Isomers in Tl-203 and core excitations built on a five-nucleon-hole structure

Isomers with three- and five-nucleon-hole configurations have been established in 203Tl. These include newly identified levels with a three-nucleon-hole structure: Ig = (15/2???) with T1/2 = 7.9(5) ns and Ig = (35/2???) with T1/2 = 4.0(5) ns. In addition, five-nucleon-hole states have also been established: Ig = (39/2???) with T1/2 = 1.9(2) ns and Ig = (49/2+) with T1/2 = 3.4(4) ns. The previously determined long-lived decay, T1/2 = 6.6(3) ??s from this work, is associated with isomerism of the Ig = (29/2+) state. Levels above this long-lived isomer have been identified through a delayed-prompt ?? ??? ?? coincidence measurement. Five-nucleon-hole states with excitation energies Ex ??? 7 MeV have been established as well as possible octupole excitations of the 208Pb core built on these levels. The level scheme of 203Tl is extended up to Ex ??? 11 MeV with the inclusion of 25 new transitions. Empirical and shell-model calculations have been performed to aid in the description of the observed states which are found to be of intrinsic character.