Limits on neutrino masses from the tritium beta spectrum

Abstract

The beta spectrum of tritium has been studied with a pi square root (13)/2-spectrometer. The source consisted of tritium in the atomic form embedded in a metal-dioxide lattice. The measured spectrum was analysed down to 14 keV. All fitting parameters used, in addition to the mass parameter mnu , could be checked by independently determined physical values. No evidence for a non-vanishing antineutrino mass or a mixed state with a heavy antineutrino admixture in the mass region from 0.010 to 4 keV/c2 was found. Typical upper limits for the amplitude were 1.8*10-3 for a 3 keV/c2 and 16*10-3 for a 0.6 keV/c2 heavy neutrino branch at 95% confidence. The value of the electron antineutrino mass was determined to be mnu =15-15+32 eV/c2. The mass difference Delta M(3H-3He) was found to be 18597+or-14 eV/c2. Experimental effects influencing the determination of the rest mass are discussed and considered in the results.

Limits on the Existence of Heavy Neutrinos in the Range 50–1000 eV from the Study of the187ReBeta Decay

“…3. The existing previous limits obtained by studying the 3 H beta decay by Hiddeman et al [3] and Simpson [4] are also reported in the figure for comparison. Limits of 9 3 10 23 at 1000 eV͞c 2 , 1.2 3 10 22 at 500 eV͞c 2 , 4.4 3 10 22 at 200 eV͞c 2 , and 0.116 at 100 eV͞c 2 at 95% C.L.…”

“…1) [10,11]. The low end-point energy of the 187 Re decay (2470 6 5 eV [11]) and the good performances of the detector, especially in terms of energy resolution and detector response, allow significantly improved limits on the mixing angle of heavy mass neutrino in the mass interval between 50 and 1000 eV, which has been rarely investigated before [3,4].The calorimetric experiment measures not only the beta energy, but all the detectable energy released in the process (the electron energy and the excitation energy of the residual system) provided that the energy is fully thermalized. The measured spectrum is therefore well suited for neutrino mass investigations because it is complementary to the neutrino energy spectrum and is unaffected by the final state distribution or by secondary interactions of emitted electrons.…”

“…1) [10,11]. The low end-point energy of the 187 Re decay (2470 6 5 eV [11]) and the good performances of the detector, especially in terms of energy resolution and detector response, allow significantly improved limits on the mixing angle of heavy mass neutrino in the mass interval between 50 and 1000 eV, which has been rarely investigated before [3,4].…”

“…1 MeV, beta decay experiments searching for kinks in the energy spectra of the emitted electron are most sensitive. Experiments of this kind have been performed on 3 H, 35 S, 63 Ni, and 64 Cu [2][3][4][5][6][7][8][9]. We report here the results of such a search made studying the beta decay spectrum of 187 Re obtained with a cryogenic microcalorimeter.…”

First measurements in search for keV sterile neutrino in tritium beta-decay in the Troitsk nu-mass experiment

“…4 as a function of sterile neutrino mass. In the same figure we also present the existing published limits [7][8][9][10][11]. at 95% confidence level.…”