Relative Excitations of thePu237Shape Isomers

Abstract

The excitation energy of the 1120-nsec spontaneous-fission isomer of ${}_{}{}^{237}{}_{}{}^{}\mathrm{Pu}$ has been shown to be 0.30 ± 0.15 MeV above that of the 82-nsec isomer. The half-life of the longer-lived isomer may therefore be determined by its radiation width rather than by its direct fission width.