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New results for the two neutrino double beta decay in deformed nuclei with angular momentum projected basis

A. A. Raduta·A. Escuderos·A. Faessler·E. Moya de Guerra·P. Sarriguren
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Abstract

Four nuclei which are proved to be $2νββ$ emitters ($^{76}$Ge, $^{82}$Se, $^{150}$Nd, $^{238}$U), and four suspected, due to the corresponding Q-values, to have this property ($^{148}$Nd, $^{154}$Sm, $^{160}$Gd, $^{232}$Th), were treated within a proton-neutron quasiparticle random phase approximation (pnQRPA) with a projected spherical single particle basis. The advantage of the present procedure over the ones using a deformed Woods Saxon or Nilsson single particle basis is that the actual pnQRPA states have a definite angular momentum while all the others provide states having only K as a good quantum number. The model Hamiltonian involves a mean field term yielding the projected single particle states, a pairing interaction for alike nucleons and a dipole-dipole proton-neutron interaction in both the particle-hole (ph) and particle-particle (pp) channels. The effect of nuclear deformation on the single beta strength distribution as well as on the double beta Gamow-Teller transition amplitude (M$_{\rm GT}$) is analyzed. The results are compared with the existent data and with the results from a different approach, in terms of the process half life T$_{1/2}$. The case of different deformations for mother and daughter nuclei is also presented.

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A. A. Raduta, A. Escuderos, A. Faessler, E. Moya de Guerra, P. Sarriguren. 2004-07-20. New results for the two neutrino double beta decay in deformed nuclei with angular momentum projected basis. https://doi.org/10.1103/physrevc.69.064321

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