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

Abstract

Background:The Po, Pb, Hg, and Pt region is known for the presence of coexisting structures that correspond to different particle-hole configurations in the shell model language or equivalently to nuclear shapes with different deformation. Purpose: We intend to study the configuration mixing phenomenon in the Hg isotopes and to understand how different observables are influenced by it. Method: We study in detail a long chain of mercury isotopes, Hg, using the interacting boson model with configuration mixing. The parameters of the Hamiltonians are fixed through a least-squares fit to the known energies and absolute B(E2) transition rates of states up to 3 MeV. Results: We obtained the IBM-CM Hamiltonians and we calculate excitation energies, B(E2)'s, quadrupole shape invariants, wave functions, isotopic shifts, and mean-field energy surfaces. Conclusions:We obtain a fairly good agreement with the experimental data for all the studied observables and we conclude that the Hamiltonian and the states we obtain constitute a good approximation to the Hg isotopes.

Shell-model-based deformation analysis of light cadmium isotopes

“…These methods have been used in a large number of recent papers (in particular in the region of the Ge, Kr, Mo, Ru and Pd nuclei [90][91][92][93][94][95], as well as in the much heavier Pb mass region (W, Os, Pt, Hg, Po isotopes) [96][97][98][99][100][101].…”

“…[65][66][67]). See also reference [68] for a recent review on the structure of 100 Sn and neighboring nuclei including the light Cd isotopes.…”

Shape Coexistence in the Neutron-Deficient Even-EvenHg182−188Isotopes Studied via Coulomb Excitation

“…In the IBM approach [32], whereby particle-hole pair excitations across the Z ¼ 82 closed shell are explicitly included (for a similar calculation see, e.g., [6,33]), agreement between experiment and calculations for the SSM sum is noticed. However, as in the case of the BMF calculations, only partial agreement between experiment and theory is observed for the sum of triple product of IBM ME2's.…”

“…The disagreements for the two models are not understood and point to missing ingredients in the calculations. This is further addressed in [32].…”

“…The lack of precision on key matrix elements, especially in 186;188 Hg, prevents us from drawing firm conclusions on the nature of the deformation of the ground ( 186 Hg) or excited ( 186;188 Hg) 0 þ states. Sums of the products of the relevant ME2'sg i v e ni n Table I, were compared to the equivalent sums (including to the 2 þ 2 state) calculated from beyond mean field (BMF) [9] and interacting boson-based models (IBM) [32] (Fig. 3).…”