De-excitation of the strongly coupled band in ~(177)Au and implications for core intruder configurations in the light Hg isotopes

摘要

Excited states in the proton-unbound nuclide ~(177)Au were populated in the ~(92)Mo(~(88)Sr, p2n) reaction and identified using the Jurogam-Ⅱ and GREAT spectrometers in conjunction with the RITU gas-filled separator at the University of Jyvaeskylae Accelerator Laboratory. A strongly coupled band and its decay path to the 11/2~-α-decaying isomer have been identified using recoil-decay tagging. Comparisons with cranked Hartree- Fock-Bogoliubov (HFB) calculations based on Skyrme energy functionals suggest that the band has a prolate deformation and is based upon coupling the odd 1h_(11/2) proton hole to the excited 0~+_2 configuration in the ~(178)Hg core. Although these configurations might be expected to follow the parabolic trend of core Hg(0~+_2 ) states as a function of neutron number, the electromagnetic decay paths from the strongly coupled band in ~(177)Au are markedly different from those observed in the heavier isotopes above themidshell. This indicates that a significant change in the structure of the underlying ~(A+1)Hg core occurs below the neutron midshell.