Yrast excitations in the neutron-rich N = 52 isotones.

The 88Kr nucleus has been reinvestigated with prompt-y-ray-spectroscopy methods using the Gammasphere Ge array to measure y rays following spontaneous fission of 252 Cf. The order of some of the transitions, reported previously, has been changed and new levels were introduced. Angular correlation analysis allowed the assignment of spins to several levels in 88Kr. These data, together with the shell-model calculations, explained the near-yrast structure of 88Kr, which is similar to the structure of the N = 52, 90Sr, and 92Zr isotones. The regular systematics obtained for the three isotones suggests that the spin of the 2073.4-keV level in the 86Se isotone is different from the l = 6 value reported previously. Using data from prompt y-ray measurement of spontaneous fission of 248Cm, we reinvestigated the 86Se nucleus. A new candidate for the level in 86Se has been proposed, which is supported by shell-model calculations. Energies of the 21+ and 41+ levels in the 82Zn nucleus have been predicted using a novel systematics. [ABSTRACT FROM AUTHOR]