Shape coexistence close to N = 50 in the neutron-rich isotope ⁸⁰ Ge investigated by IBM-2

Abstract

The properties of the low-lying states, especially the relevant shape coexistence in 80 Ge, close to one of most neutron-rich doubly magic nuclei at N = 50 and Z = 28, have been investigated within the framework of the proton-neutron interacting model (IBM-2). Based on the fact that the relative energy of the d neutron boson is different from that of the proton boson, the calculated energy levels of low-lying states and E2 transition strengths can reproduce the experimental data very well. Particularly, the first excited state 0 + 2 , which is intimately related to the shape coexistence phenomenon, is reproduced quite nicely. The ρ 2 (E0,0 + 2 → 0 + 1 ) transition strength is also predicted. The experimental data and theoretical results indicate that both collective spherical and γ-soft vibration structures coexist in 80 Ge.

Absence of Low-Energy Shape Coexistence in Ge80 : The Nonobservation of a Proposed Excited 02+

“…Large-scale shell model calculations support this finding, and suggest that the 0 þ 2 level may be located near 2 MeV. These also agree with the theoretical trend found in the IBM [7], but contradict the recent IBM-2 calculations [9].…”

Absence of Low-Energy Shape Coexistence in $^{80}$Ge: The Nonobservation of a Proposed Excited 0$_2^+$ Level at 639 keV

“…Large-scale shell model calculations support this finding, and suggest that the 0 + 2 level may be located near 2 MeV. These also agree with the theoretical trend found in the IBM [7],but contradict the recent IBM-2 calculations [9].…”

Shape coexistence in 76Se within the neutron–proton interacting boson model

“…K Nomura et al studied the structural evolution in selenium nuclei by means of the mapped IBM based on the Gogny energy density functional [2]. In this paper, we extend our previous studies of IBM-2 on the shape coexistence to 76 Se nucleus [31][32][33][34][35][36][37][38][39][40][41], and extract the associated signatures of shape coexistence by analyzing the lowlying level scheme and M1 transition transition rates in addition to E2 transitons. We expect to improve the description of + 0 2 state in the framework of IBM-2 which is important for the shape coexistence.…”