Global Calculations of Ground-State Axial Shape Asymmetry of Nuclei

Abstract

Important insight into the symmetry properties of the nuclear ground-state (gs) shape is obtained from the characteristics of low-lying collective energy-level spectra. In the 1950s, experimental and theoretical studies showed that in the gs many nuclei are spheroidal in shape rather than spherical. Later, a hexadecapole component of the gs shape was identified. In the 1970-1995 time frame, a consensus that reflection symmetry of the gs shape was broken for some nuclei emerged. Here we present the first calculation across the nuclear chart of axial symmetry breaking in the nuclear gs. We show that we fulfill a necessary condition: Where we calculate axial symmetry breaking, characteristic gamma bands are observed experimentally. Moreover, we find that, for those nuclei where axial asymmetry is found, a systematic deviation between calculated and measured masses is removed.

Spectroscopy ofHo144using recoil-isomer tagging

“…The extremely neutron-deficient A = 130-150 region of the nuclear chart in which it lies is at the boundary between regions with prolate and oblate nuclear shapes and is predicted to show numerous axially asymmetric, γ -soft nuclei [2]. This asymmetry is driven by the competing effects of the proton and neutron h 11/2 orbitals, which both lie close to the Fermi surface for these nuclei.…”

High-spin level structure ofRh115: Evolution of triaxiality in odd-even Rh isotopes

“…Moreover, the global calculations of nuclear ground states by Möller et al [34] predict deviations from axial symmetry in a region around Ru. According to Ref.…”

Large-scale calculations of nuclear-structure data for simulation data bases

“…An indication that the original adjustment was not quite optimum is that the mean error µ th 106 Ru is triaxial, as is the case for several hundred other nuclei across the nuclear chart, for details see ref. [7].…”

“…[7], which focused on the effect of triaxiality on the nuclear ground state. From this calculation we also determine the shape and energy of shape-isomer minima and the saddle heights between all pairs of minima by immersion techniques.…”