Detailed spectroscopy ofBi193

Abstract

An experiment aiming to study shape coexistence in $^{193}\mathrm{Bi}$ has been performed. Due to its transitional character, it has an exceptionally large number of structures identified close to the yrast line. Many new states have been found, significantly extending the previously known level scheme of $^{193}\mathrm{Bi}$, including several new rotational bands. The $\ensuremath{\pi}{i}_{13/2}$ band was extended to ${I}^{\ensuremath{\pi}}=45/{2}^{+}$. The ${I}^{\ensuremath{\pi}}=31/{2}^{+}$ member of the $\ensuremath{\pi}{i}_{13/2}$ band was found to de-excite also to a long-lived isomeric state. This isomeric state is located at 2350 keV and has a spin and parity of $29/{2}^{+}$. The half-life of the isomeric state was measured to be 85(3) $\ensuremath{\mu}\mathrm{s}$ and it decays via the emission of an 84 keV $E2$ transition. A level structure feeding this isomeric state was constructed. A low-energy, 49 keV transition has been identified to depopulate the ($29/{2}^{\ensuremath{-}}$) isomeric state, which places it at an energy 2405 keV in the level scheme. This is the first time such a decay has been observed in the neutron-deficient Bi isotopes. A superdeformed band almost identical to that present in the neighboring isotope $^{191}\mathrm{Bi}$, based on the 1/2[651] Nilsson orbital, has also been identified.