Bulletin of the American Physical Society
2019 Fall Meeting of the APS Division of Nuclear Physics
Volume 64, Number 12
Monday–Thursday, October 14–17, 2019; Crystal City, Virginia
Session SK: Applications of Nuclear Physics |
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Chair: Andrew Rogers, University of Massachusetts, Lowell Room: Salon F/G |
Thursday, October 17, 2019 10:30AM - 10:42AM |
SK.00001: Sensitivity of FREYA to model inputs in simulations of 252Cf(sf) Ramona Vogt, Jorgen Randrup, Patrick Talou Employing the complete fission event generator $\mathtt{FREYA}$, we study the sensitivity of neutron observables to the input yield function $Y (A, Z, {\rm TKE})$ [1]. We first perform a statistical analysis of the available fission data to determine the distribution of possible yield functions and construct an ensemble of 15,000 such yield functions. For each of these, $\mathtt{FREYA}$ is used to generate one million fission events, leading to a corresponding ensemble of fission observables, including the neutron multiplicity distribution and its factorial moments, the neutron energy spectrum, and the neutron-neutron angular correlation. Thus we can study the sensitivity of those neutron observables to the uncertainty in the input yields. Particular attention is given to the anti-correlation between the mean neutron multiplicity $\overline \nu$ and the mean total fragment kinetic energy TKE. Because $\overline \nu$ is very well determined, we employ this anti-correlation to derive a significantly stricter tolerance on TKE. We also study the sensitivity to the $\mathtt{FREYA}$ input parameters.\par \noindent [1] J. Randrup, P. Talou and R. Vogt, Phys. Rev. C {\bf 99}, 054619 (2019). [Preview Abstract] |
Thursday, October 17, 2019 10:42AM - 10:54AM |
SK.00002: Development of $^{\mathrm{129}}$I AMS at the Nuclear Science Laboratory for Sampling in the Great Lakes Region Michael Skulski, Tyler Anderson, Lauren Callahan, Adam Clark, Austin Nelson, Philippe Collon, Michael Paul $^{\mathrm{129}}$I in the environment primarily comes from its release from nuclear fuel reprocessing centers in Europe. Iodine moves through the environment very easily as it is highly soluble and easily incorporated into biological organisms. This high mobility makes $^{\mathrm{129}}$I an excellent environmental tracer in a variety of fields including geology, nuclear forensics, and nuclear safeguards. However, because of its long half-life of 15.7 Myr, detection of $^{\mathrm{129}}$I through direct decay counting methods is often unachievable because of the sample size that would be required. Accelerator mass spectrometry (AMS), on the other hand, is well suited to the detection of $^{\mathrm{129}}$I as it can identify individual ions through isotopic and isobaric discrimination. The environmental sampling throughout the United States has been primarily limited to the areas surrounding nuclear facilities, but there are few measurements of the concentrations of $^{\mathrm{129}}$I throughout the rest of the country. This has inspired the AMS group of the Nuclear Science Laboratory at the University of Notre Dame to measure the concentrations in the Great Lakes region to establish a baseline for measuring the change of these concentrations in the future. Preliminary results of $^{\mathrm{129}}$I measurements and future plans will be discussed. [Preview Abstract] |
Thursday, October 17, 2019 10:54AM - 11:06AM |
SK.00003: In-Situ Beam Current Monitoring Reaction for in-air Particle-Induced Gamma Emission Spectroscopy John Wilkinson Particle-induced gamma emission spectroscopy performed in-air takes advantage of the nuclear monitoring reaction of 40Ar(p,n$\gamma )$40K for beam current normalization. The second excited state of 40K deexcites with characteristic gamma line 770 keV and is easily observed using the same HPGe detector as for sample analysis. Experimentation has been conducted at the University of Notre Dame's Nuclear Structure Laboratory using 4 MeV protons impinged on targets of interest using a modified Alphatross ion source with a 3 MV 9S tandem accelerator. Preliminary data shows this technique has reduced analysis uncertainty and simultaneously tracks both beam intensity and optics over several hours. [Preview Abstract] |
Thursday, October 17, 2019 11:06AM - 11:18AM |
SK.00004: Nuclear Physics and Planetary Exploration Katherine Mesick, Daniel Coupland, Kurtis Bartlett Neutron and gamma-ray spectroscopy (NGRS) of planetary bodies has become a standard technique for measuring distinctive geochemical compositions and volatile abundance signatures for key elements relevant to planetary structure and evolution. These measurements also provide important information for in-situ resource utilization and human exploration. On airless or near-airless bodies, Galactic Cosmic Rays (GCRs) interact within the top meter of planetary surfaces, producing spallation neutrons. Moderation of GCR spallation neutrons by hydrogen provides a unique signature indicating the presence and abundance of near-surface water. These neutrons also undergo inelastic scattering or capture with the surrounding material, resulting in gamma-ray emission at distinct energies. Neutron and gamma-ray detectors onboard orbiting spacecraft or landed rovers detect the leakage neutron and gamma-ray signatures and require good gamma-ray energy resolution, neutron energy determination over twelve orders of magnitude, and operation in harsh environments under mission resource constraints. This talk will describe NGRS basics and the Elpasolite Planetary Ice and Composition Spectrometer under development at LANL for next-generation, low-resource planetary science missions. [Preview Abstract] |
Thursday, October 17, 2019 11:18AM - 11:30AM |
SK.00005: Updated Sensitivities for Accelerator Mass Spectrometry at the Notre Dame Nuclear Science Laboratory Adam Clark, Tyler Anderson, Lauren Callahan, Austin Nelson, Michael Skulski, Philippe Collon Accelerator Mass Spectrometry (AMS) is an ultra-sensitive measuring technique excelling for long-lived isotopes where direct decay counting becomes impractical. At the University of Notre Dame's Nuclear Science Laboratory (NSL), AMS capabilities for a select few isotopes have been developed over the last decade for studies ranging from radiocarbon dating ($^{\mathrm{14}}$C), to nuclear astrophysics ($^{\mathrm{36}}$Cl, $^{\mathrm{41}}$Ca,$^{\mathrm{\thinspace 44}}$Ti, $^{\mathrm{60}}$Fe, $^{\mathrm{93}}$Zr), and nuclear forensics ($^{\mathrm{129}}$I). However, limitations and shortcomings in the accelerator system were identified. This prompted upgrades and modifications to both the low energy injection to the accelerator system and to the AMS beamline. The current status of the accelerator system and its recent improvements will be presented along with updated measurement sensitivities and developments toward measuring new isotopes at the NSL. This work is supported by the NSF: PHY-1713857 (NSL) and PHY-1337608 (MRI) [Preview Abstract] |
Thursday, October 17, 2019 11:30AM - 11:42AM |
SK.00006: Further Development of $^{\mathrm{41}}$Ca for Production Cross Section Measurements Austin Nelson, Tyler Anderson, Lauren Callahan, Adam Clark, Michael Skulski, Philippe Collon Short Lived Radionuclides (SLRs), or isotopes with half-lives that are short compared to the age of the Solar System, are integral to understanding the formation of the Solar System. Evidence from SLR concentrations in meteorites can help determine Solar System production sources, but there are still debates on specific production mechanisms and their underlying processes. The X-wind model attempts to explain observed SLR abundances through the use of protosolar cosmic-ray irradiation and relies on theoretical calculations for a wide range of nuclear reactions needed for isotopic production models. $^{\mathrm{41}}$Ca (t$_{\mathrm{1/2}} \quad =$ 9.94 x 10$^{\mathrm{4}}$ yrs) is an important SLR and it's production in the early Solar System can help determine the viability of models of early stellar processes. Information on the production of $^{\mathrm{41}}$Ca is limited and several production cross sections have minimal or no experimental data. $^{\mathrm{41}}$Ca detection capabilities have recently been developed at the University of Notre Dame's Nuclear Science Laboratory (NSL) utilizing the technique of accelerator mass spectrometry (AMS). Recent upgrades to the AMS beamline have been made, so new sensitivity limits will be discussed along with first $^{\mathrm{41}}$Ca production activations for future cross-section measurements. [Preview Abstract] |
Thursday, October 17, 2019 11:42AM - 11:54AM |
SK.00007: Development of a University Molten Salt Research and Test Reactor Rusty Towell Nuclear fission is a tremendous energy source that remains underutilized globally to address the need for abundant, safe, carbon-free energy on demand. This regrettable situation can be rectified with the development of advanced reactors that are capable of meeting the world's energy needs without the risk of proliferation. To address this challenge, the Nuclear Energy eXperimental Testing (NEXT) Lab has been launched at Abilene Christian University. The NEXT Lab mission is to provide global solutions to the world's needs for energy that is less expensive and safer, water that is pure and abundant, and medical isotopes used to diagnose and treat cancer by advancing the technology of molten salt reactors while educating the next generation of leaders in nuclear science and engineering. The NEXT Collaboration is focusing on advancing the technical readiness level of molten salt as a coolant in liquid fueled molten salt reactors. Along with our university consortium, we are developing a plan to construct the first university molten salt research and test reactor. The current status of NEXT will be presented including the breath of research across many disciplines and our timeline for the construction of a research reactor. [Preview Abstract] |
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