High-spin states and isomers in the one-proton-hole and three-neutron-hole 204Tl isotope

The high-spin structure of the neutron-rich Tl-204 isotope has been studied up to a 11.2-MeV excitation energy and a I = 30 spin range using the deep-inelastic heavy-ion gamma-spectroscopy method with reactions of Ca-48 on thick Pb-208 and U-238 targets. The established structure of yrast levels involves four isomeric states up to I-pi = 22(-), the highest spin state available for the maximally aligned four valence holes. The observations are interpreted and quantitatively confirmed by shell-model calculations. The rates of the identified M2 and E3 isomeric decays are discussed and a striking analogy is found for the yrast level structures and gamma decays observed in the 18(+) to 22(-) and 45/2(-) to 53/2(+) spin ranges in Tl-204 and Hg-203, respectively. In the highest spin part of the scheme, two prominently populated yrast states are tentatively identified as the 3-Pb-208 core excitation built on the 22(-) and 20(+) maximally aligned four-hole states. Their energies are reproduced well by using energy shifts observed in experiments for the Pb-208 core octupole excitation coupled to simpler intrinsic structures.