Isospin symmetry and proton decay: Identification of the ${10}^{+}$ isomer in $^{54}\mathrm{Ni}$

Rapid Communication

Isospin symmetry and proton decay: Identification of the $10^{+}$ isomer in ${}^{54}{Ni}$

D. Rudolph et al.

Phys. Rev. C 78, 021301(R) – Published 6 August 2008

Abstract

The γ decays from an isomeric $10^{+}$ state at 6457 keV in the nucleus $_{28}^{54}$ ${Ni}_{26}$ have been identified using the GSI fragment separator in conjunction with the RISING Ge-detector array. The state is interpreted as the isobaric analog of the 6527-keV $10^{+}$ isomer in $_{26}^{54}$ ${Fe}_{28}$ . The results are discussed in terms of isospin-dependent shell-model calculations. Clear evidence is presented for a discrete $ℓ = 5$ proton decay branch into the first excited $9 / 2^{-}$ state of the daughter ${}^{53}{Co}$ . This decay is the first of its kind observed following projectile fragmentation reactions.