The interacting Boson Model applied to the mercury isotopes

Abstract

The even isotopes of mercury have been systematically studied using the Interacting Boson Model (IBM). In order to treat shape coexistence in the light isotopes, two separate IBM calculations were performed with different configurations, which were subsequently mixed. The four Hamiltonian parameters, which were allowed to vary freely from isotope to isotope, were found to be consistent with the corresponding IBM parameters used for platinum and osmium. Overall, the calculated energy spectra and electromagnetic properties are in reasonable agreement with experiment.

Shape coexistence in the light Po isotopes

“…Thus, in this analysis, the lowering of the deformed band arises mainly from the decrease in the energy required to excite the two protons across the Z=82 shell gap, which is related to the parameter . This result is just the opposite to that found for the Hg isotopes [61], where had to be held constant at 4.0 MeV and the deformed band fell in energy due to the increased collectivity, i.e. increasing N N (larger value of N for the intruder band times an increasing value of N ).…”

“…The mixing of a regular band and a deformed band has been well reproduced within the proton-neutron Interacting Boson Model (IBM-2) for several isotopic chains, e.g., the Hg and the Mo isotopes [60,61,62]. The general formalism, described in Ref.…”

Nuclear matrix elements for double-βdecay

“…A paper with those for 48 Ti is in preparation [109]. The quality of these, as well as of the unpublished results for 96 Zr is equal to that of the results obtained previously [95][96][97][98][99][100][101][102][103][104][105][106][107]. For the semimagic nuclei 116−124 Sn and 136 Xe, we have obtained the parameters by a fit to the energy of the low-lying states using the same procedure as in Ref.…”

“…For most nuclei, the Hamiltonian parameters are taken from the literature [95][96][97][98][99][100][101][102][103][104][105][106][107]. The values of the Hamiltonian parameters, as well as the references from which they were taken, are given in Table XXIII.…”

Shape coexistence in lead isotopes in the interacting boson model with a Gogny energy density functional

“…In the case of Pb isotopes with three low-lying 0 + levels, the model consists of three different Hamiltonians corresponding to 0p-0h, 2p-2h, and 4p-4h configurations. The idea of configuration mixing in the IBM framework has been applied to spectroscopic analyses [9,[16][17][18][19], algebraic features [20,21], and geometry and phases [22][23][24] associated with the shape coexistence observed in the lead and mercury region. In these studies, the parameters for the configuration mixing IBM Hamiltonian have been extracted from a fit to the experimental spectra and transition rates.…”