Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session CB: Applications of Nuclear Physics |
Hide Abstracts |
Chair: Christopher Morris, Los Alamos National Laboratory Room: Plaza II |
Thursday, October 25, 2012 8:30AM - 8:42AM |
CB.00001: Measuring the Ionization Yield of Low-Energy Nuclear Recoils in Liquid Argon Tenzing Joshi, Adam Bernstein, Jonathon Coleman, Michael Foxe, Chris Hagmann, Timothy Gushue, Igor Jovanovic, Kareem Kazkaz, Kostas Mavrokoridis, Vladimir Mozin, Eric Norman, Sergey Pereverzev, Samuele Sangiorgio, Peter Sorensen Liquid argon (LAr) has been proposed as a candidate target medium for the detection of coherent neutrino-nucleus scatter (CNNS). Design and deployment of a large ($\sim$10 kg active mass) dual-phase argon detector for the detection of CNNS at a nuclear power plant requires an understanding of the response of LAr to nuclear recoils from 0--6 keV. In this regime the prompt scintillation (S1) signal is below threshold and detection must rely solely on the ionization signal (S2) of the nuclear recoil. We briefly discuss the design and performance of a small prototype dual-phase argon detector and its calibration using $^{37}$Ar. We then report on our measurement of the ionization yield of nuclear recoils below 7 keV using this prototype detector with a filtered near-threshold $^7$Li(p,n) reaction as a neutron source. [Preview Abstract] |
Thursday, October 25, 2012 8:42AM - 8:54AM |
CB.00002: Beta-delayed neutron spectroscopy with trapped ions N.D. Scielzo, S. Padgett, M. Pedretti, R.M. Yee, E.B. Norman, P.F. Bertone, J.A. Clark, J.P. Greene, A. Perez Galvan, A.F. Levand, B.J. Zabransky, S.A. Caldwell, G. Savard, M.G. Sternberg, J. Van Schelt, D. Lascar, R.E. Segel, F. Buchinger, S. Gulick, G. Li, C.M. Deibel, K.S. Sharma Neutrons emitted following the beta decay of fission fragments play an important role in many fields of basic and applied science such as nuclear energy, nuclear astrophysics, and stockpile stewardship. Radioactive ions held in an ion trap are an appealing source of activity for improved studies of this decay process. When a radioactive ion decays in the trap, the recoiling daughter nucleus and emitted radiation emerge from the $\sim $1 mm$^{3}$ trap volume and propagate through vacuum with negligible scattering. For the first time, beta-delayed neutron spectroscopy is being performed by identifying neutron emission from the large nuclear recoil it imparts and using this recoil energy to reconstruct the neutron branching ratios and energy spectra. Results from a recent proof-of-principle measurement and plans for future experiments at Argonne National Laboratory using significantly higher intensity fission-fragment beams will be presented. [Preview Abstract] |
Thursday, October 25, 2012 8:54AM - 9:06AM |
CB.00003: Noninvasive Online Measurement of Genome Lengths of Mammalian Tissues in Bulk by 14 MeV Neutron Atometry Bogdan Maglich, Anna Radovic, Christian Druey Genome length, L=, no. of DNA nucleotide base pairs in cell of bovine (b) and porcine (p) tissues, closest to human genome, were hitherto measured by \textit{genomic} \textit{sequencing} L$_{b}$=3, L$_{p}$=2.7 Giga base pairs [1,2] (Gbp) errors not given. - We report measurements of L$_{b}$/L$_{p}$ and L$_{b,}$ L$_{p}$ \textit{without} sequencing by \textit{atometry} [3,4]. No. of O and C atoms, N, in nucleotide molecules, was obtained from prompt $\gamma $ rate, G, emitted in inel. scatt. 14 MeV neutrons, with nuclei of C, O, in nucleotide molecule. Since G prop. N, L$_{b}$/L$_{p}$=G$_{b}$/G$_{p. }$ p and b meat was irradiated for 30'. From msd G we obtained L$_{b }$/L$_{p}$=1.28$\pm $0.02 16{\%} greater than [1,2]. We got absolute L$_{b}$=1.65/f, L$_{p}$=1.28/f Gbp, 0.3$<$f$<$0.6 by irradiating 3 DNA's and calibrating $\gamma $/O and $\gamma $/C. \\[4pt] [1] Y.Liu et al: Bos Taurus genome assembly; BMC Genomics 2009, 10:180\\[0pt] [2] L.B. Schook et al, Swine Genome Sequencing: Comparative and Functional genomics, V. 6, Issue 4, 251, June 2005\\[0pt] [3] Maglich B. et al, http://whitehousedrugpolicy.gov/ctac99/pdfs/kani.pdf\\[0pt] [4] Maglich B.C. AIP Conf. Proc. 796,431(2005); http://link.aip.org/link/?APCPCS/796/431/1 [Preview Abstract] |
Thursday, October 25, 2012 9:06AM - 9:18AM |
CB.00004: Validation of (n,$\gamma$) Surrogate Reactions: $^{95}$Mo(d,p$\gamma$) Studies A. Ratkiewicz, J.A. Cizewski, S. Burcher, M.E. Howard, B. Manning, S. Rice, C. Shand, J.T. Burke, R.J. Casperson, N. Scielzo, R.A.E. Austin, R.O. Hughes, T.J. Ross, M. McClesky, W.A. Peters The importance of neutron capture on exotic nuclei to nucleosynthesis and applications of nuclear physics has been the subject of much recent discussion. Due to the difficulty of performing direct measurements of the (n,$\gamma$) reaction with exotic nuclei, the (d,p$\gamma$) reaction was proposed as a surrogate reaction for (n,$\gamma$). The (d,p$\gamma$) reaction at low energies is a promising surrogate for neutron capture, as both reactions transfer relatively little angular momentum to the system. We have initiated a campaign to validate (d,p$\gamma$) as a surrogate for neutron capture using $^{95}$Mo as a target and measuring the intensity of transitions from states in $^{96}$Mo populated in the $^{95}$Mo(d,p$\gamma$) reaction. We present preliminary results from measurements conducted with the STARLiTe detector system at TAMU and discuss the status of the program to validate the (d,p$\gamma$) reaction in normal and inverse kinematics as a surrogate for neutron capture. \noindent This work is supported in part by the U.S. D.O.E. [Preview Abstract] |
Thursday, October 25, 2012 9:18AM - 9:30AM |
CB.00005: Validation of (n,gamma) surrogate methods and the 95Mo(n,gamma) reaction J.A. Cizewski, A.S. Adekola, M.E. Howard, B. Manning, A. Ratkiewicz, A.J. Couture, M. Devlin, N. Fotiades, R.O. Nelson, J.M. O'Donnell, W.A. Peters, J.T. Burke, J.E. Escher, R. Hatarik, N.D. Scielzo Neutron capture on unstable isotopes is important for the synthesis of heavy elements through both the r and s processes and so for nuclear energy and stockpile stewardship science. However, it is difficult to measure these cross sections directly with neutrons on targets that live less than about 100 days. Therefore, there has been a concerted effort by many groups [J.E. Escher RMP 84, 353 (2012) and references therein] to develop a validated surrogate reaction for neutron capture, a reaction that predominantly occurs at relatively low neutron energies where the angular momentum dependence needs to be taken into account. Many of the surrogate approaches use partial cross sections of discrete low-lying gamma-ray transitions to deduce the decay of the compound nucleus. Yet there have been very few measurements of the intensity of these discrete transitions in (n,g) as a function of neutron energy up to 200 keV. As part of the program to validate (d,pg) as a surrogate for neutron capture, we have recently measured the intensity of yrast transitions in 96Mo populated by the 95Mo(n,g) reaction with a small array of HPGe detectors on FP12 at the Lujan Center of LANSCE. Preliminary results of these measurements and the status of the (d,pg) validation program with 95Mo targets will be presented. [Preview Abstract] |
Thursday, October 25, 2012 9:30AM - 9:42AM |
CB.00006: Neutron Capture Cross Section of $^{239}$Pu S. Mosby, C. Arnold, T.A. Bredeweg, A. Chyzh, A. Couture, J.M. Gostic, R.A. Henderson, M. Jandel, E. Kwan, J.M. O'Donnell, G. Rusev, J.L. Ullmann, C-Y. Wu The $^{239}$Pu(n,$\gamma$) cross section has been measured at the Los Alamos Neutron Science Center (LANSCE). The Detector for Advanced Neutron Capture Experiments (DANCE) provided a highly segmented 4$\pi$ measurement of the energy and multiplicity distributions for emitted $\gamma$-rays, while a PPAC detected coincidence fission fragments. The simultaneous measurement of (n,$\gamma$) and (n,f) events resulting from a single sample allowed the (n,$\gamma$) cross section to be measured as a ratio to fission with reduced systematic uncertainty. Results from the current analysis will be presented. [Preview Abstract] |
Thursday, October 25, 2012 9:42AM - 9:54AM |
CB.00007: ABSTRACT WITHDRAWN |
Thursday, October 25, 2012 9:54AM - 10:06AM |
CB.00008: Improved Capture Gamma-Ray Libraries for Nuclear Applications Brad Sleaford, Richard Firestone, Neil Summers, Jutta Escher The neutron capture reaction is of fundamental use in identifying and analyzing the gamma-ray spectrum from an unknown object as it gives unambiguous information on which isotopes are absorbing the neutrons. There are known data gaps in the ENDF libraries used by transport codes which are critical to various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes. This database is used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the unresolved quasi continuum part of the gamma cascades are not experimentally available. This continuum can contain up to 90{\%} of all the decay energy, in this work it is modeled with the statistical nuclear structure code Dicebox. We plan to continue the Dicebox approach through the resolved resonance region where spin and parity information is partially known. At higher energies to 20 MeV we are applying Hauser Feshbach models to predict the cross sections of gamma spectra to improve the neutron data libraries used for transport modeling of unknown objects. [Preview Abstract] |
Thursday, October 25, 2012 10:06AM - 10:18AM |
CB.00009: Nuclear Energy and Synthetic Liquid Transportation Fuels Richard McDonald This talk will propose a plan to combine nuclear reactors with the Fischer-Tropsch (F-T) process to produce synthetic carbon-neutral liquid transportation fuels from sea water. These fuels can be formed from the hydrogen and carbon dioxide in sea water and will burn to water and carbon dioxide in a cycle powered by nuclear reactors. The F-T process was developed nearly 100 years ago as a method of synthesizing liquid fuels from coal. This process presently provides commercial liquid fuels in South Africa, Malaysia, and Qatar, mainly using natural gas as a feedstock. Nuclear energy can be used to separate water into hydrogen and oxygen as well as to extract carbon dioxide from sea water using ion exchange technology. The carbon dioxide and hydrogen react to form synthesis gas, the mixture needed at the beginning of the F-T process. Following further refining, the products, typically diesel and Jet-A, can use existing infrastructure and can power conventional engines with little or no modification. We can then use these carbon-neutral liquid fuels conveniently long into the future with few adverse environmental impacts. [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