Nanosecond isomers in near-spherical142,143Pm

Abstract

In-beam measurements of nanosecond lifetimes have been undertaken for some of the excited states in near-spherical nuclei ${}^{142,143}\mathrm{Pm}$ using the pulsed-beam \ensuremath{\gamma} coincidence technique and the generalized centroid-shift method of analysis. The ${}^{133}\mathrm{Cs}{(}^{13}\mathrm{C},xn)$ reaction with a 60 MeV pulsed beam of ${}^{13}\mathrm{C}$ was used to populate the excited states in the respective nuclei. The measured mean lifetimes have been compared with corresponding single-particle estimates.