Search

The cross section σ(Eν) for solar-neutrino capture by the 76Ge nucleus is calculated. The effect of Gamow-Teller resonances on the rate of neutrino capture in the reaction 76Ge (ν, e−)76 As is studied. It is shown that the contribution of high-lying Gamow-Teller resonances to the charge-exchange strength function increases the rate of solar-neutrino capture by 25% to 50%, depending on the normalization method and on the inclusion of the quenching effect.

The results are presented from calculating capture cross section σ(Eν) of solar neutrinos by 76Ge nuclei. Experimental data on strength function S(E), obtained in the charge-exchange 76Ge(3He, t)76As reaction, are used in these calculations. The effect the resonance structure of strength function S(E) has on cross section σ(Eν) is examined. It is shown that the giant Gamow–Teller resonance alone makes a contribution of ~20%, and the contribution of lower-lying excitations in the continuous spectrum part is even larger. These contributions must be considered in calculations for background events in experiments on double beta decay of the GERDA (LEGEND) type.

The effect of the GT-resonance structure of charge-exchange strength function in the 76Ge(3He,t)76 As reaction on the solar neutrino capture cross section was examined. It is shown that accounting of GT-resonances increase solar neutrino capture rate more then 20%. Theoretical strength functions for 76Ge and 74Ge were calculated in accordance with the framework of the self-consistent theory of finite Fermi systems. This results could help to decompose experimental strength function and itemize some low-lying excitation states and pygmy resonances. Also we demonstrate significant role of quenching effect for cross section calculations. Accurate counting of neutrino capture rate could change estimations on background events index in experiments on double beta decay search (like LEGEND).