Eur. Phys. J. A (2022) 58: 6
https://doi.org/10.1140/epja/s10050-021-00657-8

Regular Article - Experimental Physics

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

¹ JCLab, IN2P3-CNRS, Université Paris Saclay, 91405, Orsay, France
² FLNR, JINR, Dubna, Russia
³ Dubna State University, Dubna, Russia
⁴ The Institute of Nuclear Physics, 050032, Almaty, Republic of Kazakhstan
⁵ CNRS, IPHC UMR 7178, Université de Strasbourg, 67000, Strasbourg, France
⁶ GANIL, 14076, Caen Cedex 5, France
⁷ Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, 84248, Bratislava, Slovakia

^a karl.hauschild@cnrs.fr

Received: 5 July 2021
Accepted: 22 December 2021
Published online: 18 January 2022

Abstract

The decay properties of states in ${}^{257}$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 from a low-lying isomeric state in ${}^{257}$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. Due to the favoured nature of the $\alpha$-decay the 11/2${}^{-}$[725] Nilsson configuration is also assigned to the first excited state of ${}^{257}$Rf, lying at 74 keV.