Level schemes of /sup 91/Rb and /sup 91/Sr populated in beta decay

The decays of mass-separated /sup 91/Kr and /sup 91/Rb have been studied using ..gamma..-ray singles and coincidence techniques. From the decay of /sup 91/Kr, a level scheme is proposed for /sup 91/Rb consisting of 60 excited states and accommodating 218 of the 220 observed transitions. The half-life of the 108.8-keV level of /sup 91/Rb has been determined to be 0.8 +- 0.3 nsec by delayed coincidence techniques. From the decay of /sup 91/Rb, 109 of the 125 observed transitions are placed in a level scheme for /sup 91/Sr containing 37 excited states. The half-life of the 93.6-keV level in /sup 91/Sr has been measured to be 87.4 +- 3.0 nsec. Ground-state ..beta.. branching has been determined to be 10 +- 4% and 7 +- 5% for the decays of /sup 91/Kr and /sup 91/Rb, respectively. Some spin-parity assignments are made, and a shell-model interpretation is suggested for some of the levels. (AIP)