Identification of γ rays from Au172 and α decays of Au172, Ir168, and Re164

The very neutron deficient odd-odd nucleus Au172 was studied in reactions of 342 and 348 MeV Kr78 beams with an isotopically enriched Ru96 target. The α decays previously reported for Au172 were confirmed and the decay chain extended down to Tm152 through the discovery of a new α-decaying state in Re164 [Eα=5623(10)keV; t1/2=864-110+150 ms; bα=3(1)%]. Fine structure in these α decays of Au172 and Ir168 were identified. A new α-decaying state was also observed and assigned as the ground state in Au172 [Eα=6762(10) keV; t1/2=22-5+6 ms]. This decay chain was also correlated down to Tm152 through previously reported α decays. Prompt γ rays from excited states in Au172 have been identified using the recoil-decay tagging technique. The partial level scheme constructed for Au172 indicates that it has an irregular structure. Possible configurations of the α-decaying states in Au172 are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.