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The decays of mass-separated Kr and Rb have been studied using y-ray singles and coincidence techniques. From the decay of Kr, a level scheme is proposed for Rb consisting of 60 excited states and accommodating 218 of the 220 observed transitions. The halflife of the 108.8-keV level of 9 Rb has been determined to be 0.8 + 0.3 nsec by delayed coincidence techniques. From the decay of~Rb, 109 of the 125 observed transitions are placed in a level. scheme for 9~Sr containing 37 excited states. The half-life of the 93.6-keV level in 9 Sr has been measured to be 8?.5+3.0 nsec. Ground-state p branching has been determined to be (10 +4) /& and (5 + 5)~/ p for the decays of Kr and 9 Rb, respectively, Some spin-parity assignments are made, and a shell-model interpretation is suggested for some of the levels. RADIOACTIVITYKr, Rb [from~U(n J)]; measured E&, I&, y-y coin, delayed coin, deduced g.s. P branch, logft. 9 Rb, 9 Sr deduced levels, J, 7t, T&&2. Mass-separatedKr activity. sented which contained 18 levels to accommodate 28 transitions. The recent work of Achterberg et al. ' presents a level scheme of 16 levels and 39 transitions.The work on these decays at the TRISTAN facility has proceeded from a variety of measurements.The half-lives of "Kr and "Rb were first determined to be 8.57+ 0.04 sec and 58.2+ 0.2 sec, respectively. " The decay energies were measured by P-y coincidence techniques to be 6.12+ 0.07 MeV and 5.68+ 0.04 MeV, respectively. " Finally, while this work was in its final stages, the internal conversion coefficients for the dominant lowenergy transitions in both decays were measured 13 1630

The P and subsequent y decays of ' Kr have been studied using an on-line isotope separator system. Ge(Li) y-ray singles and y-y coincidence measurements were used to construct the level scheme for Rb. This scheme has 31 excited states and includes 96 of the 103 observed y-ray transitions. Spin and parity assignments have been deduced using P-decay logft values from y-ray intensity balances and internal conversion coefficients determined by on-line magnetic spectrometer measurements. Interpretation of some energy levels is made from a shell-model viewpoint. HADIOACTIVITYKr from U(n, f); measured E and I for y, ce; p-y coin.Ge(Li) detectors. Magnetic spectrometer.Hb deduced ICC, multipolarities, levels, J', 7t, logft. Mass-separated Kr activity.

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