Characterization of two-quasiparticle levels in the odd–odd nucleus²⁵²Es

Abstract

Bandhead energies of the low-lying two-quasiparticle (2qp) structures in the doubly odd nucleus 252Es are evaluated using a phenomenological rotor-particle model with the inclusion of residual interaction contributions. The results are compared with the experimental data from 256Md α-decay to deduce configuration assignments for the observed 252Es levels and to place the γ's seen in the α–γ coincidence experiments in this level scheme. The 252Es ground state is characterized as the 4+[7/2+[633]p ⊗ 1/2+[620]n] bandhead, consistent with all the known experimental data.

Level structures inNp240

“…This formulation has been effectively employed to describe, and to predict, the location and character of 2qp bands, in particular the frequently occurring long-lived isomer pairs of several odd-odd actinides ranging from 93 Np through 101 Md [20][21][22][23][24][25][26][27]. Exhaustive data on 2qp bands and associated rotational levels of the actinides [16] and the rare-earth nuclei [28,29] have since been presented in a series of review articles, wherein a semiempirical version of the earlier formulation is introduced.…”