Constraints on the Active and Sterile Neutrino Masses from Beta-Ray Spectra: Past, Present and Future1
Otokar Dragoun*, Drahoslav Vénos*
Identifiers and Pagination:Year: 2016
First Page: 73
Last Page: 113
Publisher Id: PHY-3-73
Article History:Received Date: 4/7/2015
Revision Received Date: 5/8/2015
Acceptance Date: 12/9/2015
Electronic publication date: 30/09/2016
Collection year: 2016
open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (https://creativecommons.org/licenses/by-nc/4.0/legalcode), which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.
Although neutrinos are probably the most abundant fermions of the universe their mass is not yet known. Oscillation experiments have proven that at least one of the neutrino mass states has mi > 0.05 eV while various interpretations of cosmological observations yielded an upper limit for the sum of neutrino masses ∑mi < (0.14 ‒ 1.7) eV. The searches for the yet unobserved 0νββ decay result in an effective neutrino mass mββ < (0.2 ‒ 0.7) eV. The analyses of measured tritium β-spectra provide an upper limit for the effective electron neutrino mass m(ve) < 2 eV. In this review, we summarize the experience of two generations of β-ray spectroscopists who improved the upper limit of m(ve) by three orders of magnitude. We describe important steps in the development of radioactive sources and electron spectrometers, and recapitulate the lessons from now-disproved claims for the neutrino mass of 30 eV and the 17 keV neutrino with an admixture larger than 0.03%. We also pay attention to new experimental approaches and searches for hypothetical sterile neutrinos.