Bulletin of the American Physical Society
2017 Fall Meeting of the APS Division of Nuclear Physics
Volume 62, Number 11
Wednesday–Saturday, October 25–28, 2017; Pittsburgh, Pennsylvania
Session CB: Mini-Symposium on Direct Reactions as a Probe of Nuclear Structure and Nuclear Astrophysics-New Techniques and Instrumentation I |
Hide Abstracts |
Chair: Alan Wuosmaa, University of Connecticut Room: Salon 2 |
Thursday, October 26, 2017 8:30AM - 9:06AM |
CB.00001: Direct Reactions for Nuclear Astrophysics studies Invited Speaker: Sergio Almaraz-Calderon Direct reactions have long been considered attractive and powerful tools to study nuclear structure, nuclear reactions and nuclear astrophysics phenomena. Critical astrophysical reactions are often governed by short-lived nuclei away from stability. Great progress has been made with the development of radioactive beams. However, the direct measurement of some crucial astrophysical reactions is still unfeasible. Direct reactions are often an alternative method which allows to extract astrophysically relevant reaction rates by studying the structure of the nuclei involved. In this talk, I will review some recent efforts in experimental techniques using direct reactions to constraint astrophysical reaction rates. Results from a novel experiment to understand the destruction of Galactic $^{26}$Al via radiative proton captures on its isomeric 0$^+$ state will be presented. [Preview Abstract] |
Thursday, October 26, 2017 9:06AM - 9:18AM |
CB.00002: Precise Tests of Ab-initio Calculations of Light Nuclei and Charge Symmetry Breaking in A=10 $^{10}$B S. A. Kuvin, A. H. Wuosmaa, D. G. McNeel, C. J. Lister, C. Morse, M. L. Avila, C. R. Hoffman, B. P. Kay, R. B. Wiringa, E. A. McCutchan, A. A. Sonzogni, D. Santiago-Gonzalez, J. R. Winkelbauer Electromagnetic transition matrix elements have provided stringent tests of modern ab-initio calculations using realistic nuclear forces. Precise measurements of the B(E2:2$\rightarrow$0) transition rates in $\mathrm{^{10}B}$e and $\mathrm{^{10}}$C have been compared to recent Variational and Greens Function Monte Carlo calculations and the formulation of the 3-body forces [1,2]. They revealed that these electric transitions are almost purely isoscalar in character, corresponding to tumbling of the di-alpha core. Precise measurements of the analogous transition in $\mathrm{^{10}B}$ provide additional constraints for a possible isotensor contribution. The relevant state in $\mathrm{^{10}B}$, at E$_x$ = 5.164 MeV, is particle unbound. Therefore, precise measurements of both the particle decay branch and the gamma branch are needed to extract the electric transition rate. We report on a new study of the $\alpha$-particle branch by studying the $^{10}$B(p,p$'$)$^{10}$B* reaction in inverse kinematics with the HELIOS spectrometer at Argonne National Laboratory. [1] E.A. McCutchan et al., Phys.Rev.Lett. 103, 192501 (2009). [2] E.A. McCutchan et al., Phys.Rev. C 86 014312 (2012). [Preview Abstract] |
Thursday, October 26, 2017 9:18AM - 9:30AM |
CB.00003: Reaction Measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) Gas Jet Target K.A. Chipps The development of radioactive ion beams for reaction measurements was a major step forward in nuclear astrophysics, reactions, and structure. However, the move to inverse kinematics presented unique difficulties, in particular with regard to the targets used in such studies. Lower beam intensities may require thicker targets, but this negatively affects the experimental resolution and potential backgrounds. A recent development toward studies of nuclear reactions is the commissioning of the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target. The JENSA system provides a pure, homogeneous, highly localized, dense, and robust gaseous target for radioactive ion beam studies. Charged-particle reactions measurements made with gas jet targets can be cleaner and display better resolution than with traditional targets. With the availability of pure and localized gas jet targets in combination with developments in exotic radioactive ion beams and next-generation detector and spectrometer systems, the range of reaction studies that are experimentally possible is vastly expanded. This talk will focus on the benefits of performing reaction measurements with a gas jet target, including discussion of several example cases using JENSA. [Preview Abstract] |
Thursday, October 26, 2017 9:30AM - 9:42AM |
CB.00004: Direct Reactions at the Facility for Experiments on Nuclear Reactions in Stars (FENRIS) Richard Longland, John Kelley, Caleb Marshall, Federico Portillo, Kiana Setoodehnia Nuclear cross sections are a key ingredient in stellar models designed to understand how stars evolve. Determining these cross sections, therefore, is critical for obtaining reliable predictions from stellar models. While many charged-particle reaction cross sections can be measured in the laboratory, the Coulomb barrier means that they cannot always be measured at the low energies relevant to astrophysics. In other cases, radioactive targets make the measurements unfeasible. Radioactive ion beam experiments in inverse kinematics are one solution, but low beam intensities mean that cross sections plague these attempts further. Direct measurements, particularly particle transfer experiments, are one tool in our inventory that provides us with the necessary information to infer reaction cross sections at stellar energies. I will present an overview of one facility: the Facility for Experiments on Nuclear Reactions in Stars (FENRIS), which is dedicated to performing particle transfer measurements for astrophysical cross sections. Over the past few years, FENRIS has been fully upgraded and characterized. I will show highlights of our upgrade activities and current capabilities. I will also highlight our recent experimental results and discuss current upgrade efforts. [Preview Abstract] |
Thursday, October 26, 2017 9:42AM - 9:54AM |
CB.00005: Gamma Ray Spectroscopy of $^{\mathrm{19}}$Ne near the $^{\mathrm{18}}$F$+$p Threshold Matthew Hall, Daniel Bardayan A direct way to test nova explosion models would be to observe gamma rays created in the decay of radioactive isotopes produced in the nova. One such isotope, $^{\mathrm{18}}$F, is believed to be the main source of observable 511-keV gamma rays. The main destruction mechanism of $^{\mathrm{18}}$F is thought to be the $^{\mathrm{18}}$F(p,$\alpha )^{\mathrm{15}}$O reaction, and uncertainty in the reaction rate is attributed to uncertainties in the energies, spins, and parities of the nuclear levels in $^{\mathrm{19}}$Ne above the proton threshold. In an effort to understand these levels the $^{\mathrm{19}}$F($^{\mathrm{3}}$He,t)$^{\mathrm{19}}$Ne reaction was measured at Argonne National Laboratory using a $^{\mathrm{3}}$He beam. Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS) was used to measure gamma rays from the de-excitation of $^{\mathrm{19}}$Ne in coincidence with the reaction tritons. Preliminary data from the experiment will be presented. This work was supported in part by National Science Foundation and U.S. Department of Energy. [Preview Abstract] |
Thursday, October 26, 2017 9:54AM - 10:06AM |
CB.00006: Alpha-capture reaction rates for 22Ne(alpha,n) via sub-Coulomb alpha-transfer and its effect on final abundances of s-process isotopes Heshani Jayatissa, Grigory Rogachev, Yevgeny Koshchiy, Vladilen Goldberg, Joshua Hooker, Curtis Hunt, Cordero Magana, Brian Roeder, Antti Saastamoinen, Alexandria Spiridon, Sriteja Upadhyayula, Oscar Trippella The 22Ne($\alpha$,n) reaction is a very important neutron source reaction for the slow neutron capture process (s-process) in asymptotic giant branch stars. These direct measurements are very difficult to carry out at the energy regimes of interest for astrophysics (Gamow energies) due to the extremely small reaction cross section. The large uncertainties introduced when extrapolating direct measurements at high energies down to the Gamow energies can be overcome by measuring the Asymptotic Normalization Coefficients (ANC) of the relevant states using $\alpha$-transfer reactions at sub-Coulomb energies to reduce the optical model dependence. The study of the 22Ne(6Li,d) and 22Ne(7Li,t) reaction was carried out at the Cyclotron Institute at Texas A$\&$M University. The $\alpha$-ANC measurements for the near $\alpha$-threshold resonances of 26Mg provide constraints for the 22Ne($\alpha$,n) reaction rate. The effect of this reaction rate on the final abundances of the s-process isotopes will be discussed. [Preview Abstract] |
Thursday, October 26, 2017 10:06AM - 10:18AM |
CB.00007: Extracting Spectroscopic Factors of Argon Isotopes from Transfer Reactions Juan Manfredi, M.B. Tsang, W.G. Lynch, K.W. Brown, G. Cerizza, J. Barney, J. Estee, C. Loelius, S. Sweany, C. Anderson, H. Setiawan, J. Winkelbauer, K. Smith, J. Lee, Z. Xu, A. Rogers, C. Pruitt, Z. Chajecki, G. Chen, C. Langer, Z. Xiao, Z. Li, C. Niu A spectroscopic factor (SF) quantifies the single particle structure of a given state in a nucleus. There is a discrepancy in extracted SF's between studies that use transfer reactions and those that use knockout reactions. Resolving this discrepancy is important both for understanding reaction probes as well as constraining nuclear structure theory. Kinematically complete measurements of the transfer reactions $^{34}$Ar(p,d) and $^{46}$Ar(p,d) were performed at the National Superconducting Cyclotron Laboratory. The same beam energy (70 MeV/u) was used as in a previous knockout measurement to account for energy dependence in the relevant optical potentials. Preliminary results will be presented. In addition, findings from measurement of the two-neutron transfer reactions $^{34}$Ar(p,t) and ${^46}$Ar(p,t) will be discussed. [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