On the origin of the anomalous behaviour of 2+ excitation energies in the neutron-rich Cd isotopes
On the origin of the anomalous behaviour of 2+ excitation energies in the neutron-rich Cd isotopes
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DOI：
10.1016/j.physletb.2008.08.072
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发表时间：
2008-09
影响因子：
4.4
通讯作者：
T. R. Rodr'iguez;J. Egido;A. Jungclaus
中科院分区：
文献类型：
--
作者：
T. R. Rodr'iguez;J. Egido;A. Jungclaus
最近利用β衰变和同分异构体光谱获得的实验结果表明，富中子Cd同位素在接近N=82壳层闭合时，第一激发态2+的能量具有不寻常的行为。为了解释这一意想不到的趋势，有人提出了核结构远稳定的变化，即在距离双magic132Sn只有两个质子空穴的130cd中已经存在的N=82壳层间隙的猝灭。我们利用现代超平均场技术和高格尼力研究了从N=50到N=82的Cd同位素中2+能量的行为，即跨越主中子壳层的整个跨度。我们证明了在接近N=82壳闭合的128cd中观察到的低2+激发能是该核的双魔法特性的结果，该特性有利于扁圆变形，从而有利于长形构型而不是球形构型。
Recent experimental results obtained using β decay and isomer spectroscopy indicate an unusual behaviour of the energies of the first excited 2+states in neutron-rich Cd isotopes approaching the N=82 shell closure. To explain the unexpected trend, changes of the nuclear structure far-off stability have been suggested, namely a quenching of the N=82 shell gap already in130Cd, only two proton holes away from doubly magic132Sn. We study the behaviour of the 2+energies in the Cd isotopes from N=50 to N=82, i.e. across the entire span of a major neutron shell using modern beyond mean field techniques and the Gogny force. We demonstrate that the observed low 2+excitation energy in128Cd close to the N=82 shell closure is a consequence of the doubly magic character of this nucleus for oblate deformation favoring thereby prolate configurations rather than spherical ones.