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 Tl203. These include newly identified levels with a three-nucleon-hole structure: Iπ = (15/2-) with T1/2 = 7.9(5) ns and Iπ = (35/2-) with T1/2 = 4.0(5) ns. In addition, five-nucleon-hole states have also been established: Iπ = (39/2-) with T1/2 = 1.9(2) ns and Iπ = (49/2+) with T1/2 = 3.4(4) ns. The previously determined long-lived decay, T1/2 = 6.6(3) μs from this work, is associated with isomerism of the Iπ = (29/2+) state. Levels above this long-lived isomer have been identified through a delayed-prompt γ-γ coincidence measurement. Five-nucleon-hole states with excitation energies Ex≈ 7 MeV have been established as well as possible octupole excitations of the Pb208 core built on these levels. The level scheme of Tl203 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

Metastable states from multinucleon excitations in Tl 202 and Pb 203

The excited level structures of Tl202 and Pb203, above the 7+ and 29/2- isomers, respectively, have been studied. An isomer with Iπ=20+ and T1/2=215(10)μs has been established in Tl202, and the level scheme extended from I=10 to 20ℏ with the placement of fifteen new transitions. In Pb203, the Iπ=37/2+ state is established to be metastable, with T1/2=2.5(3)ns. Levels in both nuclei arise from intrinsic excitations, with likely particle-hole character for the higher-lying states in Pb203. The 20+ isomer in Tl202 is most likely associated with a πh11/2-1 - ν(i13/2-2,f5/2-1) configuration, while the 37/2+ state in Pb203 results from the excitation of five neutrons. Calculations, using both an empirical approach and the oxbash code, have been performed to aid in the description of the excited level structure