Neutron-unbound states in 31Ne

Chrisman, D.; Kuchera, A. N.; Baumann, T.; Blake, A.; Brown, B. A.; Brown, J.; Cochran, C.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Guèye, P.; Karrick, H.; Liu, H.; McDonaugh, J.; Mix, T.; Monteagudo, B.; Redpath, T. H.; Rogers, W. F.; Seaton-Todd, R.; Spyrou, A.; Stiefel, K.; Thoennessen, M.; Tostevin, J. A.; Votaw, D.

doi:10.1103/physrevc.104.034313

Neutron-unbound states in ³¹Ne

Journal Article · Wed Sep 15 00:00:00 EDT 2021 · Physical Review C

DOI:https://doi.org/10.1103/physrevc.104.034313· OSTI ID:1827200

Chrisman, D. ^[1]; Kuchera, A. N. ^[2]; Baumann, T. ^[3]; Blake, A. ^[4]; ^[3]; Brown, J. ^[5]; Cochran, C. ^[5]; DeYoung, P. A. ^[6]; Finck, J. E. ^[7]; ^[8]; ^[9]; ^[8]; Liu, H. ^[3]; ^[8]; Mix, T. ^[5]; Monteagudo, B. ^[3]; Redpath, T. H. ^[10]; ^[11]; ^[2]; Spyrou, A. ^[3] more »

Michigan State Univ., East Lansing, MI (United States); Michigan State University
Davidson College, NC (United States)
Michigan State Univ., East Lansing, MI (United States)
Hampton Univ., Hampton, VA (United States)
Wabash College, Crawfordsville, IN (United States)
Hope College, Holland, MI (United States)
Central Michigan Univ., Mount Pleasant, MI (United States)
Augustana College, Rock Island, IL (United States)
Michigan State Univ., East Lansing, MI (United States); Hampton Univ., Hampton, VA (United States)
Michigan State Univ., East Lansing, MI (United States); Virginia State Univ., Petersburg, VA (United States)
Indiana Wesleyan Univ., Marion, IN (United States)
Michigan State Univ., East Lansing, MI (United States); American Physical Society (APS), Ridge, NY (United States)
Univ. of Surrey, Guildford (United Kingdom)
Michigan State Univ., East Lansing, MI (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Background: The Island of Inversion near the N = 20 shell gap is home to nuclei with reordered single-particle energy levels compared to the spherical shell model. Studies of ³¹Ne have revealed that its ground state has a halo component, characterized by a valence neutron orbiting a deformed ³⁰Ne core. This lightly-bound nucleus with a separation energy of only S_n = 170 keV is expected to have excited states that are neutron unbound. Purpose: The purpose of this experiment was to investigate the low-lying excited states in ³¹Ne that decay by the emission of a single neutron. Methods: An 89 MeV/u ³³Mg beam impinged on a segmented Be reaction target. Neutron unbound states in ³¹Ne were populated via a two-proton knockout reaction. The ³⁰Ne fragment and associated neutron from the decay of ³¹Ne were detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant mass spectroscopy was used to reconstruct the two-body decay energy (³⁰Ne + n). Results: The two-body decay energy spectrum exhibits two features: a low-lying peak at 0.30 ± 0.17 MeV and a broad enhancement at 1.50 ± 0.33 MeV, each fit with an energy-dependent asymmetric Breit-Wigner line shape representing a resonance in the continuum. Accompanying shell model calculations using the FSU interaction within NuShellX, combined with cross-section cal culations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in ³¹Ne. Conclusions: In this study, excited states in ³¹Ne were observed for the first time. Transitions from calculated shell model final states in ³¹Ne to bound states in ³⁰Ne are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating ³¹Ne states as well as spectroscopic factors pertaining to the decay of ³¹Ne into ³⁰Ne are used to examine the results within the context of the shell model expectations.

View Accepted Manuscript (DOE)

Research Organization:: Michigan State Univ., East Lansing, MI (United States)

Sponsoring Organization:: National Science Foundation (NSF); Science and Technology Facilities Council (STFC) (United Kingdom); USDOE National Nuclear Security Administration (NNSA)

Grant/Contract Number:: NA0000979; NA0003180

OSTI ID:: 1827200

Journal Information:: Physical Review C, Journal Name: Physical Review C Journal Issue: 3 Vol. 104; ISSN 2469-9985

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

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