Evolution of collectivity inHg180andHg182

Abstract

Lifetimes of yrast states in 180 Hg up to the 8 + state and of the 9 − state have been extracted from recoil-decay tagged γ -ray spectra by using the recoil distance Doppler-shift method. In addition, lifetimes of yrast states up to the 10 + state in 182 Hg have been extracted from recoil-gated γ γ -coincidence spectra. The present study addresses the evolution of collectivity of two competing shapes in neutron-deficient Hg nuclei as a function of A and the configuration mixing at low spin.

Shape evolution and the role of intruder configurations in Hg isotopes within the interacting boson model based on a Gogny energy density functional

“…6). However, this contradicts the experimental finding [12,67,68] that the ground state of these nuclei is weakly deformed oblate configuration. The reason for the contradiction is that, in the microscopic energy surfaces of 180,182 Hg (cf.…”

Nuclear shape coexistence in Po isotopes: An interacting boson model study

“…1) indicated a break in the energy scale observed for the heavier masses, where the energy of the 2 period have been performed at the Department of Physics at the University of Jyväskylä using the recoil-decay-tagging (RDT) technique, studying prompt and delayed γ rays down to mass A = 190 [110,111]. Moreover, lifetimes could be derived making use of the RDT technique in recoil distance Doppler-shift experiments for masses A = 194 [112,113] and A = 196 [114]. The experimental situation for the Po isotones down to A = 190 has been summarized by Julin et al [8].…”

“…The above results were confirmed later by Smirnova et al [126], this time using a self-consistent Hartree-Fock-Bogoliubov approach using the SLy4 Skyrme force [26], indicating rather wide minima in A = 196-194, a lowest oblate minimum at A = 192 and A = 190, and a turning into prolate at A = 188. Triggered by the new data on masses A = 196 and A = 194, more detailed beyond-mean-field studies were carried out [112][113][114], highlighting a detailed comparison on energy spectra and E2 properties, indicating the interplay of an oblate and a more spherical structure (vibrational). In their analysis, the authors point towards a rather pure intruder character of the whole yrast band, including the ground state.…”

“…They have calculated energy spectra (general systematics), as well as charge radii, ρ 2 (0 [114]). Because their formulation is within a mean-field context, invoking the concept of nuclear shapes (spherical, oblate, prolate), it is not always possible to compare with the present IBM-CM approach in which the model space is restricted to 0p-0h and 2p-2h excitations across the Z = 82 closed shell.…”

“…In particular, for the Po nuclei (see Refs. [8,85,89,90,111,114]), we cover the 106 N 114 (190 A 198), region, with the results presented in Fig. 17.…”