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Gray TJ, Allmond JM, Xu Z, King TT, Lubna RS, Crawford HL, Tripathi V, Crider BP, Grzywacz R, Liddick SN, Macchiavelli AO, Miyagi T, Poves A, Andalib A, Argo E, Benetti C, Bhattacharya S, Campbell CM, Carpenter MP, Chan J, Chester A, Christie J, Clark BR, Cox I, Doetsch AA, Dopfer J, Duarte JG, Fallon P, Frotscher A, Gaballah T, Harke JT, Heideman J, Huegen H, Holt JD, Jain R, Kitamura N, Kolos K, Kondev FG, Laminack A, Longfellow B, Luitel S, Madurga M, Mahajan R, Mogannam MJ, Morse C, Neupane S, Nowicki A, Ogunbeku TH, Ong WJ, Porzio C, Prokop CJ, Rasco BC, Ronning EK, Rubino E, Ruland TJ, Rykaczewski KP, Schaedig L, Seweryniak D, Siegl K, Singh M, Stuchbery AE, Tabor SL, Tang TL, Wheeler T, Winger JA, Wood JL. Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB. Phys Rev Lett 2023; 130:242501. [PMID: 37390416 DOI: 10.1103/physrevlett.130.242501] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 04/26/2023] [Indexed: 07/02/2023]
Abstract
Excited-state spectroscopy from the first experiment at the Facility for Rare Isotope Beams (FRIB) is reported. A 24(2)-μs isomer was observed with the FRIB Decay Station initiator (FDSi) through a cascade of 224- and 401-keV γ rays in coincidence with ^{32}Na nuclei. This is the only known microsecond isomer (1 μs≤T_{1/2}<1 ms) in the region. This nucleus is at the heart of the N=20 island of shape inversion and is at the crossroads of the spherical shell-model, deformed shell-model, and ab initio theories. It can be represented as the coupling of a proton hole and neutron particle to ^{32}Mg, ^{32}Mg+π^{-1}+ν^{+1}. This odd-odd coupling and isomer formation provides a sensitive measure of the underlying shape degrees of freedom of ^{32}Mg, where the onset of spherical-to-deformed shape inversion begins with a low-lying deformed 2^{+} state at 885 keV and a low-lying shape-coexisting 0_{2}^{+} state at 1058 keV. We suggest two possible explanations for the 625-keV isomer in ^{32}Na: a 6^{-} spherical shape isomer that decays by E2 or a 0^{+} deformed spin isomer that decays by M2. The present results and calculations are most consistent with the latter, indicating that the low-lying states are dominated by deformation.
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Affiliation(s)
- T J Gray
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J M Allmond
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Z Xu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - T T King
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R S Lubna
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - H L Crawford
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - V Tripathi
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - B P Crider
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Grzywacz
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - S N Liddick
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - A O Macchiavelli
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Miyagi
- Department of Physics, Technische Universität Darmstadt, Darmstadt, Germany
- ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
| | - A Poves
- Departamento de Fìsica Teórica and IFT-UAM/CSIC, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - A Andalib
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - E Argo
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - C Benetti
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - S Bhattacharya
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - C M Campbell
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - M P Carpenter
- Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J Chan
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - A Chester
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - J Christie
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - B R Clark
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - I Cox
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - A A Doetsch
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - J Dopfer
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - J G Duarte
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - P Fallon
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - A Frotscher
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - T Gaballah
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - J T Harke
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J Heideman
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - H Huegen
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - J D Holt
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
- Department of Physics, McGill University, Montréal, Quebec City H3A 2T8, Canada
| | - R Jain
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - N Kitamura
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - K Kolos
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - F G Kondev
- Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - A Laminack
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - B Longfellow
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S Luitel
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - M Madurga
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - R Mahajan
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - M J Mogannam
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - C Morse
- National Nuclear Data Center, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - S Neupane
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - A Nowicki
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - T H Ogunbeku
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - W-J Ong
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C Porzio
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C J Prokop
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - B C Rasco
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E K Ronning
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - E Rubino
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - T J Ruland
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - K P Rykaczewski
- Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - L Schaedig
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - D Seweryniak
- Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - K Siegl
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - M Singh
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA
| | - A E Stuchbery
- Department of Nuclear Physics and Accelerator Applications, Research School of Physics, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
| | - S L Tabor
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - T L Tang
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - T Wheeler
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - J A Winger
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - J L Wood
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA
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