Levels of [Formula Presented] Au: A detailed study of shape coexistence in an odd-mass nucleus

The decays of [Formula Presented] Hg (2.2 min; [Formula Presented]=13/2[Formula Presented] and [Formula Presented] Hg (2.4 min; [Formula Presented]=3/2[Formula Presented] have been studied with mass-separated sources at the UNISOR facility. Multiscaled spectra of [Formula Presented] rays, x rays, and conversion electrons, as well as [Formula Presented], [Formula Presented], [Formula Presented], and [Formula Presented] coincidences were obtained. Decay schemes have been constructed incorporating [Formula Presented]99[Formula Presented] of the decay intensities assigned to the high-spin and low-spin decays. The [Formula Presented]-ray gated conversion-electron spectra permitted determination of 367 conversion coefficients. A variety of coexisting band structures are established in [Formula Presented] Au. Some of these have near-identical analogs in the heavier odd-mass Au isotopes. The remaining bands reveal new degrees of freedom at low excitation energy in [Formula Presented] Au. Nine electric monopole [Formula Presented]0) transitions are observed to deexcite members of these new bands. The work represents an undertaking to achieve a benchmark in complete spectroscopy following radioactive decay. The most notable band structure in [Formula Presented] Au has two bands with identical spins, nearly identical relative energies, and electric monopole transitions connecting the favored members. These bands can be understood as [Formula Presented] and [Formula Presented] intruder configurations coupled to coexisting prolate or near-prolate [Formula Presented] 20[Formula Presented] cores having diabatic configurations that differ only in the number of protons occupying the [Formula Presented]=5 intruder configurations. © 1998 The American Physical Society