Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session QA: Conference Experience for Undergraduates Poster Session VI (5:20pm - 5:55pm) |
Hide Abstracts |
|
QA.00001: Exploring the Physics of Neutron-Unbound Nuclei Produced from Ne-28 and Ne-29 Fragment Beams Alaura Cunningham Experimental studies of neutron-unbound systems provide important input to aid the development of theoretical models that describe exotic nuclei. In 2016, the MoNA Collaboration performed an experiment at the National Superconducting Cyclotron Laboratory to measure the half-life of O-26. The Coupled Cyclotron Facility provided a 140 MeV/u Ca-48 primary beam that impinged on a beryllium target to produce F-27, Ne-28, Ne-29, and Na-30 secondary beams. The analysis of the recorded data focused on events in which the two-neutron decay of O-26 produced from the F-27 secondary beam was measured. As such, a large fraction of the dataset is unused. The current project aims to extract the decay energy spectra for neutron-unbound systems produced from the Ne-28 and Ne-29 beams and compare them to previous measurements while also searching for new neutron-unbound states. In particular, measurements of one- and multi-neutron coincidences with F-25, F-24, or O-22 fragments produced from the Ne-28 beam and F-27, F-26, O-24, or O-22 produced from the Ne-29 beam will be compared to previous studies. [Preview Abstract] |
|
QA.00002: Using Potassium-40 to Study the Radiogenic Heating of Exoplanets Lauren Ulbrich The radioactive decay of isotopes is an integral part of the heating of a planet's mantle, and is connected to continent formation and tectonic plate activity, which planetary scientists consider necessary for a habitable environment. One of the key isotopes that is known to drive radiogenic heating on Earth is $^{40}$K. Recently, our group constrained experimentally for the first time the destruction rate of $^{40}$K through the measurement of the $^{40}$Ar(p,n)$^{40}$K reaction rate at Ohio University. A new experiment to further constrain the destruction rate of $^{40}$K by studying the $^{37}$Cl($\alpha$,n)$^{40}$K reaction is being planned to reduce nuclear physics uncertainties in the production of $^{40}$K. In preparation, we performed post-processing reaction network calculations to estimate the sensitivity of $^{40}$K production to the relevant reaction rates. From our final results, we expect to inform studies of radiogenic heating in exoplanets. [Preview Abstract] |
|
QA.00003: Machine learning techniques for track analysis in Active-Target Time Projection Chamber data Lexanne Weghorn, Michelle Kuchera, Raghu Ramanujan, Morten Hjorth-Jensen, Daniel Bazin, Yassid Ayyad The ${}^{22}$Mg($\alpha$, p)${}^{25}$Al reaction rate is an important reaction in the study of Type-I X-ray bursts. The Active-Target Time Projection Chamber (AT-TPC) was used to study this reaction at the National Superconducting Cyclotron Laboratory. Classifying the reaction types for each event of this experiment proved extremely challenging due to experimental conditions and algorithmic limitations. This work proposes the use of machine learning techniques as a method for determining the number of reaction products in a single event. This can act as the first step in classifying reaction types in this experiment. Both fully connected neural networks (FCNNs) and convolutional neural networks (CNNs) were explored to motivate their use for analysis of the data. Preliminary results with simulated data indicated that FCNNs and CNNs can both predict the number of reaction products in an event. These results will be presented and discussed. [Preview Abstract] |
|
QA.00004: Painting Scintillator Tiles for the STAR Forward Upgrade Madison Meador Over the past 20 years, the Solenoidal Tracker at RHIC (STAR) at Brookhaven National Laboratory has been a leading experiment investigating the complex structure of nucleons through high energy collisions of proton beams. Recently, STAR has begun construction on the “Forward Upgrade,” which will enable charged-particle tracking and calorimetry measurements at very close proximity to the beam line (2.5$<$\eta$$<$4). Approximately 18,000 plastic scintillator tiles are needed to construct the Hadron Calorimeter (HCal). The manufacturing effort is shared across several institutions, including OSU, UCLA, and Valparaiso University. Abilene Christian University$'$s (ACU) contribution to the construction of the HCal includes machining, polishing, and painting approximately 7200 of these tiles. A painting process was developed to accommodate the specific requirements of the HCal, utilizing newly renovated lab facilities at ACU. To validate the procedure, we measured the wavelength of light absorbed by the scintillator tile as a function of paint thickness. These data will be presented in the poster, along with the details of the painting process. [Preview Abstract] |
|
QA.00005: A Jet Shape Study with STAR Moshe Levy Quark-Gluon Plasma (QGP) is a state of matter comprised of quarks and gluons that are not confined within any particular hadrons. QGP is expected to be produced in ultra-relativistic heavy ion collisions at RHIC and the LHC. In this analysis, we study properties of the QGP produced in these collisions with internal probes such as jets. Jets are collimated sprays of hadrons that originate from hard scatterings of quarks and gluons (partons). Modification of the jets due to jet quenching, i.e. redistribution of jet energy, has been observed in heavy ion collisions as jets traverse the medium before reaching our detectors. To study this in detail, we utilize data collected by the STAR experiment located at RHIC, and we compare jets produced in Au+Au collisions to those created in p+p collisions. Specifically, we look at three jet shape observables: LeSub, g, and ptD to get a complementary picture of how the medium modifies the jet. [Preview Abstract] |
|
QA.00006: Implementing a Uranium Fission Insert at the LANL Ultracold Neutron Source Richard McDonald The spallation ultracold neutron source at the Los Alamos Neutron Science Center produces ultracold neutrons (UCNs) with a kinetic energy below 340 neV. Ultracold neutrons are subject to different systematic effects than their cold neutron (0.025 eV) counterparts. This low-energy state of neutrons can be stored and transported to experiments in the laboratory. These observations are critical in answering fundamental queries in physics such as the nature of dark matter and matter/anti-matter asymmetry in the universe. At the moment these experiments are statistically limited, as the current UCN source produces an unpolarized storable density of 180 UCN/cc. Adding a 20{\%} lightly enriched uranium insert to induce nuclear fission reactions has the potential to increase the production of UCNs anywhere from a factor of 2-8. We will present the results of an optimization of the uranium insert geometry to enhance UCN production while ensuring it remains subcritical and heating contributions are manageable through the use of the Monte-Carlo Neutron Particle code (MCNP6). [Preview Abstract] |
|
QA.00007: ~ Nuclear Isomer Gamma Emission Simulations in Geant4~~ Andrea Bracamonte ~Nuclear isomers have a wide variety of applications, yet many properties, such as energy levels, are not well known. Energy levels are experimentally determined by detecting gamma emission from nuclear de-excitation. Through Monte Carlo simulations, this process has been simulated using various beam and target combinations in Geant4. A detector ring consisting of multiple scintillation detectors has been placed in optimal positions to specifically measure energy from gamma emissions. Using the analysis capabilities of CERN's Root, various physical phenomena have been observed. Since energy levels of neutron-rich isomers are not well identified, excitation states are of~particular interest~to better develop nuclear structure models.~~ [Preview Abstract] |
|
QA.00008: Non-Linear Behavior in Plastic Scintillator Neutron Detectors Andrea Munroe, Jeremy Hallett, Warren Rogers The MoNA Collaboration investigates the decay of exotic neutron-rich nuclei near the dripline using an array of 144 2-meter long scintillator bars with photomultiplier tubes attached to the ends. The energy and momenta of decay neutrons are determined by hit location in the array and time-of-flight. Accurate determination of decay energy is limited by position and time resolution in the bars. Anomalies in cosmic muon positon spectra from an experiment we conducted at LANSCE (Los Alamos Neutron Science Center) point to non-linear behavior in the detector. We have conducted a series of measurements using cosmic muons in a MoNA detector to develop a map of physical positon to its location in time-difference spectra, and have discovered that the non-linearity is due to waveform shape variations along the bar's length, resulting from light reflection at the ends. We have created an algorithm that corrects for this non-linear mapping of position. Results from our analysis can be used to improve the design of future scintillator-based detector arrays. Work supported by NSF grant PHY-2012511 [Preview Abstract] |
|
QA.00009: Improvements In Laser Circular Polarization for Optical Pumping Anastasia Afanassieva, John Behr TRINAT (TRI{\scriptsize UMF}’s Neutral Atom Trap) uses spin-polarized $^{37}$K nuclei to make precision measurements of nuclear beta-decay asymmetry with respect to spin [Fenker et. al Phys. Rev. Lett. 120, 062502 (2018)]. This poster outlines techniques in improving the circular polarization of the optical pumping light used to polarize the spin of trapped nuclei. Commercially available Twisted Nematic Liquid Crystals (TNLC) are able to quickly flip light polarization between two states. The TNLC yielded a circular light polarization $S_3$ = 0.99996 $\pm$ 0.00003 as defined by Stokes Parameters. This is a significant improvement from the previous liquid crystal device used which gave a circular polarization between $S_3$ = 0.9931 and 0.9997. The poster will also look at the use of Quarter Wave Plates for light circular polarization. There is also a discussion on how the quality of polarization can be improved by an additional mechanically rotating linear polarizer. When combined with a demonstrated 3 times increase in laser power, the improved circular polarization of the light resulted in a predicted improvement in the nuclear spin polarization from 0.9913 $\pm$ 0.0009 to 0.9970. The circular light polarisation is no longer a limiting effect in the nuclear spin polarization. [Preview Abstract] |
|
QA.00010: Materials Screening with High Purity Germanium Detectors Kevin Marquez Diaz Rare event experiments such as those searching for neutrinoless double beta decay and dark matter must face the challenge of inherent radioactivity in materials used to construct detectors and shielding, such as copper, lead and steel, in order to meet background goals. Gamma ray spectroscopy with high purity germanium (HPGe) detectors is an important tool to screen materials for such experiments. In this work, we will compare the performance of two HPGe detector systems, one operated at sea level and one operated underground at a depth of 300 meters water equivalent. We will present results of radiopurity measurements of various samples studied, including modern steel samples and older steel samples thought to have been produced prior to World War 2 and the start of the nuclear age. [Preview Abstract] |
|
QA.00011: Monitor Detector for Relative Normalization with $^{\mathrm{6}}$He-CRES Experiment Regan Zite The $^{\mathrm{6}}$He Cyclotron Radiation Emission Spectroscopy (CRES) experiment at the University of Washington aims to precisely measure the Fierz coefficient by analyzing the cyclotron radiation of beta-decay electrons in a magnetic trap. This experiment takes data over a finite bandwidth which does not cover the entire beta spectrum. In order to \textit{stitch together} each piece of the spectrum, we use a silicon beta detector. We are testing the stability of a Passivated Implanted Planar Silicon (PIPS) detector and digitizer to be used to monitor beta activity. Initial tests were done with an $^{\mathrm{241}}$Am alpha source, cooled to -10 C to optimize resolution. With this system, we've achieved stability on the level of 10$^{\mathrm{-4}}$ as shown via an Allan deviation analysis. Our next measurements will be taken with a $^{\mathrm{90}}$Sr beta source whose energy spectrum more closely resembles that of $^{\mathrm{6}}$He. [Preview Abstract] |
|
QA.00012: Liquid Deuterium Thermosyphon for an Ultracold Neutron Source Kiera Augusto The TUCAN (TRIUMF Ultracold Advanced Neutron) EDM experiment seeks to measure the neutron electric dipole moment (EDM) with an uncertainty $\delta d_n=10^{-27}~e$cm. A new spallation-driven He-II ultracold neutron (UCN) source is developed at TRIUMF so that the goal statistical uncertainty can be reached. In the final layer of neutron moderation prior to UCN production, a liquid deuterium (LD$_2$) volume surrounds the He-II to efficiently moderate hotter spallation neutrons to the desired CN energies. The LD$_2$ moderator experiences a heat load of 60~W for the design proton beam current of 40~$\mu$A, and is cooled to 20~K using a distant cryocooler at higher elevation. This poster describes studies of the engineering design and performance of a natural circulation system (thermosyphon) used to provide cooling to the LD$_2$ volume near the hot spallation target. The thermosyphon features no moving parts and single-phase (liquid) operation. A key discovery made through these studies is that the thermosyphon will continue to flow despite the duty cycle from proton beam pulsing at minute-long timescales. [Preview Abstract] |
|
QA.00013: Preparing the HCal for the Forward Calorimeter System (FCS) Upgrade at STAR Anand Agrawal, William Bakke, Michael Bukowski, Claire Kovarik, Joseph (J.D.) Snaidauf The Solenoidal Tracker at RHIC (STAR) detector based at Brookhaven National Laboratory uses collisions of polarized protons to study QCD processes. The forward region of the detector, 2.5$<$$\eta$$<$4, is undergoing an upgrade to improve particle tracking and calorimetry. The new Forward Calorimeter System (FCS) will provide both hadronic (HCal) and electromagnetic (ECal) calorimetry that will support various physics programs. Di-jet reconstruction in this region of the detector will be possible and will provide insight into the gluon spin contribution, $\Delta$G. The FCS consists of a refurbished PHENIX sampling ECal and a newly constructed HCal, which will be a sandwich steel scintillator plate configuration. Both calorimeters will share the same cost-effective readout electronics, with SiPMs as photo-sensors. Fabrication of the 18,720 scintillation tiles for the HCal involves polishing of the two long edges, detailed painting to the two shorter edges, and preparation for shipping to STAR. Several institutions worked complementarily on the effort. This presentation will describe the work done by the authors at Valparaiso this summer as they spent part of their time each day to complete the preparation of 9,600 of these scintillation tiles, including the attendant QA. [Preview Abstract] |
|
QA.00014: Determining $\pi^0$ $A_{LL}$ from STAR 2012 Endcap Calorimeter Data Claire Kovarik, Anand Agrawal, Michael Bukowski, Joseph (JD) Snaidauf, William Bakke The Solenoidal Tracker at RHIC (STAR) located at Brookhaven National Laboratory uses longitudinally polarized proton-proton collisions to study the gluon contribution to the spin of the proton. One such method, using data from the 2012 longitudinally polarized proton-proton collisions ( $\sqrt{s}$ = 510 GeV), studies the production of neutral pions ( $\pi^0$ ) from these collisions. The asymmetry of the spin-dependent neutral pion production, $A_{LL}$, can be determined by analyzing the photons produced from $\pi^0$ decays, as detected in the Endcap Electromagnetic Calorimeter (EEMC). The EEMC, positioned in an intermediate pseudorapidity range of 1 $<$ $\eta$ $<$ 2, is able to measure the energy and position of an incoming photon’s electromagnetic shower. From these measurements the two-photon invariant mass spectrum can be reconstructed. These spectra are then fitted using a skewed Gaussian plus a background function to determine the total number of $\pi^0$ s. The $\pi^0$ asymmetry is calculated from the number of $\pi^0$ s produced in collisions of protons with different spin alignments. The status of the analysis of the 2012 data set to measure the $\pi^0$ $A_{LL}$ will be presented. [Preview Abstract] |
|
QA.00015: Abstract Withdrawn
|
|
QA.00016: Variance Extrapolation in an Oscillator Basis Isabella M. Zane, Mark A. Caprio, Patrick J. Fasano, Calvin W. Johnson The nuclear many-body problem is a challenging infinite-dimensional problem, for which only approximate results can be obtained. The solution can be approximated by solving the problem in a truncated, finite basis. However, the accuracy is limited by the largest basis accessible to current computational methods. Extrapolation techniques attempt to use results from calculations in smaller spaces to estimate the result which would be obtained from a calculation in a larger space. Extrapolation based on the energy variance of approximate eigenstates has been successfully applied in condensed matter physics and the nuclear Monte Carlo shell model. Here, we investigate the applicability of variance extrapolation to the no-core shell model (NCSM), a method for solving the nuclear many-body problem in a basis of oscillator functions. To explore the properties of variance extrapolation in an oscillator basis, we first consider a simpler one-dimensional problem. We then extend the variance extrapolation approach to NCSM calculations for light nuclei. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700