Bulletin of the American Physical Society
6th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Sunday–Friday, November 26–December 1 2023; Hawaii, the Big Island
Session E03: Minisymposium: Single-Particle Strengths of Exotic Nuclei Probed by Transfer and Knock-Out Reactions |
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Chair: Rituparna Kanungo, Saint Mary's University (Canada) Room: Hilton Waikoloa Village Kings 3 |
Wednesday, November 29, 2023 7:00PM - 7:30PM |
E03.00001: Quenching of Cross Sections in Direct Reactions Invited Speaker: Benjamin Kay The strengths of single-particle transitions probed in direct reactions appear to be quenched by correlations. The degree of quenching is around 0.6 for stable nuclei. This factor seems to be independent of the probe used, the mass of the system, the orbital angular momentum of the nucleon added or removed from the system, and its separation energy. It is the same for protons and neutrons. Typical probes include single-nucleon transfer reactions carried out at a few MeV per nucleon above the barrier, intermediate energy heavy-ion induced knockout reactions, quasifree (p,2p) and (p,pn) scattering, and electron-induced knockout. The difference between the proton and neutron separation energies (ΔS) is relatively small for stable nuclei, varying between approximately –10 MeV and +10 MeV. The differences are much larger for nuclei far from stability, exceeding –/+20 MeV in some cases. Over the last two decades, a wealth of data using intermediate energy heavy-ion induced knockout reactions has revealed a striking trend in the degree of quenching, expressed as the reduction factor R (the ratio of experimental and theoretical inclusive cross sections), versus ΔS [1]. There are limited data available over such a range of ΔS using other probes, with only a handful of transfer-reaction and (p,2p) and (p,pn) results. However, there is a strong contrast between the R factors from intermediate energy heavy-ion induced knockout reactions and these other probes, for which there is not yet a robust theoretical explanation. I will give an overview of the status of this topic with a focus on results, opportunities, and techniques to explore quenching in exotic nuclei using transfer reactions in the coming decade. |
Wednesday, November 29, 2023 7:30PM - 7:45PM |
E03.00002: Abstract Withdrawn
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Wednesday, November 29, 2023 7:45PM - 8:00PM |
E03.00003: Constraining the 30P(p,γ)31S reaction using 30P(d,pγ)31P with GODDESS Rajesh Ghimire, Kate Jones, Steven D Pain, Andrew Ratkiewicz, Jolie A Cizewski, Joshua L Hooker, Harrison E Sims, Chad Ummel, Gwenaelle Seymour, Gemma L Wilson During classical nova nucleosynthesis, the 30P(p,γ)31S reaction rate critically affects the mass flow into the A=30-40 range, impacting the abundances of isotopes of phosphorus, sulfur, and silicon. Direct measurement of the (p,γ) reaction is not currently possible due to insufficient beam intensities. The rate of this reaction depends on undetermined spectroscopic strengths of low-lying resonances in 31S, located between 6 and 7 MeV in excitation energy. Due to experimental challenges to measure the proton spectroscopic factors on unstable nuclei, we performed a 30P(d,pγ)31P neutron transfer reaction measurement using the newly commissioned GODDESS (GRETINA-ORRUBA: Dual Detectors for Experimental Structure Studies) detection system—with an 8 MeV/u 30P beam, from RAISOR at ATLAS, in order to provide constraints on the spectroscopic strengths for 31S levels via mirror symmetry. Details of the experiment and progress in data analysis, including excitation energy spectrums, proton-gamma matrices, angular distributions, spectroscopic factors, and reaction rates, will be presented. |
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