Alpha-decay spectroscopy of ${}^{257}$Rf

Abstract

The decay properties of the ground state and excited states of ${}^{257}$Rf have been investigated with the detector array GABRIELA at the FLNR, Dubna. The electromagnetic decay of a new excited state in ${}^{253}$No has been observed. The state lies 750 keV above the ground state and is favourably populated in the alpha decay of the low-lying spin isomer of ${}^{257}$Rf. It decays to the 9/2${}^{-}$ ground state by an M1 transition and is assigned the 11/2${}^{-}$[725] Nilsson configuration. The presence of this state suggests a possible reinterpretation of the decay of the high-K isomer in ${}^{253}$No.

7 pages, 4 figures