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

Abstract

Excited states in the proton-unbound nuclide Au177 were populated in the Mo92(Sr88, p2n) reaction and identified using the Jurogam-II and GREAT spectrometers in conjunction with the RITU gas-filled separator at the University of Jyväskylä 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 1h11/2 proton hole to the excited 02+ configuration in the Hg178 core. Although these configurations might be expected to follow the parabolic trend of core Hg(02+) states as a function of neutron number, the electromagnetic decay paths from the strongly coupled band in Au177 are markedly different from those observed in the heavier isotopes above the midshell. This indicates that a significant change in the structure of the underlying A+1Hg core occurs below the neutron midshell.