Shape staggering of midshell mercury isotopes from insource laser spectroscopy compared with densityfunctionaltheory and Monte Carlo shellmodel calculations
Abstract
Neutrondeficient ^{Hg}−185_{177} isotopes were studied using insource laser resonanceionization spectroscopy at the CERNISOLDE radioactive ionbeam facility in an experiment combining different detection methods tailored to the studied isotopes. These include either αdecay tagging or multireflection timeofflight gating for isotope identification. The endpoint of the oddeven nuclear shape staggering in mercury was observed directly by measuring for the first time the isotope shifts and hyperfine structures of ^{Hg}−180_{177}. Changes in the meansquare charge radii for all mentioned isotopes, magnetic dipole, and electric quadrupole moments of the oddA isotopes and arguments in favor of I =7 /2 spin assignment for ^{Hg},179_{177} were deduced. Experimental results are compared with density functional theory (DFT) and Monte Carlo shell model (MCSM) calculations. DFT calculations using Skyrme parametrizations predict a jump in the charge radius around the neutron N =104 midshell, with an oddeven staggering pattern related to the coexistence of nearly degenerate oblate and prolate minima. This neardegeneracy is highly sensitive to many aspects of the effective interaction, a fact that renders perfect agreement with experiments out of reach for current functionals. Despite this inherent difficulty, the SLy5s1 and a modified UNEDF 1^{SO} parametrization predict a qualitatively correct staggering that is off by two neutron numbers. MCSM calculations of states with the experimental spins and parities show good agreement for both electromagnetic moments and the observed charge radii. A clear mechanism for the origin of shape staggering within this context is identified: a substantial change in occupancy of the proton π h_{9 /2} and neutron ν i_{13 /2} orbitals.
 Publication:

Physical Review C
 Pub Date:
 April 2019
 DOI:
 10.1103/PhysRevC.99.044306
 arXiv:
 arXiv:1902.11211
 Bibcode:
 2019PhRvC..99d4306S
 Keywords:

 Nuclear Experiment;
 Nuclear Theory
 EPrint:
 19 pages, 18 figures