Neutrino rest mass nonzero

The results concerning the allowance for the / -source molecular structure (Kaplan et al., 1982,1983) were used in reduction of the new experimental data obtained by the ITEP group. Table I (Boris et al., 1983) shows the most probable values of the neutrino rest mass obtained by data reduction using the models of a bare nucleus, of a tritium atom, and of a real valine molecule. The reduction of the new experimental data within the bare-nucleus model did not lead to a nonzero rest mass of the neutrino. The allowance for the electron structure of valine gives mvc2 = 33 eV.2 Thus, the quantum chemical calculations proved to be a necessary step in the reduction of the data concerning the properties of an elementary particle. 

One might estimate the value of the neutrino rest mass by the changes in the /i spectrum. However, the direct measurements are not possible, since at the high-energy edge of the fi spectrum, where the effect of the nonzero mv is manifest, the intensity of the spectrum is very low and is well below the level of the apparatus noise. Such experiments require a highly sensitive technique and... 

The effect of electron excitations of the / source is comparable in magnitude with the expected value of the neutrino rest mass and is manifested in the region most sensitive to the nonzero mv. The allowance for the molecular structure of the / source in reduction of the experimental data of the ITEP group has led to the most probable value of the neutrino rest mass mv = 33 eV (Boris et al., 1983). 

The problem of the nonzero rest mass of neutrinos cannot be considered as solved at present. The results obtained by the ITEP group are under active... 

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