Metastable States of Se92,94 : Identification of an Oblate K Isomer of

C. Lizarazo¹,

P.-A. Söderström²,

V. Werner³

et al.

Gamma-ray spectroscopy of fission fragments with state-of-the-art techniques

“…The 94 Kr isomer has a two-quasineutron structure with dominant configuration ν(h 11/2 g 7/2 ) and oblate deformation β = -0,22 [165], very similar to that of the neighboring isotones 92 Se and 96 Sr, observed in relativistic fission of 238 U and spontaneous fission of 248 Cm, respectively (see Fig. 22) [170,171]. Such data allow testing the single-particle energies in the region of 78 Ni, in particular for what concerns the position of the νh 11/2 orbital, which is not fully established, experimentally.…”

“…The analysis of its decay pattern shows a highly K-forbidden E1 transition, in line with what observed for multi-qp high-K isomers reported in the A =160-190 region, as well as from quasi-continuum studies performed with the AGATA array in 174 W [196], thus supporting the important role of the level density in the determination of K-forbidden transition. At RIKEN, isomeric states were also observed in the N = 100 isotones of 162 Sm, 163 Eu and 164 Gd (with K π = 4 − ) [197,198], in the N = 102 isotones of 166 Gd and 164 Sm (with K π = 6 − ) [199], in 168,169,170,172 Dy (with K π = 4 − , 1/2 − , 6 − and 8 − ) [200][201][202], and in 158,160 Nd with (4 − ) and (6 − ) assignments [192]. The detailed investigation of the structure of such systems has also significant impact on the understanding of the element abundances at the A∼160, which is believed to arise from a strong deformed shell closure, around N = 100 [203].…”