ELECTROMAGNETIC TRANSITION STRENGTHS BETWEEN HIGH-SPIN STATES IN SR-79 AND SR-80

High spin states in Sr79 were populated via the reaction Mg58,2pn) at 80 and 85 MeV beam energy. Twelve lifetimes in the range from 0.5 to 150 ps and four lifetime limits were measured with Doppler-shift methods. By comparing lifetimes in 79,80,82Sr obtained with the recoil distance and Doppler-shift attenuation methods, the appropriate electronic stopping power of Sr ions recoiling in Ta was determined. In addition, lifetimes of yrast states in Sr80 and Rb79 were determined in the concurrent reactions Mg58,2p) and Mg58,3p). The I=2 E2 transition strengths and the E2/M1 mixing ratios of the I=1 transitions in Sr79 confirm the picture of extremely prolate deformed rotational bands (20.42), based on the [301](3/2- and [422](5/2+ Nilsson orbits. A reduction in B(E2) values is observed at the onset of (3qp) alignment. The band structure of Sr79 is discussed in terms of the cranked shell and the Woods-Saxon cranking model with pairing. © 1990 The American Physical Society.