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 FH: Nuclear Reactions : Light Ions I |
Hide Abstracts |
Chair: Tomotsugu Wakasa, Kyushu University Room: Hilton Kona 2/3 |
Friday, October 26, 2018 9:00AM - 9:15AM |
FH.00001: 12C(n, 2n)11C cross section from threshold to 26.5 MeV Mark Yuly, Thomas Eckert, Garrett Hartshaw, Stephen J. Padalino, Danae N. Polsin, Megan Russ, Angela T. Simone, Carl R. Brune, Thomas Massey, Cody E. Parker, Ryan Fitzgerald, Thomas C. Sangster, Sean Regan The 12C(n,2n)11C cross section was measured from just below threshold to 26.5 MeV using the Pelletron accelerator at Ohio University. Monoenergetic neutrons, produced via the 3H(d,n)4He reaction, were allowed to strike targets of polyethylene and graphite. Activation of both targets was measured by counting positron annihilations resulting from the β+ decay of 11C. Annihilation gamma rays were detected, both in coincidence and singly, using back-to-back NaI detectors. The incident neutron flux was determined indirectly via 1H(n,p) protons elastically scattered from the polyethylene target. Previous measurements fall into upper and lower bands; the results of the present measurement are consistent with the upper band. |
Friday, October 26, 2018 9:15AM - 9:30AM |
FH.00002: Direct $^{157}$Gd($^3$He,$\alpha$2n)$^{154}$Gd reaction as a surrogate for $^{155}$Gd(n,2n)$^{154}$Gd Amanda M Lewis, Darren L Bleuel, Lee Allen Bernstein, Eric F Matthews, Tyler Nagel, Larry Eugene Ahle, Jason T Burke, Jennifer A Church, Roderick M Clark, James Elliot, Paul Fallon, Julian Gibelin, Bethany L. Goldblum, I-Yang Lee, Augusto O Macchiavelli, Margaret Anne McMahan, Larry William Phair, Eric B Norman, Elena Rodriguez-Vietez, Mathis Wiedeking Recent work on the surrogate reaction method has shown that accurate neutron capture cross sections can be obtained with the right corrections to the angular momentum distribution in the compound nucleus. Many surrogate experiments use transfer reactions, which can bring more angular momentum than neutron absorption. This can be corrected for, and in this work the experiment was set up to correct for the difference by decreasing the compound ($^3$He,$\alpha$) reactions. At the 88-inch Cyclotron at Lawrence Berkeley National Laboratory, $^{155}$Gd(n,2n) was studied using the surrogate reaction $^{157}$Gd($^3$He,$\alpha$2n). The STARS-LiBerAce detector system was used to detect forward-angle alphas and gammas de-exciting the $^{154}$Gd nuclei produced by the $^{157}$Gd($^3$He,$\alpha$2n) reaction. Coincidences between the alphas and gammas were used to determine the probability of the excited $^{154}$Gd nucleus decaying to $^{156}$Gd. The optical model was used to calculate the total neutron cross section of $^{155}$Gd, and the probability of decay to $^{154}$Gd was converted into a $^{155}$Gd(n,2n) cross section, which compared favorably to a measurement between 6 and 14 MeV. |
Friday, October 26, 2018 9:30AM - 9:45AM |
FH.00003: Deducing 155Gd(n,xn) cross sections using the surrogate method. R. O. Hughes, J. T. Burke, B. A. Alan, V. S. Kolhinen, H. I. Park, C. S. Reingold, A. Saastamoinen, B. Schroeder Neutron induced cross sections for unstable nuclei are essential to constrain models in Nuclear Astrophysics and also in applications such as reactor design/safety and Stockpile Stewardship. The surrogate method is an indirect technique that uses a charged particle reaction to populate the same Compound Nucleus as the neutron induced reaction and the cross section is subsequently deduced. The technique has been successfully applied for σ(n,f) and more recently σ(n,γ) but for (n,n') and (n,2n) cross sections, the surrogate method is unproven. An experiment was performed with the newly commissioned NeutronSTARS array comprising a silicon telescope (STARS) and high-efficiency, large volume liquid scintillator detector (Neutron Ball). The 156Gd(α,α'xn) reaction with 54MeV α's was used as a surrogate for 155Gd(n,xn) in order to deduce the (n,n') and (n,2) exit channel cross sections across a large equivalent neutron energy range. Results will be discussed. |
Friday, October 26, 2018 9:45AM - 10:00AM |
FH.00004: Prompt and delayed fission gamma rays from 235U(n,f) Gencho Rusev, Marian Jandel, John O'Donnell, Todd Bredeweg, Evelyn Bond, Aaron J Couture, Christopher J Prokop, Ionel Stetcu, Patrick Talou, John Ullmann A measurement of the prompt fission gamma rays from the 235U(n,f) reaction has been performed at LANSCE with the 4π BaF2 gamma-ray array DANCE. A thick 235U target was used in the experiment. The neutron detector, NEUANCE, provided the fission trigger by measuring the prompt fission neutrons. We will report results for the gamma-ray energy spectra and gamma-ray multiplicity disctributions from the prompt and delayed fission gamma rays from 235U(n,f). The experimental results are compared with predictions from the CGMF code. |
Friday, October 26, 2018 10:00AM - 10:15AM |
FH.00005: Investigation of neutron-induced ternary fission of U-238 and U-235 with the NIFFTE time projection chamber Jennifer Klay, Alex Kemnitz, Gabriel Oman Ternary fission is a rare process in which a nucleus breaks up into three daughters rather than two. The most common outcome is two heavier fragments accompanied by an alpha particle, with the upper limit for the third daughter set by tri-partition of the nucleus into three nearly equal mass fragments. Tracked fission event data recorded by the NIFFTE collaboration for neutron-induced fission of U-238 and U-235 targets have been analyzed to determine average opening angles, fragment energies, and production rates as a function of neutron energy for ternary candidates. Preliminary results from these studies will be presented. |
Friday, October 26, 2018 10:15AM - 10:30AM |
FH.00006: Evaluation of the Total Kinetic Energy of the Fission Fragments as a function of Incident-Neutron Energy Cameron Russell Bates, John Paul Lestone Predictions for the incident-neutron energy dependence of the total kinetic energy (TKE) release in the 239Pu(n,f) and 235U(n,f) reactions beyond the threshold of second-chance fission have been confirmed by recent experiments at Los Alamos. An evaluation of the measured energy dependence of the post-neutron emission average TKEs for the three target isotopes 235,238U and 239Pu has been performed, and incorporated into ENDF/B-VIII.0. |
Friday, October 26, 2018 10:30AM - 10:45AM |
FH.00007: Evidence of non-statistical properties in the $^{35}$Cl(n,p)$^{35}$S cross section J. C. Batchelder, S. A. Chong, J. T Morrell, M. Unzueta, P. Adams, J. D. Bauer, T. A. Bailey, Tim Becker, Lee Allen Bernstein, Massimiliano Frantoni, A. M. Hurst, J. James, E. F. Matthews, M. Negas, Daniel Rutte, K. Song, M. Wallace, K. Van Bibber, C. S. Waltz, A. M. Lewis The $^{35}$Cl(n,p)$^{35}$S and $^{35}$Cl(n,$\alpha$)$^{32}$P cross sections at incident neutron energies between 2.42 - 2.74 MeV, were measured using the Berkeley High Flux Neutron Generator (HFNG). $^{35}$Cl(n,$\alpha$) cross sections were consistant with the neutron capture data libraries. The cross sections for $^{35}$Cl(n,p) however, were more than a factor of three to five less than all of the values in the data libraries. The measured energy-differential cross section in this reaction is consistent with a single resonance with a width of 257(27)~keV. This result suggests that, despite the high incident neutron energy, any attempt to model (n,x) cross sections in the vicinity of the N = Z = 20 shell gap requires a resolved resonance approach rather than a Hauser-Fesbach. Future studies by our group will be presented and discussed. |
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