Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 40: Theorie VI

HK 40.5: Talk

Thursday, March 20, 2003, 14:30–14:45, D

Effects of deformation in double beta decay calculations — •Larisa Pacearescu — Inst.für Theoretische Physik, Auf der Morgenstelle, 72076-Tübingen

The aim of this work is to study the role of deformation, residual interaction, pairing and QRPA corelations on the Gamov-Teller strength distribution and 2νββ matrix elements, how well the half-life is reproduced in the framework of deformed nuclei. In all calculations, performed up to now for Ge and Mo, time-reversal and axial symmetry are assumed. The mean field is described by a axially deformed Wood-Saxon potential. The single particle wave functions are expanded in terms of the eigenstates of an axially symmetric harmonic oscillator in cylindrical coordinates. The method includes pairing between like nucleons in the BCS approximation with fixed gaps for protons and neutrons. The residual interaction for charge-exchange channel including particle-hole and particle-particle terms, is treated in the RPA approximation. The strength of the residual interaction (particle-hole and particle-particle) is given by a mass formula. We get a good agreement between the calculated and experimental energy of the giant Gamov-Teller resonance for Ge, Se, Mo, and Ru nuclei. To check our model accuracy we performed the calculations for spherical limit as well and we compare with the known results for spherical models. The role of deformation is rather important for beta strength which looks quite different comparing with the spherical case. Also the 2νββ matrix elements are supressed, the experimental half-life is reproduced and the collapse comes later.