The decay of mass-separated ¹⁹³Pb to ¹⁹³Tl

Mass-separated samples of produced by ¹⁹³Pb and W(¹⁶O,xn) and Ta(²⁰ Ne,pxn) reactions were collected by the UNISOR isotope separator operating on-line to the Oak Ridge Isochronous Cyclotron. N-type germanium radiation detectors and a Si(Li) radiation detector were used to gather multiscaled gamma-ray and conversion electron singles data and gamma-gamma and gamma-conversion electron coincidence data. A decay scheme was deduced from these data.

The decay rate of the 13/2 ⁺isomer of ¹⁹³Pb was measured to be 5.65±0.07 minutes. Low spin states found in ¹⁹³Tl give evidence of a low-spin isomer of ¹⁹³Pb, but the half-life of 5.72±0.31 minutes found for it does not differ significantly from that of the high-spin isomer.

Shell-model states of s_1/2, d_3/2, and h_11/2 were observed and interpreted as proton hole states weakly coupled to a spherical ¹⁹⁴Pb core. Shell models of h_9/2 and i_13/2 were observed and interpreted as proton particle states strongly coupled to an oblate ₁₉₂Hg Core. The expected state due to a proton hole coupled to a proton two particle-two hole state in a ₁₉₄Pb core was searched for but not observed<.p>The experimental results were compared to the triaxial-rotor-plus-particle model of Meyer-ter-Vehn. The experimentally discovered members of the h_9/2 structure were found to be in excellent agreement with those predicted by this rigid triaxial rotor model.