillation detector, a sodium-iodide scintillation detector, and a model IV inventory sample counter (INVS) neutron detector. Background values at the current location were compared with those at the west end of the lab. Additionally, a GEANT4 simulation of the INVS counter was used to derive a cosmic ray-induced neutron flux from experimental data. Measurements indicate that the muon and neutron backgrounds at the current target location are lower than at the west end, but that the background from gamma rays is higher. Therefore, the target in LENA should remain in its current location, where the muon and neutron backgrounds are lower. |
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HA.00088: Fused Silica Raman Spectroscopy for the ATLAS Zero Degree Calorimeter Joseph Bryant The Nuclear Physics Laboratory (NPL) at the University of Illinois collaborates on the development of an improved Zero Degree Calorimeter (ZDC) to replace the current ZDC in the ATLAS experiment at the Large Hadron Collider (LHC). A prototype detector is presently designed for test beam studies at the CERN SPS in November 2018. The prototype is a tungsten-quartz sampling calorimeter that consists of two modules and contains a reaction-plane detector (RPD). Each module is made of 11 alternating layers of tungsten and 12 layers of fused silica fibers. The charged shower particles produced by an incident neutron emit Cherenkov light in the fused silica fibers. The Cherenkov light will be detected by photomultiplier tubes (PMTs). The high radiation that the fused silica rods experience due to their presence in the beamline causes different types of changes to the structure of the silica. The purity of the fused silica strongly impacts the defects that form within the rod. Raman spectroscopy is used as a method to study the specific defects present in the irradiated fused silica rods. The results of Raman spectroscopy measurements will be presented. |
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HA.00089: Profiling Quartz Activation in ATLAS ZDC BRAN Rods Thomas Krug The Nuclear Physics Group at the University of Illinois collaborates on the development of a new Zero Degree Calorimeter (ZDC) for the ATLAS experiment. The upgraded ZDC is intended to withstand the harsh radiation environment expected from the high luminosity LHC. For the past two years, the BRAN luminosity group at the LHC has irradiated highly pure fused silica rods at the ZDC’s shower max. These samples were then provided to the University of Illinois for detailed study of the impact of radiation dosage on the rods' chemical and optical properties. The total dosage received as well as particle species and spectrum have been estimated from simulation and nearby radiation monitors. To verify this, we measured the 7-Be and 22-Na activation along the length of the fused silica rods. This information will then be used along with the cross sections for isotopic production to extrapolate total dosage. This poster will present the position dependent profiles of 7-Be and 22-Na concentration along the length of the rods. These concentrations have been determined from the gamma decay spectra observed with a high-purity germanium detector. |
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HA.00090: Design and Drafting of Prototype Modules for the ATLAS ZDC Tiansu Zhang The Nuclear Physics Group at the University of Illinois is contributing to upgrade efforts of the ATLAS Zero Degree Calorimeter (ZDC). As part of this effort, two prototype modules along with a single layered reaction plane detector (RPD) are being built for a November beamtest. Improvements have been made to the mechanical design, as well as to the radiation hardness of the detector. Each module consists of 11 alternating layers of tungsten and 12 layers of fused silica fibers. Fused silica with high purity is used to increase the radiation hardness of the detector. In one of the two modules, the tungsten plates are oriented at the Cherenkov angle for better light collection efficiency. In the second module, the plates are oriented vertically. The difference in light yield and timing resolution will be studied for these two configurations. The RPD is also a new addition to the ATLAS ZDC and provides an additional layer of transverse segmentation. Details on the design and construction of these prototype modules will be presented. |
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HA.00091: Simulation of Light Collection for nEDM Experiment Minyang Tian The search for the neutron EDM (electric dipole moment) plays an important role in nuclear and particle physics and since it will give direct evidence for the violation of time-reversal symmetry and for physics beyond the Standard Model. The goal of the nEDM experiment at Oakridge National Lab is to further improve the experimental sensitivity by another factor of 100 compared to the current experimental limit. My project is closely related to the signal (scintillation light) generated from the capture reaction of spin-dependent neutron and Helium-3. In this project, we try to improve the design for higher light detection efficiency. For this purpose, we perform a full-scale simulation of the measurement cell for the upcoming nEDM experiment using Geant4, in the order to optimize light output of the cell. In particular, I use experimental data from test setups to check the properties of various components in the simulation, such as light sources, the reflector tent, wavelength shifting fibers, wavelength shifting TPB and acrylic. Afterwards, the experimental data are used to successfully validate full scale simulation of the test setups. We are in the process of building a realistic simulation for the nEDM light collection cell for optimization studies. |
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HA.00092: Title: Simulations of a Modular Cosmic Ray Test StandAuthor: Kolby Kiesling for the ACU Nuclear Physics Research Group Kolby James Kiesling The modular cosmic ray test stand is used to determine the efficiencies of prototype detectors through tracking cosmic ray muons. The purpose of the cosmic stand is to test prototype detectors at ACU for use either locally or on experiments at national laboratories. The cosmic ray stand is designed as four segmented plastic scintillators with photomultiplier tubes (PMTs) located on both ends of each scintillator for the upper and lower planes. The data acquisition system (DAQ) records the timing differences of waveforms to generate 2D cosmic ray positions at each plane that is used to reconstruct 3D cosmic ray flight paths. The simulation, written in parallel to construction of the stand, produces expected cosmic ray rates of the stand. A key feature of the simulation is its ability to simulate optimal separation distances and angle orientations of the stand when testing a prototype detector. The data from the completed test stand agrees with expected cosmic rates from simulations. This presentation will describe the design, construction and simulation of the stand, as well as cosmic ray rate comparisons between data and simulations. |
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HA.00093: Design and Construction of a Molten Salt Test Loop for Advanced Reactor Development Michael Bryan Ranger The Nuclear Energy eXperimental Testing (NEXT) collaboration is creating the solutions to solve the world’s energy and water crises through the advancement of molten salt reactors. The Molten Salt Test Loop (MSTL) was constructed for the testing of advanced instrumentation and to collect data about the physical and fluidic properties of molten salt. The MSTL is made to withstand 900°C, hold 7 gallons of liquid in its reservoir, produce both laminar and turbulent flow, and test experimental instrumentation. For safety and efficiency purposes, an insulation system was fitted around the loop and is monitored by thermocouples run on a MIDAS based Data Acquisition System (DAQ). The MSTL has several ancillary systems including trace heating, gas blanket system, insulation, evacuation chamber, and flow control. These ancillary systems allow for precise control over the loop. The DAQ system both operates and stores data related to the ancillary systems. The MSTL initially ran water to characterize the pump and loop and was converted to run Dynalene, a low melting-temperature nitrate salt. Moving on, high melting-temperature fluoride salts like FLiNaK will be run. This presentation will summarize the design, status, and the ancillary systems of the MSTL. |
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HA.00094: Using Machine Learning to Differentiate Signals from Background Events for SeaQuest John Marsden SeaQuest/E906 at Fermi National Accelerator Laboratory studies the anti-quark structure of the nucleon. A 120 GeV proton beam was collided with a series of fixed targets and created dimuons through the Drell-Yan process. The detectors observing this also observed many background muons from unrelated particle decays. We are using machine learning techniques to better separate such background events from signal events with the TMVA (Toolkit for Multivariate Analysis) package included in ROOT which contains machine learning classifiers such as Neural Networks, Boosted Decision Trees, and more. The signal samples are dimuons generated by a Monte Carlo simulation while the background samples are from real data collected via a single muon trigger. We are also exploring what kinematic variables create the most efficient markers for classification. This presentation will cover the selection of training and testing data, classifiers used, input features, and parameters that optimize the dimuon event selection for physics understanding. |
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HA.00095: Experiment 1039 at Fermi National Accelerator Laboratory Roy Salinas Experiment 1039 at Fermi National Accelerator Laboratory is poised to better understand the contribution of the sea quarks to the nucleon spin and is the successor to Experiment 906/SeaQuest. E1039 will utilize a 120 GeV proton beam, the mass spectrometer previously used in SeaQuest, and a transversely polarized target to have spin-dependent collisions. It has been known that the valence quarks contribute ~30% to the proton spin while the contribution of the gluons is still being studied. The main focus of E1039 will be to measure the Sivers function, which is a correlation between transverse spin of the sea quarks and nucleon spin, through the Drell-Yan process. Measurement of a non-zero quark Sivers function implies a dependence on quark orbital angular momentum for nucleon spin. A direct measurement of the Sivers function will provide further the efforts in solving the proton spin crisis by determining if there is a non-zero contribution of the sea quarks to the nucleon spin. |
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HA.00096: Title: Remodeling of an E906 spectrometer to be used for E1039.Author: Yves Ngenzi, Abilene Christian University for E1039 Collaboration.This Research was supported by US DOE MNP Grant DE-FG02-03ER41243. Yves Ngenzi Abstract: For decades, the spin of the proton has presented a problem. This launched studies of sea-quark and gluon contributions. Fermilab E1039 is pursuing the sea-quark contribution. It will focus on Sivers function which represents the correlation of the transverse momentum of an unpolarized proton with the spin of a transversely polarized nucleon. We will use the high luminosity 120 MeV proton beam and polarized ammonia targets, NH3 and ND3, to measure the Sivers function for u bar and d bar sea quarks in the nucleon for Bjorken x in the range 0.1 < x < 0.5, using the Drell-Yan process. This will be the first determination of the Sivers function for sea quarks in this x range. The E1039 spectrometer and planned improvements to do this sensitive measurement will be presented |
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HA.00097: Recent Upgrades to the Time Projection Chamber for the NIFFTE Collaboration Jared Thomas Barker The NIFFTE (Neutron Induced Fission Fragment Tracking Experiment) collaboration aims to create a more accurate measurement of the cross section as a function of incident neutron energy. In order to accomplish this, the collaboration designed and installed a fission Time Projection Chamber (TPC) at Los Alamos National Lab. A neutron beam is directed at a thin fissile target, potentially causing a fission event, which can be tracked by the TPC. Recent upgrades to the TPC have allowed it to perform better and improve ease of operation. This includes implementing a high-temperature cutoff switch and incorporating a PID fan for stable temperature controls. Monitoring the TPC and analyzing the data can also be streamlined by implementing automatic comparisons of histograms via the Kolmogorov test. This can potentially act as an aid for shifters by notifying them of inconsistencies immediately or reporting differences that may be too subtle to be noticed visually. This presentation will give an overview of the NIFFTE collaboration’s goals, recent upgrades to the TPC, and future applications of the project. |
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HA.00098: Computational study of radioactive cesium capture in copper hexacyanoferrate structures for nuclear waste applications Spencer Sunwoo Hong, Simerjeet Gill, Mehmet Topsakal Radioactive cesium is one of the most common and problematic products of nuclear fission and energy production. Currently, there is no permanent solution to rid nuclear waste of radioactive cesium. Copper hexacyanoferrate compounds, known as Prussian blue analogues (PBA), have shown early promise in capturing cesium cations through a sorption mechanism. Using the institutional cluster at Brookhaven National Laboratory (BNL), we utilize density functional theory calculations to characterize the structure of PBAs as well as its changes during the cesium exchange. Computational models allow us to refine structural details that may be difficult to explore experimentally. We investigate the PBA structure before and after cesium exchange to provide insights into the sorption mechanism to complement experimental studies using X-ray diffraction methods. Based on our results, we show that the lattice structure expands when the potassium is exchanged with cesium due to the larger ionic radius of cesium. Furthermore, the modeling studies support the structural assumption that cesium prefers to occupy the center of the cavity, the Wyckoff 8c site. |
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HA.00099: Gluon Contribution to Proton Spin and the Connection to Forward Calorimetry at STAR Miya Bailey The proton has an intrinsic spin derived from its quark and gluon components. While the quark spin contribution to the spin of the proton is relatively well known, the gluon spin contribution is comparatively poorly constrained. The STAR (Solenoidal Tracker at RHIC) collaboration is working to constrain this value by analyzing spin-polarized proton collisions. One analysis uses neutral pions (𝛑0s) detected by the Endcap Electromagnetic Calorimeter (1<η<2). We measure the number of 𝛑0s from same and opposite helicity collisions and calculate the production asymmetry, which is related to the gluon contribution. We are beginning to analyze the dataset from 2013, which is about three times the size of the 2012 dataset, whose analysis is more mature. Currently at Brookhaven National Laboratory, the Forward Meson Spectrometer (FMS, 2.5<η<4.0), which was used for the measurement of forward 𝛑0s, is being decommissioned for the installation of a forward upgrade (2.5<η<4.0) which in addition to tracking will feature electromagnetic and hadronic calorimetry as part of a Forward Calorimeter System (FCS). I will discuss the Run 13 𝛑0 asymmetry analysis, FMS decommissioning, and proposed upgrade. |
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HA.00100: A Jet Shape Analysis with Au+Au Collisions Collected by STAR Marcelo Almora Rios, Sevil Salur, Joel Mazer Quark-gluon plasma (QGP) is a unique state of matter that can be produced in relativistic heavy ion collisions. One way to study the properties of the QGP is by observing its “quenching” effects on the products of hard-scattered particles, or jets. Jets are studied in Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV using STAR experiment data taken at the Relativistic Heavy Ion Collider (RHIC). The jet shape observable, $\rho$, is defined as the fraction of the total transverse momenta from charged particle constituents of a jet to the transverse momenta of the jet itself [1]. In this poster, we will be presenting a preliminary analysis of jet shapes for jets reconstructed with the anti-kT sequential recombination algorithm in heavy ion collisions [2]. [1] Chatrchyan, Serguei et al., Modification of jet shapes in PbPb collisions at $\sqrt {s_{NN}} = 2.76$ TeV, Phys.Lett. B730 (2014) 243-263 [2] Cacciari, Matteo and Salam, Gavin P. and Soyez, Gregory, FastJet User Manual, CERN-PH-TH-2011-297 |
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HA.00101: Charge-Dependent Mixed-Harmonic Correlations Relative to the Reaction Plane in Au+Au Collisions at 200 GeV at RHIC/STAR YOUN JUN CHO In the chiral magnetic effect (CME) [1], an electric current is induced in the presence of a strong magnetic field and a chirality imbalance in the medium created in high-energy nuclear collisions. One corresponding observable for the charge separation across the reaction plane ($\psi$) is the charge dependent two-particle azimuthal correlator, $\gamma_{112}= <cos(\phi_1 + \phi_2 - 2\psi)>$. However, the $\gamma_{112}$ contains both the CME signal and the flow background, complicating the interpretation of the data. In this poster, we investigate the background mechanism with a modified mixed-harmonic correlator, $\gamma_{132} = <cos(\phi_1 - 3\phi_2 + 2\psi)>$. The $\gamma_{132}$ only contains the background, and reflects the role played by the collective flow in the original $\gamma_{112}$ correlator. We will present the STAR data of $\gamma_{132}$ as a function of centrality measured in Au+Au collisions at 200 GeV. The results will be compared with model calculations. The physics implications will be discussed. [1]D. Kharzeev, Phys. Lett. B 633 (2006) 260. |
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HA.00102: Novel, Portable and Low-cost Cosmic Ray Muon Telescope Jessica Eskew, Sawaiz Syed, Xiaochun He Cosmic ray (CR) particles (mainly high energy proton particles) of galactic and solar origins are continually bombarding the earth. These CR particles produce extensive CR showers starting around 15 km altitude. The dominate CR particles to reach the earth surface being muons (about 80%). Many useful applications of CR muons include muon tomography and atmospheric weather study. The Nuclear Physics Group (NPG) at Georgia State University (GSU) has been developing low-cost and portable muon detectors with interests of worldwide installation for measuring CR muon flux variations to advance the technology of monitoring dynamical changes of the earth/space weather. The muon telescope detector consists of three layers of plastic scintillation mounted on an aluminum extrusion frame. Collected scintillation light is sent to a multi-pixel photon counter (MPPC). Data acquisition is performed with a custom-made Raspberry Pi Hat. A detector prototype was tested in June of 2018 behind beam shielding blocks at the Fermilab Test Beam Facility with a 120 GeV/c proton beam. My work mainly entails building components, soldering circuit boards, assembly, programming readout electronics and data analysis. This talk will highlight the detector's design features and present my data analyses results. |
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HA.00103: Determining Light Decay Curves in Plastic Scintillators using Cosmic Ray Muons Stephen J Padalino, Sarah Mandanas, Praveen Wakwella, Hannah McClow, Emily Vanderbilt, Kazuyoshi Sampson, Sean Regan, Craig Sangster Plastic scintillators are used in HEDP and ICF research to measure neutron energies using a time of flight method. The energy resolution and sensitivity of an nToF system has a direct correlation to the scintillation decay time of the plastic. To decrease the decay time, xylene scintillators are quenched with oxygen and consequentially become less efficient at producing light. As time passes, the scintillator becomes oxygen deficient which increases light production and the decay time. Mono-energetic calibration neutrons used to monitor these increases are unavailable at most HEDP and ICF facilities. As a result, it is difficult to determine if oxygen concentration has decreased within these systems. Here, a possible method of calibrating xylene detectors in situ is presented. If the detectors response to cosmic ray muons is known, it can be used to determine the scintillation decay curve produced by a mono energetic neutron. As a result, the need for the remote accelerator based calibration of the xylene detectors is eliminated. |
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HA.00104: Optimization Methods for Track Fitting in the Active-Target Time Projection Chamber Ruiming Christina Chen, Michelle Kuchera, Daniel Bazin Local and global optimization methods were evaluated for fitting spiral tracks in the Active-Target Time Projection Chamber (AT-TPC) at the National Superconducting Cyclotron Laboratory at Michigan State University. The AT-TPC is a gas-filled chamber that acts as both the target and the detector for studying nuclear reactions. Using this, we can reconstruct three-dimensional spatial tracks of the reaction products. Track-fitting methods were tested on data from the $^{46}$Ar(p, p) and $^{40}$Ar(p, p) experiments that ran in 2015. We aim to improve on the current fitting method in the analysis software, the naive Monte Carlo algorithm. Various optimization methods were tested, with notable success using global optimization methods, specifically, differential evolution and basin hopping. Local optimization methods were tested in the basin hopping algorithm in order to examine the performance impact. Results will be presented that compare the accuracy, robustness to noise, and time efficiency of each method. |
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HA.00105: Machine Learning and Track Reconstruction for the MOLLER Experiment Mary Robinson The purpose of this project was to develop a neural network to reconstruct particle trajectories in the MOLLER experiment. The MOLLER experiment is a collaboration at Jefferson Lab which plans on testing the Standard Model by measuring the parity-violating asymmetry in Moller scattering. If the measurement disagrees with the theoretical value for the asymmetry, then it will provide evidence for physics beyond the Standard Model, and if it agrees, it will restrict many beyond-the-Standard-Model theories being developed. A necessary aspect of this experiment will be the reconstruction of particle trajectories. Neural networks are efficient pattern recognition tools and are equipped to handle large datasets, so they are a potential solution to this issue. Using data generated by the Geant 4 simulation for MOLLER, I trained a recurrent neural network which connects signals in a series of tracking detectors to signals in the main detector located downstream. It does so by predicting the position of a particle hit in the main detector from that particle's hit positions in each of the tracking planes. The network predicts the main detector hit positions with better than 1% error. |
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HA.00106: Construction of a Wire Chamber for Reactor Neutrino Studies Hannah Choe Hasan, Connor Awe Neutrino interactions can be used as a probe for exploring physics beyond the Standard Model. However, the rarity of neutrino interactions and presence of high backgrounds make detection difficult. We wish to construct a time projection chamber (TPC) capable of reconstructing the kinematics of an inverse beta decay event. The TPC will detect the products of inverse beta decay using isobutane as the target material. As isobutane is not a well-characterized gas, we have constructed a wire chamber to study quenching factors in isobutane. We first study the wire chamber’s response for known spectra, obtaining a muon spectrum using P-10 gas as a target. In the future, we will use the wire chamber to characterize isobutane for use in the TPC. Additionally, we have created a GEANT4 simulation package for a commercially bought wire chamber that is filled with an unknown target gas, and seek to calibrate the chamber. |
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HA.00107: Unfolding and Analysis for the Helium and Lead Observatory John Franklin Crenshaw, Kate Scholberg The Helium and Lead Observatory (HALO) at SNOLAB is a supernova neutrino detector and a member of the Supernova Early Warning System (SNEWS). The detector consists of 128 3He counters embedded in a 79-ton lead matrix. Depending on energy, neutrino interactions with lead may generate single (1n) or double (2n) neutron events. The relative rates of 1n and 2n events are sensitive to supernova neutrino spectra. It is therefore important to evaluate HALO’s detection efficiency and to develop a method for reconstructing true 1n and 2n numbers from detected events. The matrix-inversion unfolding produces unphysical results and large uncertainties. A Bayesian algorithm removes unphysical results and tuning the prior to the expected range of supernova and neutrino oscillation parameters reduces uncertainty. A figure of merit is developed that evaluates the effectiveness of the unfolding over a range of supernova distances. HALO-1kT, the proposed 1 kiloton upgrade at LNGS, is also evaluated. |
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HA.00108: Event Generator for Neutrinos on Deuterons Jessica Koros, Kate Scholberg COHERENT is a collaboration studying coherent elastic neutrino-nucleus scattering (CEvNS), a process with a well predicted but very small cross section. Several detectors are operated at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory to study CEvNS. Currently there is ~10% uncertainty in neutrino flux at SNS. This uncertainty can be reduced with the addition of a heavy water detector which will measure neutrino flux. Simulations will be done to study the feasibility and efficacy of this detector. The purpose of this project is to create an event generator for these simulations. This involved constructing 2D histograms from tables of double differential cross section calculations for the reaction. These cross sections have been weighted by the SNS flux, allowing for the random selection of events weighted by both the flux distribution and cross section information. This gives a sample of randomly generated electron events that are a realistic representation of reactions at SNS for input into a Monte Carlo simulation. Additionally, the code written to create these distributions will be made available for application to similar projects. |
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HA.00109: Tracking Crystal-Based Sources of CUORE Background Byron Daniel The Cryogenic Underground Observatory for Rare Events (CUORE) contains a bolometer-based detector with Te02 crystals that is used to search for neutrinoless double-beta decay in the isotope 130Te. Searching for rare events such as neutrinoless double-beta decay requires a deep understanding of backgrounds. In particular, this project sought to identify crystal-based backgrounds by looking for correlations between the activities of certain isotopes and crystal parameters (e.g. when the crystal was created). This identification would allow the CUORE collaboration to be more confident about its understanding of the background spectrum. In this presentation, I will show the results from studies of the activities of multiple sources on the CUORE crystals in order to identify and track crystal-based contaminations. |
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HA.00110: Experimental Apparatus and Design for Parity-Odd Asymmetry Measurement in 139La Clayton James Auton The NOPTREX collaboration plans to conduct a sensitive search for time reversal violation in polarized neutron transmission through polarized 139La by taking advantage of the very large amplification of symmetry-violating effects already measured in the 0.734-eV p-wave resonance of 139La. As a step toward this experiment we are remeasuring parity violation in n + 139La on this resonance. We use two unpolarized 139La targets with a neutron spin flipper in-between to do this. The first 139La target polarizes the neutron beam and the parity-odd transmission asymmetry is measured by transmission through the second 139La target. We aim for 1% precision on the ~10% P-odd asymmetry at the resonance peak. I will describe the major components of the apparatus that I designed and constructed: the 139La cryostats and thermometry; a support structure for the cryostats, neutron spin flipper, neutron beam monitor, and beam collimators; and the shielding enclosure for the 6Li current-mode neutron transmission detector. |
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HA.00111: An Analysis of Multiple Muon Scattering in NOνA Data and Simulation Emily Grace Lynn The NuMI Oscillation νe Appearance Experiment (NOνA) is a long-baseline neutrino beam experiment based in Fermilab. Event reconstruction, by which the hits in the detectors are used to determine individual tracks and estimated kinematic information, makes particle identification and analysis in this and similar experiments possible. This research focused on accessing the accuracy of the model used to simulate multiple muon scattering, as well as determining the effectiveness of the reconstruction fitting algorithm used to track muon scattering. Data and simulation were compared using an expected RMS scattering angle derived from roughly common attributes of the real and simulated models. By comparing actual angles to expected RMS angles, we determined that there is good agreement between the data and the simulation. However, we have discovered the presence of errors and discrepancies within the tracking algorithm itself. These results have provided additional validation for the use of simulation in testing, as well as laid the foundation for further study into the improvement of algorithmic tracking of scattering particles. |
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HA.00112: Making Nuclear Sandwiches using BCC Crystal Lattices Terance Schuh, Zack Vacanti, Charles Horowitz Neutron star crust is made up of a variety of sub-layers all with different compositions. Although crust models using only a uniform, continuous single bcc crystal lattice distribution benefit from simplicity and symmetry, models involving multiple crystal domains are more accurate in terms of the reality of the situation. With elements like transport properties in mind, using molecular dynamics simulations we were able to develop a code that produces this nuclear sandwich model as it shall be referred to in this work. This nuclear sandwich model, comprised of a two crystal domain structure, is more representative of neutron star crust than the single crystal domain models. We then simulated the model's implications for when crystal structures at different angles relative to each other meet at this new interface. Results from running these simulations with only protons and no nuclear forces show that our nuclear sandwich remains stable and can now be further tested to include parameters such as varying densities, temperatures, and magnetic fields. |
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HA.00113: Particle Exchange Models in Three Body Systems Kevin Saldana The phenomenological description of three body resonances is of considerable interest in hadron spectroscopy. States such as the X(3872) have been discovered to decay near thresholds of three hadrons, thus understanding their origin requires knowledge of three body effects. Three particle reactions can be parameterized within the isobar model, which contain rescattering effects. We consider the one-particle exchange (OPE) process, inherent to three body scattering systems, and investigate it's analytical properties. We discuss the singularity structure of the OPE processes, and how the rescattering effects can be constructed from their successive iterations. |
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HA.00114: Simulating the Neutron Electric Dipole Moment experiment at the Los Alamos National Laboratory using COMSOL MultiPhysics Tyler Horoho The neutron electric dipole moment (nEDM) has not yet been found, but it has an upper limit of 3.0*10-26 ecm. If a neutron was blown up to the size of the earth, this upper limit is equivalent to a charge separation of less than 1 mm. The nEDM experiment at the Los Alamos National Laboratory (LANL) aims to improve this upper limit by a factor of ten. EDM in fundamental particles violates time reversal symmetry, as the particle’s magnetic dipole moment changes direction while the EDM is unchanged. EDM, if observed at the proposed sensitivity, would provide the symmetry-violating physics needed to explain the observed matter-antimatter asymmetry. I use a finite-element analysis tool, COMSOL MultiPhysics, to simulate the magnetic fields inside the experiment. Such tool is required to design the apparatus to reduce the earth field by a million fold and to create a uniform magnetic field. A highly uniform field is required to improve the measurement of the frequency shift induced by an applied electric field. The non-linear hysteresis of the mu-metal material is implemented to study how to properly demagnetize the magnetic shield. I also participate in measuring the flux of ultracold neutrons at LANL in preparation for the nEDM measurements. I will present the details of my work. |
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HA.00115: Characterization of SiPMs for COHERENT’s proposed 1-ton Liquid Argon Detector Benjamin Rand, Rex Tayloe In 2017, the COHERENT collaboration announced the discovery of coherent elastic neutrino-nucleus scattering (CEvNS) at 6.7σ via a 14-kg CsI[Na] detector stationed at the Spallation Neutron Source (SNS) in Oak Ridge National Lab. In order to demonstrate the characteristic N2-dependence of the CEvNS cross-section with high precision, COHERENT plans to deploy additional detectors that utilize different nuclei. One proposal is a 1-ton liquid argon (LAr) detector which, will also be stationed at SNS, and would collect ~5000 CEvNS events/year. One crucial decision regarding the design of this detector is whether to measure the LAr scintillation using silicon photomultipliers (SiPMs) or photomultiplier tubes. Through researching various characteristics of our proposed SiPMs such as single-pixel resolution, gain, dark count rate, and how these values change at different temperatures, we herein provide our findings for the final design of the detector. |
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HA.00116: Analysis of the γp → K+π+π-(π-)missp Photoproduction Reaction with CLAS. John H Mitchell, Alessandra Filippi The γp → K+π+π-(π-)missp photoproduction reaction was measured using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. All particles in this reaction were detected apart from a second π-, whose kinematics were determined from the missing momentum information. Invariant mass cuts were imposed on the π+π- and π+(π-) combinations to select for the intermediate K0S, so that the γp → K+K0S(π-)missp reaction could be analyzed. To obtain a clear selection, cuts were imposed on the incoming photon energy and the target fiducial volume, based on the estimation of the reaction vertex through the points of closest approach of pairs of tracks. Additionally, K0S production and decay were simulated using Monte Carlo to analyse the kinematics of a pure phase space of the particles observed in the final state. The f1(1285) meson was clearly observed using the K0S selection, with a production strength dependent on the momentum transfer. Additional activity was observed at higher energies, which calls for further inquiries into similar reactions, for instance with K0L or with charged kaons. |
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HA.00117: Analysis of MA-PMTs for a Ring Imaging Cherenkov detector Elise Aaron, Fatiha Benmokhtar, Valery Kubarovsky, Connor Pecar, Jushua W. Goodwill, Nicholaus Trotta, Waymond Smoot The mystery of sea quark distributions in the proton has led to the construction of a Ring Imaging CHerenkov (RICH) detector at the Thomas Jefferson National Accelerator Facility. RICH which will provide particle identification in the range of 3-8 GeV/c for the study of all the light sea and the strange sea contributions to proton spin. RICH collects Cherenkov photons using an array of multi-anode photomultiplier tubes (PMTs). Because their response to the low light conditions of the RICH is non-uniform, gain equalization across all PMTs requires a more sophisticated modeling technique than has |
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HA.00118: Probing for high momentum protons in 4He via the 4He(e, e'p)X reaction Courtney Boyd, Sophia Iqbal, Fatiha Benmokhtar, Konrad Aniol, Douglas Higinbotham Experimental cross sections for the 4He(e, e' p)X up to Pmiss = 0.632GeV/c at xB = 1.24 and
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HA.00119: Propagation of Vortex Beams Diffracted with Circular and Triangular Apertures Harrison Siegel Laguerre-Gaussian (LG) laser beams are called vortex beams because of optical vortices centered on the beam axis: the topological charge (TC) or number of vortices equals the index l in their eilϕ azimuthal phase term, and each photon carries a quantity lħ of orbital angular momentum (OAM). Vortex beams have immense potential for application in nuclear physics. JLab is considering generating vortex gamma ray sources, focusing vortex beams on photocathodes for polarized electron sources, and creating high power vortex beams with Fabry-Pérot interferometers to probe nuclear structure: these new tools may shed light on fundamental problems like the proton spin crisis. Here we investigate the propagation of vortex beams diffracted by circular and triangular apertures theoretically and experimentally. The properties of these diffracted beams are of interest as the diffraction patterns depend on their TC’s sign and magnitude, and can thus be used to measure their OAM directly. Simulations indicate that the diffraction patterns reach a stable state in the far field, where they become symmetrical and vortices propagate without change, and we find good agreement in our experimental results. |
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HA.00120: Analysis of Meson-Photon Interactions using Lattice QCD Benjamin Slimmer, Raúl Briceño In a variety of particle physics experiments, electromagnetic currents are used to access and probe the states of quantum chromodynamics. As a result, there is a necessity for robust theoretical calculations for reactions involving hadrons and currents in order to predict and confirm experimental observations. Presently, lattice quantum chromodynamics (lattice QCD) is the only rigorous means for studying properties of hadrons directly from the theory of quarks and gluons. Lattice QCD truncates the field theory governing interactions between subatomic particles to a finite volume of space-time points, which allows for the construction of correlation functions that describe the evolution of states. The focus of this study was on analyzing interactions in meson-photon scattering within finite volumes through analysis of kinematics for such reactions and investigation of the effectiveness of predicting coupled channel scattering amplitudes. Through the use of an artificially created “toy model” system of a coupled channel interaction, this study provides a proof of concept for calculating scattering amplitudes involving mesons and photons within lattice QCD. |
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HA.00121: Track Finding in Real and Fake Data using Machine Learning Nathan James McConnell Future Electron-Ion Collider experiments will have high rate running conditions, and it will be necessary to make quick on the fly decisions about track reconstructions. Machine learning can be used to analyze data in real time and help make these decisions. We researched techniques and tools currently in use, specifically in the LHCb experiment for rejecting fake data, Google’s TensorFlow, and the Keras TensorFlow API. We created models for data from a Hall C experiment at Jefferson Lab. An accuracy of roughly 70% was achieved by training convolutional neural networks on the data. In an effort to create data that could be easily manipulated, a program was made that creates points in 3-D space, some belonging to a track, and some being noise hits. The next steps will be to use both convolutional and recurrent neural networks to find tracks, both from real and fake data. |
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HA.00122: Studies of the Gain of Small-Pore Size Microchannel Plate Photomultipliers in High Magnetic Fields Alan McKie Rowland Microchannel plate photomultipliers (MCP PMTs) are small devices that convert light into an electric signal. These devices have many applications, but most notably in physics they are used to readout Cherenkov detectors. In the current designs of the central detector of a future Electron Ion Collider MCP PMTs will readout several Cherenkov detectors located in a magnetic field. Because of this, tests need to be conducted to determine whether the photomultipliers can retain their functionality in the magnetic field of the detector, which can go as high as 3 T. In this work we study two MCP PMTs, with pore sizes of 6 µm and 10 µm, inside a variable magnetic field. We determined that the gain of both devices would slightly increase as the magnetic field increased, until about 0.8T and 0.3T, respectively. While the gain would decrease afterwards, the photomultipliers are able to produce a signal until about 2 T. The orientation of the devices also has an effect, as the gain decreases faster for some orientations. This effect was more noticeable when the magnetic field was above 1 T. Our results suggest that photomultipliers with a small pore size are a viable option to use in the upcoming Collider in a limited range of magnetic-field magnitude. |
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HA.00123: Measurements of photon-jet correlations in pp and p+Pb collisions with the ALICE detector at the LHC Ivan Chernyshev Particle correlations are used to study jet energy loss exhibited by quark-gluon plasma (QGP) at the ALICE experiment at the LHC at CERN. I will present γ-hadron, γ-jet, and π0-jet correlations of pp and p-Pb taken by the ALICE experiment. The photons used in the γ-hadron study were isolated direct photons, which have few other particles nearby. To separate single photons from pairs of photons from meson decays, I analyze the shape of the energy deposited in the ALICE electromagnetic calorimeter. I used two methods - a deep neural network, and rejecting clusters with higher RMS shower energy along the major ellipse axis. Correlation functions are normalized by the number of triggers, and conditional yields of hadrons and jets are shown as a function of the difference in azimuthal angle. π0-jet and γ-jet correlations are studied with a variety of observables, including a new observable designed to measure a parton’s momentum as a fraction of that of a lead nucleus. The results are compared to event-generators and will eventually be compared with similar results from PbPb, which produce more QGP than p-Pb collisions. We aim to assess the mechanism of jet energy loss in QGP, and constrain the gluon densities in heavy nuclei. |
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HA.00124: Coherent CAPTAIN-Mills: Measuring Low-Energy Neutrino Cross Sections at Los Alamos Neutron Science Center Jose Plata Salas, Richard G Van de Water, William Charles Louis, Robert L Cooper Core-collapse supernovae (SN) release 99% of their gravitational binding energy in neutrinos with energies of a few tens-of-MeV over a timescale of a few tens-of-seconds. The flavor composition, energy spectrum and time structure of the neutrino burst in a SN explosion provide information about the supernova properties, including its core-collapse, explosion and neutron star cooling mechanism. Coherent CAPTAIN-Mills (CCM) is a Liquid Argon (LAr) detector located at the Lujan Center at the Los Alamos Neutron Science Center which is a prolific source of neutrinos up to 50 MeV from stopped pion and muon decay. By instrumenting CCM with photo-multiplier tubes (PMTs) and fast electronics, a significant measurement of low-energy neutrino scattering cross sections can be performed. We propose to use the CCM detector to measure the νe and νμ nuclear cross sections on liquid argon with an uncertainty of roughly 10%, focusing on the supernova energy range. This poster discusses the importance of the measurements of low-energy neutrino cross sections for the observation of supernovae explosions, as well as the PMT background rate and energy distribution, status of the detector and Fall commissioning run. |
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HA.00125: CAPTAIN-Mills: A Sterile Neutrino Search using νμ Disappearance at the Los Alamos Neutron Science Center Nicholas W Kamp, Robert L Cooper, William C Louis, Richard G Van de Water When combined with results from the Liquid Scintillator Neutrino Detector (LSND), the most recent MiniBooNE results confirm an excess of νe charged-current quasi-elastic events at the 6.1σ level. This could be explained by the existence of a fourth neutrino mass eigenstate. To test this hypothesis, the CAPTAIN-Mills (CCM) experiment has been funded to run at the Lujan Center at the Los Alamos Neutron Science Center. CCM will use a 7700 L liquid argon detector to observe coherent elastic neutrino-nucleus scattering (CEνNS) using scintillation light. MiniBooNE provides evidence for both νe and $\bar{\nu_e}$ appearance; however, experiments at the GeV and TeV energy scales have not yet observed νμ disappearance. CEνNS is a neutral current interaction with an order-of-magnitude enhanced cross section at lower neutrino energies over other ν-Ar interactions. Thus, the 30 MeV muon neutrinos from the stopped pion source at the Lujan Center will make CCM the first experiment sensitive to νμ disappearance at the LSND energy range. Further, the 6.0 × 10-6 duty factor of the source will be essential in constraining neutron backgrounds. This poster focuses on the motivation of CCM and the status of this Fall's commissioning run. |
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HA.00126: Time-Reversal Analysis of Neutron Optics Components in the NOPTREX ExperimentHajer Dhahri, NOPTREX Collaboration Hajer Dhahri By the CPT theorem, the search for new sources of time reversal ($T$) violation in particle interactions is crucial to our understanding of charge-parity ($CP$) violation, which is required to explain the matter-antimatter asymmetry of the universe. The aim of the Neutron Optics Time Reversal Experiment (NOPTREX) is to search for $T$-violation in the transmission of polarized neutrons through polarized heavy nuclear targets such as $^{139}$La, which have large measured parity-violating resonances in neutron transmission. The development of quantum mechanical time evolution operators for each individual component of our apparatus is particularly critical for analysis of our experimental sensitivity to time-odd observables, and elimination of systematic errors through the Time Reversal Invariance Violation transmission theorem\cite{Bowman}. We will focus our discussion on the calculations of time evolution operators, including propagation through a magnetic field of the spin flipper, which we mapped at FP12, LANSCE. \bibitem{Bowman}, Bowman, Gudkov, Phys. Rev. C. {\bf 90}, 065503 (2014). |
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HA.00127: Improving Accuracy of Parity Violation Measurements for NOPTREX Experiment at LANLDANIELA OLIVERA, Berea College for NOPTREX collaboration. Daniela Olivera The main goal of the Neutron Optics Time Reversal Experiment is to look for new sources of time reversal (T), which could explain the matter/antimatter asymmetry in the universe. As part of our search, we need higher (within 1\%) accuracy measurements of the parity violating spin-dependent forward neutron scattering amplitude in La-139 \cite{Yuan} and other nuclei, which share the same matrix element as time-reversal odd amplitudes. Since lanthanum has a large (~10\%) PV transmission asymmetry, we can use it as both the polarizer and analyzer, which eliminates the measurement of the neutron polarization and associated systematic uncertainties that accompany the use of a traditional 3He polarizer. This presentation will discuss the analysis of the beam intensity profiles (necessary to calculate the neutron spin-flip efficiency) and the fitting of the nuclear resonance data collected in Summer 2018 at Los Alamos National Lab, including the effects of Doppler broadening on the resonances. \bibitem{Yuan} Yuan, Bowman, et al., Phys. Rev. C. {\bf 44}, 2187 (1991). |
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HA.00128: Spin Transport of Polarized Helium-3 Atoms. Rhett Alston Croley The electric dipole moment of the neutron, a property that has never been observed, would predict the violation of time reversal symmetry necessary to explain the existence of matter in our universe. A vital component of our experiment measuring this exotic property is an atomic beam of polarized Helium-3, which serves as a co-magnetometer in the precession chamber. Recent changes to simplify the geometry of our experimental apparatus have affected the magnetics of injecting polarized Helium-3 into the collection volume. We present a redesigned tapered magnetic field for this new optimized design. As the Helium-3 atoms travel ballistically along the tapered B field, they precess at the Larmor frequency and adiabatically follow the direction of the field. Our goal is to taper from high field to low field as quickly as possible, while keeping field distortions low enough to maintain the polarization. We also present our Monte Carlo simulation which tracked the spin precision of individual Helium-3 atoms to optimize the magnetic coil performance |
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HA.00129: Development of gamma ray detectors for the parity violation NDTGamma experiment. Diana Sahibnazarova, Christopher B Crawford, Mark McCrea, Michael Snow, John Vanderwerp For the NDTGamma Experiment, the goal is to measure the directional asymmetry in the gamma-ray emission from the reaction n+D->T+gamma (6.2 MeV). The gamma ray direction emission will be measured using an array of 100 CsI scintillators attached to photomultiplier tubes (PMTs). To test the individual PMTs to be used in the NDTGamma experiment a dark box was used with a Co-60 gamma-ray source. The current output from the PMTs was examined both for the dark current without a gamma-ray source as the high voltage was increased, and with the Co-60 source to ensure that the PMTs were functioning. Additionally, the outcome impulses of the cathode and anode currents were examined. The decrease of the noise in the PMT output was investigated. Designs were investigated for mounting the PMTs to the scintillators. The scintillators processes, PMTs functioning, testing methodology, and results will be presented. |
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HA.00130: Neutron Yield and Pulse Shape Characterization of a DD Dense Plasma Focus Source Emrys Peets Dense Plasma Focus devices generate fusion reactions through the rapid ionization of the deuterium gas. This ionization and propagation process forms a plasma pinch near the anode in the device. In a deuterium - deuterium DPF, fusion reactions created during the pinch generate a short ≤ 100ns burst of 2.45MeV neutrons. These devices are at the forefront of industrial and military innovation, with applications to nuclear astrophysics and national security. A DD DPF source, located in Albuquerque, NM, has an estimated yield of 10^12 2.45MeV neutrons per pulse as determined by silver activation. This study aims to characterize the pulse shape of the DD source, and also provide confirmation of the neutron yield. Plastic scintillators, coupled to silicon photomultipliers or PMTs are the primary means of pulse shape measurement in this experiment. Additional activation foils read with high purity germanium detectors provide yield information. Bubble dosimeters of varying sensitivity are used to measure the dose and reproducibility from this pulsed source. With these methods of detection, we provide further insights into the capabilities of DPF devices, fusion research, and neutron detection methods. |
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HA.00131: Testing the electronics for the Nab Experiment at SNS Thomas Bailey, Leah J Broussard, Mark Makela, Erick C. Smith, Aaron P Sprow, Albert R. Young, for the Nab Collaboration ORNL The Nab experiment at the SNS is designed to measure the values of the beta neutrino correlation and Fierz interference terms in neutron β-decay using a cold neutron beam. These two parameters provide critical input for tests of the standard model of particle physics which probe for new physics at energy scales higher (in some scenarios) than those achievable at the Large Hadron Collider. To make these measurements we have developed 1.5-2 mm thick silicon detectors with ~11.5 cm diameter active regions divided into 127 hexagonal pixels operated as reverse-biased diodes. A Field Effect Transistor (FET) front end and two stages of amplification convert the integrated charge into energies of incoming particles into voltage signals read into the Data Acquisition System (DAQ). A new circuit was designed to simulate pulses from charged particles to characterize the performance of the electronics. Using this with the DAQ sped up the testing process by a factor of 30 from a benchtop setup. Initial results provide a range in which the response signal is directly proportional to the incoming particle’s energy, and reveals at what point the FETs become saturated. |
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HA.00132: Magnetic Field Analysis and the Calculation of the Spin Flip Efficiency Lillie Cole, Danielle Schaper Parity Violation (PV) was first observed in weak decays of 60Co by C.S. Wu et al in 1956 and has since been observed in many other systems. The Neutron Optics Time Reversal Experiment (NOPTREX) Collaboration is attempting the most precise measurement of parity violation present in a nuclear resonance by examining the 0.734 eV resonance in 139La using a ‘double lanthanum’ technique (see Yuan et al., ref \cite{Yuan}) wherein unpolarized neutrons are incident upon two unpolarized lanthanum targets; the first target weakly polarizes the beam and the second target acts as an analyzer. Magnetic field coils were installed to both preserve the neutron polarization and to flip the neutron spin. A thorough understanding of the uncertainties in the experiment are critical to receive a precision measurement, one such value is the spin-flip efficiency. This poster will discuss the magnetic field mapping process, its subsequent analysis, and how it folds into the spin-flip efficiency calculation. \bibitem{Yuan} Yuan, Bowman, et al., Phys. Rev. C. {\bf 44}, 2187 (1991). |
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HA.00133: Testing and constructing BAND, a backward angle neutron detector for CLAS12. Anjali Nambrath, Efrain P Segarra, Reynier Cruz Torres, Florian Hauenstein, Arie Beck, Sharon Beck, Lawrence B Weinstein, Axel W Schmidt, Or Hen The Backward Angle Neutron Detector (BAND) is a scintillator array planned to be part of the CLAS12 detector at Jefferson Lab. BAND is specifically designed to detect recoiling spectator neutrons in deep inelastic scattering collisions between the accelerated electron beam and protons in deuterium nuclei, with the goal of understanding the structure functions of these bound protons. Scattering events with fast-moving neutrons emitted at large angles relative to the momentum transfer imply the deuteron was in a short-range correlated (SRC) configuration before the collision. BAND will be positioned upstream of the CLAS12 target and will cover scattering angles from 160° to 170°. Time-of-flight will be used to determine neutron momenta within an uncertainty of 1.5%, given BAND’s expected 300ps time resolution. This will clarify the relationship between modification of the structure function and nucleon virtuality, and could impact present understanding of the EMC effect and its relation to nucleons in SRC configurations. I will present the methods used to test BAND’s components and complete its assembly. |
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HA.00134: PMT and Scintillator test for BAND. Oluwaseun Emmanuel Ogunde, Efrain P Segarra, Arie Beck, Sharon Beck, Axel W Schmidt, Or Hen The BAND experiment, which will run in Hall B at Jefferson Lab, will test the hypothesis that the EMC effect stems from the modification of short-range correlated (SRC) nucleon pairs. In the experiment, an 11 GeV electron beam will scatter from a deuterium target, with a Backward Angle Neutron Detector (BAND) tagging recoil spectator neutrons. The neutron momentum can indicate the configuration of the deuteron prior to the collision. However, measuring the momentum of an uncharged particle requires high precision timing. In this poster I present the methods by which I tested the photo multiplier tubes and scintillating plastic bars that were being assembled into BAND’s constituent modules. A fast LED was employed to measure PMT gain, PMT time resolution, and scintillator attenuation length, to ensure the quality of the components used in the final assembly. BAND will undergo commissioning tests this fall, with first production data scheduled for early 2019. BAND will make a definitive statement about the role of SRCs in the EMC effect. |
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HA.00135: OLIVIA Experiment Simulation Kristen Marie Surrao OLIVIA (Optical Lithium V-Minus-A) is a low energy, high precision experiment that aims to search for physics beyond the Standard Model. In particular, it will use an optical TPC to study Li-8 beta decay in order to search for non-standard interactions in the electroweak sector. This will be done by performing a kinematically complete measurement that will allow extracting the beta-neutrino angular correlation coefficient. Unlike traditional experiments, which rely on ion trapping, the use of an optical TPC will allow a significant increase in statistics, which will also improve systematics. This work focuses on results of a Monte Carlo simulation study of OLIVIA using the Garfield++ software package, with emphasis on optimization of decay kinematics reconstruction. |
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HA.00136: Software to Monitor CLAS12 Data Quality Ben Seth Weinstein, Alexander R Balsamo, Gerard P Gilfoyle The physics program at Jefferson Laboratory will probe the quark sub-structure of the nucleus with the Continuous Electron Beam Accelerator Facility (CEBAF). We use the CEBAF Large Acceptance Spectrometer (CLAS12) to measure the charge, momentum, and energy of particles produced by electron-nucleus collisions. We are developing software to monitor data quality from the analysis of a scheduled experiment that will measure the neutron magnetic form factor (GnM) among at least six other experiments. The monitoring code was written with a java-like scripting language called groovy and uses the CLAS12 Common Tools. To test the code we generated quasielastic events and simulated the CLAS12 response with the Monte Carlo code gemc. The events were reconstructed and analysed to extract monitoring observables. For example, we obtained the electron sampling fraction as a function of run number. The sampling fraction is the energy deposited in an electromagnetic calorimeter divided by the momentum and is expected to be constant. We will show simulations of the sampling fraction, ratio of protons to electrons and other quantities versus run number. |
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HA.00137: Shear Viscosity to Entropy Density Ratio of Quark Gluon Plasma at Finite Baryon Densities Emma McLaughlin, Jacquelyn Noronha-Hostler The Quark Gluon Plasma, which is measured experimentally in relativistic heavy ion collisions, behaves as a near perfect fluid where the shear viscosity to entropy density (η/s) ratio approaches zero. Relativistic viscous hydrodynamic calculations have been extremely successful in describing the flow of the Quark Gluon Plasma, thus, confirming the nearly perfect fluid paradigm at zero baryon density. Current experiments at the Relativistic Heavy Ion Collider (RHIC) are now probing finite baryon densities where the η/s of the Quark Gluon Plasma remains unknown. In this study, we use the Hadron Resonance Gas (HRG) model to calculate η/s at low temperatures (between T=100-155 MeV) and at finite baryon densities. We use the most state-of-the-art Particle Data Group list (PDG16+) and incorporate interactions by comparing excluded volume corrections and repulsive mean field calculations. We find a suppression of η/s at large baryon densities, which would be expected in the absence of a critical point. |
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HA.00138: Calculation of strangeness asymmetry in the proton sea Chase Kim The Heisenberg uncertainty principle allows the proton to have a strange sea, by way of splitting into a K or K* meson and a Lambda or Sigma baryon. The net strangeness of the proton is zero, but the splitting gives rise to an asymmetry in the momentum distributions s(x) and sbar(x) of the strange and anti-strange quarks. Our goal is to understand this asymmetry in terms of the splitting process and the structure of the mesons and baryons. We determine the momentum distributions with both a Meson Cloud Model (MCM) and a Light Cone Model (LCM). We use the MCM for the fluctuation functions f, which represent the probability that the proton will split into a meson-baryon pair. We use the LCM to calculate the parton distribution functions (PDFs) for the strange quarks in the meson and baryon in terms of two-body wave functions. Then s(x) and sbar(x) are found from a convolution of the splitting functions f and the meson and baryon PDFs. We find that the strangeness asymmetry s(x)-sbar(x) has two crossings, or changes of sign. We study the dependence of the asymmetry on the parameters of our model, and compare our results to global PDF analyses and experimental constraints on proton strangeness. |
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HA.00139: Understanding Radon Mitigation through Vacuum Swing Absorption Gabriel Wieczorek, Richard William Schnee, Joseph Street Radon is a noble gas that undergoes radioactive decay which can be problematic for dark matter search experiments. Therefore, filtration is needed in order to prevent radon daughters from attaching themselves to the detector during assembly. The filtration process involves flowing outside air (relatively high in radon) through large tanks of carbon. The filtration system at the South Dakota School of Mines and Technology has shown radon reduction over 3000x, with concentrations as low as 20 mBq/m3. This same system has been used as a radon mitigation model for both the LZ and SuperCDMS experiments. In order for further understanding and optimization of radon mitigation, a smaller “Table-Top” system is being commissioned. This system will be used to study the effects of radon passing through carbon under various parameters such as tank volume, flow rate, temperature, pressure, and relative humidity. |
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HA.00140: Exclusive π0 production and Compton scattering at GlueX Zachary Allen Baldwin In this work, studies of the reaction γp->π0p will be presented along with an exploratory study of the Compton scattering process γp->γp. These reactions were studied by utilizing the fine-grained calorimetry of the GlueX experiment in order to aid in the understanding of production mechanisms in high-energy photoproduction. The separation of π0 and Compton events is challenging due to potential merging of the π0 decay photons into a single shower for large polar angles and high momentum. This merging causes small angle π0 decay photons to look like Compton photon showers. As a result, electromagnetic shower shape variables are used to study these effects, and with the introduction of three new width variables, comparisons between data and Monte Carlo samples are obtained to estimate the signal purity for these two reactions. These results will provide a stepping stone to ultimately measure the Σ beam asymmetry for large angle Compton scattering events. |
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HA.00141: Study of the Background in Search for the Chiral Magnetic Effect in Heavy-Ion Collisions with the AMPT Model Arnav Ramkrishnan The chiral magnetic effect (CME) arises from the chirality imbalance of quarks and its interaction to the strong magnetic field generated in non-central heavy-ion collisions. Possible formation of domains of quarks with chirality imbalances is an intrinsic property of the Quantum ChromoDynamics (QCD), which describes the fundamental strong interactions among quarks and gluons. Azimuthal-angle correlations have been used to measure the magnitude of charge-separation across the reaction plane, which was predicted to arise from the CME [1]. However, backgrounds from collective motion (flow) of the collision system can also contribute to the correlation observable. In this poster, we investigate the magnitude of the background utilizing the AMPT model [2], which contains no CME signals. We calculate the charge-separation observables and the background correlations in Au+Au collisions at 200 GeV and U+U collisions at 193 GeV, which provides a background baseline for the experimental data. |
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HA.00142: Glauber Model Monte Carlo Simulations of Pb+Pb and p+Pb Collisions at 5.02 TeV Ariana Caiati The Glauber Model is widely used in relativistic heavy ion physics to calculate basic quantities such as impact parameter, number of participating nucleons, and the number of collisions, which are related to the geometry of the colliding nuclei. The Woods-Saxon probability density function is used to model the locations of the nucleons within the two nuclei and a Monte Carlo method is used to generate a random distribution of impact parameters. In order to use these calculations to determine the collision centrality for Pb+Pb and p+Pb collisions, a negative binomial distribution is used to relate particle production and transverse energy measurements to the number of nucleon-nucleon collisions. Comparing the measured distribution of transverse energy to the predictions from the Glauber Monte Carlo allows the centrality classes to be defined and the trigger efficiencies for peripheral events to be determined. This project will allow the study of quarkonia production from small nuclear systems up to the most central heavy-ion collisions in order to disentangle cold nuclear matter effects from those related to the color deconfined Quark-Gluon Plasma. |
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HA.00143: Isolated Direct Photon Measurements in Au+Au Events with the sPHENIX Detector Chase Smith, Francesco Vassalli The sPHENIX experiment at the Relativistic Heavy Ion Collider will be a new detector which will measure heavy particles, photons, and jets created in high energy heavy ion collisions. One of the goals of this experiment is to use photon-jet pairs to further our understanding of the strongly interacting Quark Gluon Plasma created in Au+Au collisions. We benchmark the capability for reconstructing, identifying, and isolating high energy photons which are created during the hard subprocess, known as direct photons, in high multiplicity Au+Au events. In this study Pythia8 events with a high-$p_{T}$ photon were embedded into central Au+Au \textsc{Hijing} events and a full \textsc{Geant}4 simulation of the detector was performed. We develop and test a technique, which uses the sPHENIX calorimeters, to isolate reconstructed photons from jet fragments in the high multiplicity nuclear background. |
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HA.00144: Realistic equation of state for QCD with a critical point Paolo Parotto, Marcus Bluhm, Debora Mroczek, Marlene Nahrgang, Jacquelyn Noronha-Hostler, Krishna Rajagopal, Claudia Ratti, Thomas Schäfer, Mikhail Stephanov We combine state-of-the-art lattice QCD calculations with expected critical behavior to produce a family of equations of state. Each equation of state matches available lattice results and contains a critical point from the 3D Ising model universality class. The position of this critical point can be chosen in the range of chemical potentials covered by the second Beam Energy Scan at the Relativistic Heavy Ion Collider (RHIC). Our results for the pressure, entropy density, baryon density, energy density and speed of sound can be used as inputs in hydrodynamic simulations of heavy ion collisions. In the future, comparisons between RHIC data and the output of the hydrodynamic simulations built upon the quations of state that we have constructed may be used to locate the critical point in the QCD phase diagram, if there is one to be found. |
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HA.00145: Self-Learning Proposal Machines for Fermionic Monte Carlo Simulations Siddhartha Harmalkar, Andrei Alexandru, Paulo Bedaque, Scott Lawrence, Daniel Lay, Gregory Ridgway Despite the unparalleled applicability of Markov Chain Monte Carlo methods to sampling probability distributions which arise in a large number of problems in statistical physics, the resources required to obtain independent samples from the distributions related to problems of interest often becomes intractably large. This issue emerges notably in simulations of fermionic systems. Recently, the use of machine learning has been suggested as an approach to accelerate Monte Carlo simulations through the construction of “trained” non-local recommendation machines which can generate proposals of statistically independent samples in a tractable manner that can then be sampled from in such a way as to obtain unbiased samples from the probability distribution of interest. Here, we present such a machine to accelerate fermionic systems in general and apply it to study Quantum Electrodynamics in 1+1 dimensional spacetime. |
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HA.00146: Hadronization in Forward Jets in p+p collisions at √s = 8 TeV and 13 TeV Jem Guhit, Christine A Aidala Hadronic jet production at high energy colliders is an important testing ground for Quantum Chromodynamics (QCD) because the coupling constant for the hard interaction becomes smaller at high energies which facilitates perturbative theoretical calculations. The capabilities of the Large Hadron Collider beauty (LHCb) experiment in jet reconstruction with complete particle identification provide a unique and unprecedented opportunity to study the process of hadronization. This study initially explores various multi-differential observables to quantify hadron production in forward jets with LHCb kinematics. Simulated p+p collision datasets at √s = 8 TeV and 13 TeV within 2.5 < η < 4.5 were presented in this research. The dynamic variables examined include the relationship of jet energy vs. jet transverse momentum, production of kaons in jets, the momentum fraction (z), transverse momentum of a particle relative to the jet axis (jT), and joint distribution (z vs. jT) in charged particles, neutral particles, baryons, and mesons. We looked at the correlations and trends from the observables for different energies in the simulated data in order to understand what correlations may be feasible and valuable to study in a future analysis based on real data. |
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HA.00147: Helicity Asymmetries in γd → ppπ- Rescattering Events Andrew Dunton The strong force is one of the fundamental forces of nature, yet many of its features are still not yet well understood. We learn about it by investigating the interactions between various hadrons. One method to study how shortly-living hadrons interact with nucleons is via final-state interactions, where a hadron produced by a beam incident on a nucleon in a nucleus scatters off another nucleon. By measuring hadro-production off a deuteron target, information about the second interaction is gained. In this project, we analyzed data collected in the E06-103 experiment at Jefferson Lab, where a circularly-polarized photon beam was incident on a deuteron target. Our objective is to extract the beam-helicity asymmetry of the γd→ppπ- reaction and establish how it depends on kinematics. To maximize sensitivity to pπ- and pp final-state interactions, we select an event sample where both protons carry high momenta. We observe large helicity asymmetries for specific energies and angles of scattered particles. Here we discuss how these can be used to identify kinematics where specific final-state scatterings dominate. The methods we developed will be applied to the study of hyperon and J/psi final-state interactions. |
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HA.00148: Radon Decay Simulation and Background Analysis of the MAJORANA DEMONSTRATOR Experiment Brady Bos The Majorana Demonstrator neutrinoless double-beta decay experiment is operating at the Sanford Underground Research Facility to demonstrate the required background and scalability of a Ge-based, ton-scale experiment. It consists of two cryostats of HPGe detectors enriched in the isotope 76Ge within a graded shield containing low-background gamma and neutron shielding materials, a sealed purge volume, and an active muon-veto system. Our initial results show we have achieved low backgrounds and we are now developing a full background model based on Monte Carlo simulations and available data. A purge system delivers LN2 boil-off to the shield volume to mitigate the entry of Rn from the surroundings. A validation between simulations and high-Rn commissioning data is based on an improved determination of the source of decays. Further, the purge flow has been modeled and combined with the new simulations to estimate the Rn background. The details of the simulations, the effectiveness of the purge system, and an analysis of the Rn backgrounds will be presented. |
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HA.00149: Characterization of Nab Detector Timing Systematics Using Monte Carlos Simulations Derek D Holman, Joshua B Hamblen, Aaron P Sprow The Nab Experiment at the SNS in Oak Ridge National Lab aims to measure the electron-neutrino correlation parameter, a, in free neutron beta decay with a precision of Δa/a ≤ 1E-3 using direct measurement of the phase space distribution of the resultant electron energy and proton momentum. The allowable timing systematic, Δtproton-electron, must be less than a 300 ps deviation from the average to meet this goal. In measuring tagged particles, particularly electrons, across a broad range of energy, we can gain an understanding of how the detector physics will affect the timing measurement and set a limit on Δtproton-electron. Electron-capture sources produce fixed energy electrons with a well-understood "tag" from coincidence photons. Using a fast CeBr3 scintillator with a SiPM readout, we can measure the systematic effects associated with the Nab silicon detectors. We present here an analysis of Monte Carlo simulations for 139Ce, 133Ba, and 113Sn decays, and discuss the application of these results to the experiment as a whole. |
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HA.00150: 30kV Proton Accelerator with Ultra High Flux Stability Stefan Baessler, Albert Bryant
In my poster I will describe a low energy proton accelerator with ultra high flux stability which is being developed at UVa. In this accelerator we send an electron beam to ionize hydrogen gas which produces protons and molecular hydrogen ions. The ions are accelerated and then mass selected by a magnetic field before being detected. In previous work, the accelerator had shown a stability of 170±360ppm/h. Currently, the accelerator is being improved to increase its count rate and maintain or improve the stability to below 100ppm/h. One of the purposes of this proton accelerator will be to characterize proton detectors in the Nab collaboration which is presently being installed at the Spallation Neutron Source (SNS) at Oak Ridge National Lab . |
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HA.00151: Some preparations for the LZ direct dark matter detector Oliver A Hitchcock, Kimberly J Palladino LUX-ZEPLIN (LZ) is a next generation dark matter direct detection experiment that will operate at the Sanford Underground Research Facility (SURF). With a dual-phase xenon scintillation detector and an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with Weakly Interacting Massive Particles (WIMPs), a hypothesized dark matter candidate. In addition, a series of system test prototype vessels will be used for testing key LZ design aspects and critical components. The culmination of these, Phase-II, will test the final LZ grids in gaseous xenon, investigate electron emission at operational fields, and provide the final assurance of the TPC meeting high voltage requirements and goals. Furthermore, UW-Madison is responsible for producing photomultiplier-tube signal and high voltage cables at the UW Physical Sciences Laboratory under a strict cleanliness protocol to ensure minimal introduction of radon and other contaminants that could fake a WIMP signal. With construction well underway, LZ is on track to start collecting data in 2020. |
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