αdecay ofAt194

Abstract

Detailed $\ensuremath{\alpha}$-decay studies of the neutron-deficient isotope $^{194}\mathrm{At}$ have been performed in the complete fusion reaction $^{56}\mathrm{Fe}+^{141}\mathrm{Pr}\ensuremath{\rightarrow}^{194}\mathrm{At}+3n$ at the velocity filter SHIP. Two $\ensuremath{\alpha}$-decaying isomeric states with half-lives of ${T}_{1/2}(^{194}\mathrm{At}{}^{m1})=310(8)$ ms and ${T}_{1/2}(^{194}\mathrm{At}{}^{m2})=253(10)$ ms were identified in this nucleus. Their complex decays to the states in the daughter nucleus $^{190}\mathrm{Bi}$ are discussed in the article. We propose that similar to the case of the neighboring $^{191,192,193,195}\mathrm{At}$ isotopes, the oblate-deformed configurations based on the proton ${1/2}^{+}[440]$ and/or $7/2{}^{\ensuremath{-}}[514]$ Nilsson orbitals become important in $^{194}\mathrm{At}$. A new isomeric state with the half-life of 175(8) ns was observed in $^{190}\mathrm{Bi}$.