Collective rotations of fission isomers in actinide nuclei

Abstract

Using the total-Routhian-surface (TRS) method, the rotational behaviors of fission isomers in the second well of actinide nuclei 234–242U, 236–244Pu and 238–246Cm were investigated. The pairing-deformation-frequency self-consistent TRS calculations reproduced reasonably the experimental moments of inertia extracted from spectroscopic data. It is calculated that, in these largelyelongated (β2 ≈ 0.65 and β4 ≈ 0.03) fission isomers, the \(v\tfrac{1} {2}^ - [981]\) neutron and \(\pi \tfrac{1} {2}^ + [651]\) proton align simultaneously at rotational frequency ħω ≈ 0.4–0.6 MeV (corresponding to spin I ≈ 80ħ), which leads to clear upbending in moments of inertia (MoI’s). Our calculations have indicated that the hexadecapole deformation β4 influenced significantly the frequency of the rotational alignment of the proton \(\tfrac{1} {2}^ + [651]\) orbit.