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 EA: Structure of Proton-Rich Nuclei |
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Chair: Corina Andreoiu, Simon Fraser University Room: Salon 1 |
Tuesday, October 15, 2019 8:30AM - 9:06AM |
EA.00001: In-beam gamma-ray spectroscopy of neutron-deficient nuclei - News from the proton-rich side Invited Speaker: Alexandra Gade Nuclei on the neutron-deficient side of the nuclear chart have attracted attention in recent years. The proximity of the N$=$Z line and the proton dripline offers a unique laboratory for nuclear structure studies with relevance to nuclear astrophysics. This presentation will highlight recent results from the National Superconducting Cyclotron Laboratory obtained using the powerful experimental approach of in-beam gamma-ray spectroscopy. [Preview Abstract] |
Tuesday, October 15, 2019 9:06AM - 9:42AM |
EA.00002: $^{\mathrm{11}}$O and other invariant mass results at, beyond or isobarically anchored to the proton drip line Invited Speaker: Lee Sobotka The reconstruction of the continuum of light nuclei using the invariant mass technique has allowed us to: observe new isotopes, find many new excited states, improve level properties of known levels, find the only case of sequential 2p-2p decay, discover 2p decay between isobaric analog states, study the decay of the Hoyle state, find an unappreciated mechanism for the generation of extreme nuclear spin alignments, complete or reduce uncertainties of several isospin multiplets, and find new cases of near-threshold resonances. Our work impacts every isobar from A$=$5 to A $=$ 18. This talk will have very brief discussions of how these experiments are done, a survey of some of the results mentioned above and then focus on the recent discovery of $^{\mathrm{11}}$O (the mirror of the iconic $^{\mathrm{11}}$Li) and explaining near-threshold resonances in $^{\mathrm{9}}$Li and $^{\mathrm{10}}$Be. In these cases continuum cognizant shell models are exploited to shed light on the not-so-obvious entanglement of the continuum (or continua) with structure. [Preview Abstract] |
Tuesday, October 15, 2019 9:42AM - 10:18AM |
EA.00003: Recent studies of exotic nuclei near the self-conjugate doubly-magic $^{\mathrm{100}}$Sn nucleus Invited Speaker: Dariusz Seweryniak The exotic proton-rich self-conjugate doubly-magic nucleus $^{\mathrm{100}}$Sn is one of the corner stones of nuclear structure. The $^{\mathrm{100}}$Sn region provides a stringent test for the shell model far away from the line of stability. The $^{\mathrm{100}}$Sn nucleus is the fastest known Gamow-Teller $\beta $ emitter. Its large binding energy is signaled by the existence of an island of proton and $\alpha $ emitters decaying towards the N$=$Z$=$50 closed shells. Also, the astrophysical rp-process was proposed to terminate with $\alpha $ decays of light Te isotopes. Despite prohibitively small production cross sections, several exotic nuclei near $^{\mathrm{100}}$Sn have been studied recently using various probes at the ATLAS facility at the Argonne National Laboratory. 1) First evidence for the $\alpha $-decay chain $^{\mathrm{108}}$Xe-$^{\mathrm{104}}$Te into $^{\mathrm{100}}$Sn was observed. This is only the second case of $\alpha $ decay into a doubly-magic nucleus besides $^{\mathrm{212}}$Po, which has been a benchmark of microscopic models of $\alpha $ decay. The reduced $\alpha $-decay widths deduced for $^{\mathrm{108}}$Xe and $^{\mathrm{104}}$Te are larger than that for $^{\mathrm{212}}$Po supporting the expectation that the enhanced interaction between protons and neutrons, which occupy the same orbitals, leads to a larger $\alpha $-particle preformation, which results in the so-called superallowed $\alpha $ decay. 2) A small proton-decay branch was found in $^{\mathrm{108}}$I. The proton separation energy in $^{\mathrm{104}}$Sb, deduced using the measured $^{\mathrm{108}}$I proton energies, indicates that the rp-process does not form a Sn-Sb-Te cycle at $^{\mathrm{103}}$Sn which is delayed until heavier Sn isotopes. 3) Excited states in the fast $^{\mathrm{105}}$Te $\alpha $ emitter were studied for the first time using in-beam $\gamma $-ray spectroscopy to shed light on the long standing issue of the ordering of the d$_{\mathrm{5/2}}$ and g$_{\mathrm{7/2}}$ single-neutron orbitals in $^{\mathrm{101}}$Sn. [Preview Abstract] |
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