High-spin gamma -ray spectroscopy in Z=83 isotopes: 199,201Bi.

Abstract

The properties of high-spin states in $^{199}$,201Bi have been studied with the $^{194}$,196Pt${(}^{10}$B,5n\ensuremath{\gamma} )${}^{199}$,201Bi reactions at energies between 57 and 72 MeV. In-beam measurements of \ensuremath{\gamma}-ray excitations, \ensuremath{\gamma}-\ensuremath{\gamma}-t coincidences and correlations, \ensuremath{\gamma}-ray angular distributions, and pulsed-beam-\ensuremath{\gamma} timing were performed with Ge detectors to determine level energies, decay schemes, \ensuremath{\gamma}-ray multipolarities, ${J}^{\ensuremath{\pi}}$ assignments, and isomeric lifetimes. Levels along and near the yrast lines were established up to J\ensuremath{\approxeq}(33/2), including a number of isomers. The systematic trends of three-quasiparticle level energies in odd-mass Bi isotopes have been extended and compared with calculations involving neutron-hole configurations of the Pb-core isotones. The transition strengths extracted for $^{199}$,201Bi are compared to Pb-region values. In addition, an isomeric lifetime was measured in $^{200}\mathrm{Bi}$.