In this work a review on neutrino physics in the standard model and its extensions for
massive neutrinos is given. The differences of Dirac- and Majorana-Neutrinos is discussed
and further topics like neutrino oscillation, see-saw-mechanism and neutrinoless double
beta-decay (0-decay) are mentioned.
A method is presented which will allow to experimentally check and disfavour some nuclear
matrix elements (NME). It is based on the half-life ratio RN1
N2 = T1/2(N1) / T1/2(N2).
The more half-lifes one compares, the more likely one will be able to choose a single NME.
Besides it will be possible to investigate the effect of quenching the axial-vector-coupling
gA in 0-decay, if at least three half-lifes are determined. Finally the method is examined
in case that some alternative mechanisms contribute to the transition amplitude.