UNIFIED DESCRIPTION OF THE 2-NU-BETA-BETA DECAY IN SPHERICAL AND DEFORMED-NUCLEI

The Gamow-Teller double-beta decay, with two neutrinos in the final st ate, is calculated within the QRPA approach. Higher-order corrections to the RPA result are studied within a boson expansion formalism. The specific feature of the present paper is that the single-particle basi s is obtained through angular-momentum projection from an orthogonal s et of deformed wave functions. The effect of deformation on the Gamow- Teller transition amplitude, as well as on the the single beta- and be ta+ strengths distribution is obtained. The Gamow-Teller amplitude is calculated for the transitions 0i+ --> 0f+ and 0i+ --> 2f+. The method is applied to the 2nubetabeta decay probability Se-82(34) to Kr-82(36 ).