6533b836fe1ef96bd12a080d

RESEARCH PRODUCT

Low-spin structure of85Se and theβnbranching of85As

subject

description

Fission fragments from neutron-induced fission of ${}^{235}$U produced at the high-flux reactor of the Institut Laue-Langevin, Grenoble, were separated with the Lohengrin separator to provide a beam of neutron-rich ${}^{85}\phantom{\rule{-0.16em}{0ex}}$As nuclei. The ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of ${}^{85}\phantom{\rule{-0.16em}{0ex}}$As to ${}^{85}$Se was studied using $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ and $\ensuremath{\beta}$-$\ensuremath{\gamma}$ coincidence techniques. ${}^{85}$Se was also studied using the prompt-$\ensuremath{\gamma}$ coincidence data from spontaneous fission of ${}^{248}$Cm and ${}^{252}$Cf measured with the Eurogam2 and Gammasphere Ge arrays, respectively. The combination of $\ensuremath{\beta}$ decay and prompt-$\ensuremath{\gamma}$ data enabled the determination of spins and parities of low-energy excited states in ${}^{85}$Se. There are new arguments supporting the $5/{2}^{\ensuremath{-}}$ assignment for the ground state of ${}^{85}\phantom{\rule{-0.16em}{0ex}}$As.