Details

Autor(en) / Beteiligte

• Gray, T J
• Allmond, J M
• Xu, Z
• King, T T
• Lubna, R S
• Crawford, H L
• Tripathi, V
• Crider, B P
• Grzywacz, R
• Liddick, S N
• Macchiavelli, A O
• Miyagi, T
• Poves, A
• Andalib, A
• Argo, E
• Benetti, C
• Bhattacharya, S
• Campbell, C M
• Carpenter, M P
• Chan, J
• Chester, A
• Christie, J
• Clark, B R
• Cox, I
• Doetsch, A A
• Dopfer, J
• Duarte, J G
• Fallon, P
• Frotscher, A
• Gaballah, T
• Harke, J T
• Heideman, J
• Huegen, H
• Holt, J D
• Jain, R
• Kitamura, N
• Kolos, K
• Kondev, F G
• Laminack, A
• Longfellow, B
• Luitel, S
• Madurga, M
• Mahajan, R
• Mogannam, M J
• Morse, C
• Neupane, S
• Nowicki, A
• Ogunbeku, T H
• Ong, W-J
• Porzio, C
• Prokop, C J
• Rasco, B C
• Ronning, E K
• Rubino, E
• Ruland, T J
• Rykaczewski, K P
• Schaedig, L
• Seweryniak, D
• Siegl, K
• Singh, M
• Stuchbery, A E
• Tabor, S L
• Tang, T L
• Wheeler, T
• Winger, J A
• Wood, J L

Titel

Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB

Ist Teil von

• Physical review letters, 2023-06, Vol.130 (24), p.242501-242501, Article 242501

Ort / Verlag

United States

Erscheinungsjahr

2023

Quelle

American Physical Society

Beschreibungen/Notizen

• 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.