Roles of triaxiality and residual interaction in signature inversions of A~130 odd-odd nuclei

摘要

Rotational bands with (neutron h_11/2)^1 (proton h_11/2)^1 configurations arestudied using a particle-rotor model in which a proton and a neutronquasiparticles interacting through a zero-range force are coupled with atriaxial rotor. It is shown for 124Cs that one can reproduce the signaturedependence of energy and B(M1)/B(E2) ratio best when one takes into accountgamma-deformations with irrotational-flow moment of inertia in addition to theproton-neutron interaction proposed by Semmes and Ragnarsson. Including botheffects, a systematic calculation of signature splittings is performed for Cs,La isotopes and N=75 isotones to be compared with experiments. Discussions arealso done on the deficiencies of the cranking model concerning itsapplicability to signature inversion phenomena in odd-odd nuclei.