Lifetimes of odd-spin yrast states inHg182

Abstract

Lifetimes of excited states in 182 Hg were extracted from recoil-gated γ -ray spectra and recoil-gated γ γ -coincidence matrices using the recoil distance Doppler-shift method. States were populated using the 96 Mo( 88 Sr,2n) 182 Hg fusion-evaporation reaction. Measured lifetimes allowed transition probabilities, transition quadrupole moments, quadrupole deformation parameters, and transition dipole moments to be deduced for the band formed by the odd-spin yrast states. The experimental results confirm the low degree of octupole collectivity in this mass region.

Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements inHg184,186and two-state mixing calculations

“…Analogous bands have been observed in the neighboring isotopes, specifically 178 Hg [34] and 180 Hg [35] and their structure discussed in terms of octupole correlations. Lifetime measurements of states in this band in 182 Hg have been performed and a consistency in the structure of these states has been extended to 184 Hg using the energy displacement of states differing by 3h [19]. The quadrupole moment measured here for the 9 3 → 7 3 transition in 184 Hg, |Q t | = 5.6(7) eb, is similar to that of the even-spin yrast band, |Q t | 7.7 eb, although it is smaller than those measured in the lighter isotopes.…”

Nuclear shape coexistence: A study of the even-even Hg isotopes using the interacting boson model with configuration mixing

“…Recent developments in the experimental methods to study the nuclear structure properties of these neutrondeficient Hg nuclei, allowed to substantially increase the nuclear structure data basis: (β + /EC)-decay of 180 Tl [129] and in-beam conversion-electron spectroscopy [130]. Besides the new information on the low-spin states below E x ∼ 2 MeV, lifetimes up to spin J π = 8 + (10 + ) have been measured from using Recoil-Decay tagged (RDT) γ-rays, using the recoil distance Doppler-shift (RDDS) method [40,41] for mass A=180 and A=182. This recent information largely extends the early data (see refs.…”

“…A more stringent test than a good reproduction of the energy systematics comes from calculating those observables that probe the corresponding wave functions and a comparison with the data. Recent experimental efforts have given rise to absolute B(E2) values along the yrast band, deduced from lifetime measurements [40,41], as well as through Coulomb excitation at ISOLDE-CERN [54,146], the latter also giving first results for the quadrupole moments of the 2 + 1 and 2 + 2 states. The systematics for a number of important E2 transitions and the electric quadrupole moments are presented in figures 5, 6, and 7, respectively.…”

“…The discovery of three shape coexisting configurations in the mid-shell 186 Pb nucleus (at N=104) [36] even accelerated the accumulation of new data since 2010. Very recent experimental campaigns have largely extended our knowledge beyond the excitation energies of intruding bands by providing information on nuclear lifetimes [37][38][39][40][41], nuclear charge radii [42][43][44], 2 + 1 gyromagnetic factors [45,46], α-decay hindrance factors [47][48][49][50][51][52][53] and, very recently, Coulomb excitation using radioactive beams at REX-ISOLDE (CERN) [54].…”

Excited states and reduced transition probabilities in Os168

“…Instead these lifetimes were obtained using γ -ray singles data correlated with recoil implantations followed within 6.3 s by a characteristic α decay of 168 Os [30] in the same DSSD pixel. The influence of the unobserved feeding transitions on the lifetime of interest cannot be eliminated when extracting lifetimes from singles γ -ray spectra, so it was assumed that the time behavior of the observed and unobserved feeding was similar [27,31].…”