Yrast excitations in the neutron-rich N=52 isotones

The Kr-88 nucleus has been reinvestigated with prompt-gamma-ray-spectroscopy methods using the Gammasphere Ge array to measure gamma rays following spontaneous fission of Cf-252. 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 Kr-88. These data, together with the shell-model calculations, explained the near-yrast structure of Kr-88, which is similar to the structure of the N = 52, Sr-90, and Zr-92 isotones. The regular systematics obtained for the three isotones suggests that the spin of the 2073.4-keV level in the Se-86 isotone is different from the I = 6 value reported previously. Using data from prompt gamma-ray measurement of spontaneous fission of Cm-248, we reinvestigated the 86Se nucleus. A new candidate for the 6(1)(+) level in Se-86 has been proposed, which is supported by shell-model calculations. Energies of the 2(1)(+) and 4(1)(+) levels in the Zn-82 nucleus have been predicted using a novel systematics.