Anomalous Structure in the Beta Decay of Gaseous Molecular Tritium

Abstract

We have made high statistics measurements of tritium beta decay to set a limit on the mass of the electron antineutrino.The measurements used a windowless gaseous source of molecular tritium and a high resolution toroidal field magnetic spectrometer. We calibrate the system using conversion electrons from the decay of Kr. The best fit value for the neutrino mass squared is significantlynegative. An anomalous structure in the beta decay spectrum in the last 55 eV closest to the end point causes this result.A direct measurement of neutrino mass can be made by studying the beta decay of tritium as a massive electron antineutrino will alter the shape of this lowenergy beta decay spectrum. In 1980 Lubimov and coworkers [1] reported evidence for a 30-eV neutrino mass in their studies of the beta decay of tritium implanted in valine. Subsequent attempts by groups in Tokyo [2] and Zurich [3], who implanted tritium in thin films, found no evidence for this mass. These groups were able to

Tachyonic field theory and neutrino mass running

“…(12) and (13) below]. These observations are inconsistent with beta decay end point measurements [6][7][8][9][10][11][12] which have led to values of a few eV 2 , for neutrinos in the keV energy range. This confusing situation raises a number of questions.…”

“…which is at least six orders of magnitude larger than the neutrino masses at low energy [6][7][8][9][10][11][12]. Likewise, assuming the dispersion relation (3) implies that…”

“…Otherwise, it seems that the high-energy OPERA data [5] (in the GeV range) cannot be reconciled with the low-energy experimental results (in the keV range) of Refs. [6][7][8][9][10][11][12]. Of course, this statement holds provided the OPERA data are not subject to a hitherto undiscovered systematic error.…”

“…One of the prime candidates for a genuinely superluminal particle is the neutrino, which has never been observed at rest. A number of experimental groups have measured negative mass squares for the electron neutrino from tritium beta decay endpoints [6][7][8][9] with mean values in the interval −147 eV 2 < 2 ν < 0 for the electron neutrino mass square, at an energy of the order of E ν ≈ 18 keV. While some recent measurements indicate values consistent with a vanishing neutrino mass [10][11][12] at even lower energies, the mean value of the experimental data for 2 ν (electron neutrino) still is negative and of the order of a few negative eV 2 (for an excellent overview, see The Ultimate Neutrino Page 1 ).…”

Breakthrough propulsion physics workshop preliminary results

“…In addition, recent experiments of the rest mass of the electron antineutrino have measured an imaginary value (Stoeffl 1995 (Chiao 1996).…”