Island of High-Spin Isomers nearN=82

Abstract

Experiments aimed at testing for the existence of yrast traps are reported. A search for delayed $\gamma$ radiation of lifetimes longer than ∼ 10 ns and of high multiplicity has been performed by producing more than 100 compound nuclei between Ba and Pb in bombardments with ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$, and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$ projectiles. An island of high-spin isomers is found to exist in the region $64\lesssim Z\lesssim 71$ and $N\lesssim 82$.