Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session PJ: Applications of Nuclear Physics II |
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Chair: Sean Kuvin, LANL Room: Tremont |
Thursday, October 14, 2021 9:30AM - 9:42AM |
PJ.00001: Development and Fielding of a Spectrometer for High Flux CW/Pulsed Neutron Beam Characterization Christopher Brand, Darren L Bleuel, Lee A Bernstein, Brian Rusnak, Marsh A Roark, Bethany L Goldblum, Josh Brown, Joseph Gorden, Thibault A Laplace, Jon C Batchelder Fast, high-flux neutrons are an attractive source for imaging due to their ability to penetrate high-Z materials. Intense neutron sources also provide a powerful tool to measure neutron scattering cross sections needed to advance basic and applied nuclear science and engineering. However, intense continuous neutron sources are difficult to characterize due to the inapplicability of traditional time-of-flight techniques and detection challenges associated with high count rates. A novel neutron diagnostic system for use at an advanced fast neutron imaging facility is being developed at Lawrence Livermore National Laboratory (LLNL). This scatter time-of-flight (sTOF ) neutron spectrometer will: (1) have high energy resolution for fast neutrons; (2) be compatible with both low current, pulsed neutron sources and high current, continuous neutron beams; and (3) function in a high radiation background environment. A successful first test of the sTOF spectrometer was conducted at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory using neutrons produced from a 14 MeV deuteron beam incident on a 3.7-mm-thick carbon target. These results were compared to literature data as well as neutron foil activation analysis results. |
Thursday, October 14, 2021 9:42AM - 9:54AM |
PJ.00002: Abstract Withdrawn
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Thursday, October 14, 2021 9:54AM - 10:06AM |
PJ.00003: Design and Simulation of a Next-Generation Dual n-gamma Detector Array at Los Alamos National Laboratory Eames A Bennett, Keegan J Kelly, Matthew J Devlin, John M O'Donnell Measurements of neutron elastic and inelastic scattering remain one of the largest uncertainties in simulations of fission-driven nuclear systems. Current experimental techniques are limited by issues arising from measuring only neutrons or gammas or, in the case where both particles are measured, the relatively small number of angles current dual n-gamma detectors are capable of covering. Next-generation elpasolite detectors offer near-perfect n-gamma pulse shape discrimination across a wide array of energies and the availability of these detectors in sufficient quantities make the construction of a large, highly-segmented detector array a possibility for the first time. Preliminary studies have isolated CLYC detectors as the ideal candidate for use in measuring neutron elastic scattering. We describe the mechanical design and simulation of the next-generation dual n-gamma detector array utilizing these detectors currently under development at Los Alamos National Laboratory. Additionally, we discuss an ongoing experimental campaign utilizing CLYC detectors in conjunction with Chi-Nu’s existing array of 54 liquid scintillator detectors to measure neutron scattering on 9Be and 56Fe. |
Thursday, October 14, 2021 10:06AM - 10:18AM |
PJ.00004: Cross section measurement of 114Cd(n,γ) reaction using the Detector for Advance Neutron Capture Experiments (DANCE). Kofi T Assumin-Gyimah, Benjamin Crider, Dipangkar Dutta, Timilehin H Ogunbeku, Durga P Siwakoti, Aaron J Couture, Cathleen E Fry, Christopher J Prokop, John L Ullmann, Stephanie Lyons The study of 114Cd nucleus cross section is important owing to its astrophysical applications and its presence in neutron absorption applications using natural Cd. The uncertainties in the cross section of 114Cd has been found by a recent sensitivity study to have a significant impact on the final s-process abundance uncertainties. Also, study of the 114Cd(n,γ)115Cd cross section is essential for improving the reliability of calculations investigating the nature of possible M1 strength in 114Cd and properties of nuclei far from stability. We will present preliminary result of 114Cd(n,γ) cross section measured with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. |
Thursday, October 14, 2021 10:18AM - 10:30AM |
PJ.00005: Precision Measurement of the Relative Gamma-Ray Intensities Following the Decay of 61Cu Darren L Bleuel, Lee A Bernstein, Roark A Marsh, Jonathan T Morrell, Andrew S Voyles A discrepancy, well outside reported uncertainties, has been observed between the accepted and measured intensity ratios of the two strongest gamma rays following 61Cu β decay. This discrepancy has significant impact since the natNi(d,x)61Cu reaction has historically been one of the few IAEA recommendations for use as a deuteron flux monitor. A considerable number of published cross sections measured in ratio to that beam monitor cross section may depend on the choice of using either the first or second strongest gamma ray in those calculations. To determine the magnitude of this error most precisely, over a hundred separate measurements of the 283 keV to 656 keV gamma-ray emission ratio were collected from seven experiments and a variety of detectors and detection geometries. A weighted average of these ratios indicates an 11% error in the value listed in the Nuclear Data Sheets, most probably in the second-highest intensity gamma ray, 656 keV. This has potentially introduced an 11% error in 61Cu production cross section measurements, cross sections using nickel activation as a deuteron beam current monitor, and/or in dose rates when 61Cu is used in nuclear medicine. |
Thursday, October 14, 2021 10:30AM - 10:42AM |
PJ.00006: 58,60Ni(n,Z) double-differential cross section measurements with LENZ at LANSCE Daniel Votaw, Brad BiGiovine, Anastasia Georgiadou, Sean A Kuvin, Lukas Zavorka, Hye Young Lee (n,Z) reaction cross sections on stable, structural materials at fast neutron energies are important for understanding H and He production in fusion and Gen IV fission reactors. But for certain reactions, or at certain energies, data are sparse, and evaluated cross sections disagree. Improved measurements of exclusive cross sections and angular distributions are needed to inform evaluations. During the 2019 run cycle at the Los Alamos Neutron Science CEnter (LANSCE) Weapons Neutron Research (WNR) facility, the Low-Energy N,Z (LENZ) setup was used to measure double-differential (neutron energy, charged particle angle) cross sections for (n,p) and (n,a) reactions on 58,60Ni, for neutron energies ranging from ~1 – 20 MeV. The results of this measurement will also inform the analysis of recent LENZ measurements on unstable isotopes 56,59Ni. Preliminary results for 58,60Ni will be presented. |
Thursday, October 14, 2021 10:42AM - 10:54AM |
PJ.00007: Fission of 205,207,209Bi Isotopes Using Proton-Bombardment of 204,206,208Pb Mark A Stoyer, Ben M Swinton-Bland, David J Hinde, Annette C Berriman, C. Simenel, J Buete, Kaushik Banerjee, Lauren Bezzina, Ian P Carter, Kaitlin J Cook, Mahananda Dasgupta, D Y Jeung, C Sengupta, Edward C Simpson, T Tanaka, Kirsten Vo-Phuoc Fission mass distributions for 205,207,209Bi nuclei at excitation energies close to their fission barriers were measured to determine how the mass distributions change with excitation energy and the neutron number of the compound nucleus1. Proton beams at various energies were delivered by the 14UD Tandem Electrostatic Accelerator at the Australian National University Heavy Ion Accelerator Facility. Fission fragments were measured using the CUBE fission spectrometer and fission fragment mass distributions were determined using a newly developed time difference analysis method. Measured mass distributions of all three Bi isotopes exhibit a component of mass-asymmetric fission at all energies studied. Comparisons between the three Bi isotopes at similar excitation energies hint at an increase in the mass-symmetric fission yield with increasing neutron number, which could be due to a decrease in the difference between the symmetric and asymmetric fission barriers. The probability of mass-asymmetric fission decreases significantly with increasing excitation energy, from ~ 70% to ~ 40% over a 10 MeV range. The mass distributions were compared with GEF2 and PES3 semiempirical models.
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Thursday, October 14, 2021 10:54AM - 11:06AM |
PJ.00008: The IsoDAR Experiment and Medical Applications of a High Power Cyclotron Loyd Waites, Janet M Conrad, Jose R Alonso, Daniel Winklener
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Thursday, October 14, 2021 11:06AM - 11:18AM |
PJ.00009: First steps on Neutron emission in the proton-induced fission of 238U Cristina Bordeanu
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