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

Abstract

Isomers with three- and five-nucleon-hole configurations have been established in ${}^{203}$Tl. These include newly identified levels with a three-nucleon structure: {\it I}${}^{\pi }$ = (15/2${}^{-}$) with {\it T}${}_{1/2}$ = 7.9(5) ns, and {\it I}${}^{\pi }$ = (35/2${}^{-}$) with {\it T}${}_{1/2}$ = 4.0(5) ns. In addition, five-quasiparticle states: {\it I}${}^{\pi }$ = (39/2${}^{-}$) with {\it T}${}_{1/2}$ = 1.9(2) ns, and {\it I}${}^{\pi }$ = (49/2${}^{+}$) with {\it T}${}_{1/2}$ = 3.4(4) ns have also been established. The previously determined long-lived decay [{\it T}${}_{1/2}$ = 6.6(3) $\mu$s from this work] is associated with isomerism of the {\it I}${}^{\pi }$ = (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 {\it E}${}_x$ $\approx$ 7 MeV have been established as well as possible octupole excitations of the ${}^{208}$Pb core built on these levels. The level scheme of ${}^{203}$Tl is extended up to {\it E}${}_x$ $\approx$ 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 predominantly of intrinsic character.

14 pages, 10 figures

Cited by in corpus (2)

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