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 MB: Mini-Symposium: Particle Emission and Exotic Nuclei |
Hide Abstracts |
Chair: Andrew Rogers, University of Massachusetts, Lowell Room: Salon 2 |
Wednesday, October 16, 2019 2:00PM - 2:36PM |
MB.00001: Recent discoveries on particle emitting nuclei Invited Speaker: Kalle Auranen In this presentation I will provide a brief introduction to the concepts of particle emission from exotic nuclei. Measuring the energies of the emitted particles, ideally correlated to residue implantation event or subsequent decay events, provides a clean and precise probe to study the underlying nuclear structure and masses of the initial and final nuclei. Such correlations can also be used in experiments with very limited statistics, making it suitable for the identification of new elements and new isotopes. Particle emission studies are important in understanding of the structure of atomic nuclei, but they also serve an experimental probe to study the astrophysical processes, such as the \textit{r}- and \textit{rp} processes, occurring far away from the valley of $\beta$-stability. I will introduce these topics by summarizing a few of the recent highlights on particle emitting nuclei including, but not limited to, the discovery of ``superallowed" $\alpha$-decay chain $^{108}$Xe$\rightarrow^{104}$Te$\rightarrow^{100}$Sn [1], and a very weak proton emission branch in $^{108}$I [2]. The former is an important benchmark for the models of $\alpha$ decay, whereas the latter observation allowed us to study the termination of the astrophysical \textit{rp} process. \begin{enumerate} \itemsep=-5pt \bibitem{ref1} Phys. Rev. Lett. \textbf{121}, 182501 (2018) \bibitem{ref2} Phys. Lett. B \textbf{792}, 187 (2019) \end{enumerate} [Preview Abstract] |
Wednesday, October 16, 2019 2:36PM - 2:48PM |
MB.00002: Particle Decay of the 6.15 MeV Level in $^{18}$Ne K.A. Chipps, S.D. Pain, P. Thompson, R.L. Kozub The $^{14}$O($\alpha$,p)$^{17}$F reaction rate is important as a trigger reaction in x-ray bursts and has significant impact on the burst light curve and final abundances. In addition, the reaction provides a pathway to alter the ratio of $^{14}$O to $^{15}$O in the accreted material over time. A $J^{\pi} = 1^-$ resonance in $^{18}$Ne above the $^{14}$O+$\alpha$ threshold is expected to dominate the reaction rate at temperatures relevant to Type I x-ray bursts, but the particle decay widths for this level are not well known. The relative strengths of the proton decay branches to the ground and first excited state of $^{17}$F, which are critical to calculation of the reaction rate from the time-inverse reaction $^{17}$F(p,$\alpha$)$^{14}$O, are not fully constrained. Potentially competing alpha and even 2p decays may also be important. To address these discrepancies, $^{20}$Ne(p,t)$^{18}$Ne data from the JENSA gas jet target system were examined, utilizing a new technique to observe particle decays of the excited levels in $^{18}$Ne. The technique and preliminary results will be presented, along with plans for a future jet target system for reaccelerated beams from FRIB. [Preview Abstract] |
Wednesday, October 16, 2019 2:48PM - 3:00PM |
MB.00003: Proton Emission from $^{31}$S and the Astrophysical $^{30}$P$(p,\gamma)^{31}$S Reaction Sean Burcher, K.L. Jones, J. Hooker, J.M. Allmond, K.A. Chipps, S.D. Pain, J. Burke, R.O. Hughes, S. Ahn, H. Clark, H. Jayatissa, S. Ota, A. Saastamoinen, S. Upadhyayula, N. Cooper, C. Reingold, A. Simon, J.A. Cizewski, K. Schmidt The $^{30}$P$(p,\gamma)^{31}$S reaction rate has been identified as the largest remaining source of uncertainty in the abundances of intermediate-mass nuclei produced in classical nova explosions involving oxygen-neon white dwarfs, and is critical to interpreting the origin of certain meteoritic presolar grains. To inform the astrophysical proton capture rate, the $^{32}$S$(p,d)^{31}$S reaction has been used to populate proton unbound states in $^{31}$S. The Hyperion array was used to measure the reaction deuterons in coincidence with decay protons and γ rays. Angular correlations between the reaction products and decay protons have been measured and used to constrain the angular momentum of states in $^{31}$S above the proton threshold. In addition, proton-decay branching ratios have been measured for these states and used to inform resonance strengths. [Preview Abstract] |
Wednesday, October 16, 2019 3:00PM - 3:12PM |
MB.00004: Measuring Ne-19 alpha-Branching Ratios with the JENSA Gas-Jet Target D.W. Bardayan, P.D. O'Malley, K.A. Chipps, M. Matos, S.D. Pain, W.A. Peters, S.T. Pittman, K. Schmitt, M.S. Smith, S. Ahn, K.L. Jones, A. Sachs, P. Thompson, A. Kontos, H. Schatz, R.L. Kozub, B. Manning, S. Ota, U. Greife, J.C. Blackmon, L. Linhardt The $^{15}$O($\alpha,\gamma$)$^{19}$Ne reaction is an important trigger reaction leading to the rapid proton ($rp$) capture process in X-ray bursts. The primary uncertainty in determining its astrophysical rate is the uncertain $\alpha$ branching ratios of levels near $E_x=4.1$ MeV in $^{19}$Ne. These states have been populated in a study of the $^{20}$Ne($p,d$)$^{19}$Ne reaction utilizing the JENSA gas-jet target at Oak Ridge National Laboratory. $\alpha$ branching ratios have been extracted for several $^{19}$Ne levels. Preliminary results will be presented. [Preview Abstract] |
Wednesday, October 16, 2019 3:12PM - 3:24PM |
MB.00005: Measurement of near-threshold states in 12C using beta-delayed charged particle decay Jack Bishop, Grigory Rogachev, Sunghoon Ahn, Evgeny Koshchiy, Eric Aboud, Marina Barbui, Alexandra Bosh, Curtis Hunt, Joshua Hooker, Heshani Jayatissa, Rory O'Dwyer, Emmanuelle Pollaco, Cole Pruitt, Brian Roeder, Antti Saastamoinen, Lee Sobotka, Sriteja Upadhyayula The TexAT detector, an active target Time Projection Chamber (TPC), has recently been upgraded at the Cyclotron Institute at Texas A&M University. By utilizing the advantage of a TPC (4$\pi$ geometrical coverage), radioactive ion beams implanted into the chamber can be readily studied for rare processes. Of particular interest, to demonstrate the sensitivity of such a technique to probing 3-body correlations, is the decay mechanism of the $0_{2}^{+}$ state in $^{12}\mathrm{C}$, known as the Hoyle state. Using TexAT, this state is populated using $\beta^{+}$-decay of $^{12}\mathrm{N}$ and the $\beta$-delayed charged particles are measured and stopped inside the TPC. This talk will detail the latest results of this experiment and demonstrate the versatility of this technique. [Preview Abstract] |
Wednesday, October 16, 2019 3:24PM - 3:36PM |
MB.00006: Properties of Proton-Emitting ${}^{72,73}$Rb Isotopes D.E.M. Hoff, A.M. Rogers, S.M. Wang, P.C. Bender, K. Brandenburg, K. Childers, J. Clark, A.C. Dombos, E.R. Doucet, S. Jin, R. Lewis, S.N. Liddick, C.J. Lister, Z. Meisel, C.M. Morse, W. Nazarewicz, H. Schatz, K. Schmidt, D. Soltesz, S.K. Subedi, S. Waniganeththi Properties of proton-emitting nuclei at the limits of nuclear binding, along the proton dripline, impact the rapid proton-capture ($rp$) process and can reveal interesting nuclear structure. $\beta$-delayed protons emitted from $^{73}$Sr, produced by the fragmentation of a $^{92}$Mo primary beam on a Be target, were measured via ion implantation-decay correlations at the NSCL using the Beta-Counting Station (BCS), providing a direct measurement of the $^{73}$Sr lifetime. Low-energy protons were observed that are consistent with transistions from $^{73}$Rb(g.s.) to $^{72}$Kr(g.s.), and the resulting proton separation energy of $^{73}$Rb was determined by a Bayesian analysis of the data. A substantial amount of $^{72}$Rb was also observed allowing for a limit to be placed on the fragmentation cross section. [Preview Abstract] |
Wednesday, October 16, 2019 3:36PM - 3:48PM |
MB.00007: $\beta$-Delayed Proton Emission of ${}^{71}$Kr S. Waniganeththi, D.E.M. Hoff, A.M. Rogers, P.C. Bender, K. Brandenburg, K. Childers, J.A. Clark, A.C. Dombos, E.R. Doucet, S. Jin, R. Lewis, S.N. Liddick, C.J. Lister, Z. Meisel, C.M. Morse, H. Schatz, K. Schmidt, D. Soltesz, S.K. Subedi Mirror nuclei above $A\sim60$ play a key role in understanding the role of isospin in nuclear structure. The character of states in the $^{71}$Kr/$^{71}$Br mirror pair ($T=1/2$), that exhibit oblate-prolate shape coexistence, has been of significant interest for many years. Properties of this mirror system were investigated in an implant-decay experiment conducted at the NSCL using a beam containing $^{71}$Kr, produced by fragmentation of a $^{92}$Mo primary beam on a Be target and purified with the RF Fragment Separator, that was implanted into the Beta Counting Station surrounded by SeGA. $\beta$-decay branching to the lowest states of $^{71}$Br was observed as well as delayed-proton emission feeding the lowest states of $^{70}$Se. The results obtained from charged particle and $\gamma$-ray spectroscopy as well as implications for the structure of nuclei with $N \sim Z$ will be presented [Preview Abstract] |
Wednesday, October 16, 2019 3:48PM - 4:00PM |
MB.00008: Beta-Delayed Neutron Spectroscopy of Deformed Rubidium Isotopes with VANDLE Thomas King, Robert Grzywacz, Krzysztof Rykaczewski, Dan Stracener, Aleksandra Fijałkowska Beta-delayed neutron emission becomes an important or even the dominant the decay mode for many neutron-rich isotopes. The neutron emission after beta decay is often followed by, or competes with, the gamma-ray transformation. Therefore, the detection system needs to be optimized for simultaneous measurements of neutrons and gammas. A measurement of the complete decay pattern provides information necessary to extract the beta-strength distribution, which is sensitive to the nuclear structure of the involved nuclei. A series of measurements was performed at the On-Line Test Facility at Oak Ridge National Laboratory with the Versatile Array of Neutron Detectors at Low Energy (VANDLE). These experiments revisited decays of nuclei produced in proton induced fission of 238U. Unique data sets with neutron and gamma ray coincidences were collected. Achieving high coincidence efficiency required the addition of high-efficiency gamma-ray detectors consisting of LaBr3 (HARGiD) and NaI to VANDLE. Preliminary results on the decay of 97Rb will be presented. [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