Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB
Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB
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FRIB 观测到的 N=20 形状反转岛的微秒异构体
DOI：
10.1103/physrevlett.130.242501
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发表时间：
2023
影响因子：
8.6
通讯作者：
Liddick, S. N.
中科院分区：
文献类型：
--
作者：
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.
本文报道了稀土同位素束流装置（FRIB）首次实验的激发态光谱。用FRIB衰变站引发剂（FDSi）通过224-和401- kev射线级联与原子核重合，观察到异构体。这是该地区唯一已知的微秒异构体。这个核是形状反转岛的中心，是球壳模型、变形壳模型和初始理论的交叉点。它可以表示为质子空穴与中子粒子的耦合。这种奇奇耦合和异构体的形成提供了一种对潜在形状自由度的敏感测量，其中球体到变形形状反转的开始是在885 keV的低洼变形状态和1058 keV的低洼形状共存状态。我们对625 kev的异构体提出了两种可能的解释：一种是由变形自旋异构体衰变的非球形异构体。本文的结果和计算结果与后者最为一致，表明低洼状态以变形为主。
Excited-state spectroscopy from the first experiment at the Facility for Rare Isotope Beams (FRIB) is reported. Aisomer was observed with the FRIB Decay Station initiator (FDSi) through a cascade of 224- and 401-keVrays in coincidence withnuclei. This is the only known microsecond isomer () in the region. This nucleus is at the heart of theisland of shape inversion and is at the crossroads of the spherical shell-model, deformed shell-model, andab initiotheories. It can be represented as the coupling of a proton hole and neutron particle to,. This odd-odd coupling and isomer formation provides a sensitive measure of the underlying shape degrees of freedom of, where the onset of spherical-to-deformed shape inversion begins with a low-lying deformedstate at 885 keV and a low-lying shape-coexistingstate at 1058 keV. We suggest two possible explanations for the 625-keV isomer in: aspherical shape isomer that decays byor adeformed spin isomer that decays by. The present results and calculations are most consistent with the latter, indicating that the low-lying states are dominated by deformation.