Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

An upper limit on electron antineutrino mass from Troitsk experiment

V. N. Aseev, A. I. Belesev, A. I. Berlev, E. V. Geraskin, A. A. Golubev, N. A. Likhovid, V. M. Lobashev, A. A. Nozik, V. S. Pantuev, V. I. Parfenov, A. K. Skasyrskaya, F. V. Tkachov, S. V. Zadorozhny

TL;DR

This paper presents a direct, model-independent constraint on the electron antineutrino mass from tritium beta decay via the Troitsk nu-mass setup. It reanalyzes the full 1994–2004 data set with stringent quality cuts and a quasioptimal weights fitting method, achieving improved precision over earlier analyses. The resulting estimate $m_{\nu}^2 = -0.67 \pm 2.53$ eV$^2$ yields upper limits $m_{\nu} < 2.2$ eV (sensitivity), $m_{\nu} < 2.12$ eV (Bayesian), and $m_{\nu} < 2.05$ eV (Feldman–Cousins), with no need for an endpoint structure in the spectrum. The findings provide competitive direct constraints on the absolute neutrino mass and reinforce consistency with other direct measurements, while noting the passing of a leading figure in the field.

Abstract

An electron antineutrino mass has been measured in tritium beta-decay in the "Troitsk nu-mass" experiment. The setup consists of a windowless gaseous tritium source and an electrostatic electron spectrometer. The whole data set acquired from 1994 to 2004 was reanalysed. A thorough selection of data with the reliable experimental conditions has been performed. We checked every known systematic effect and got the following experimental estimate for neutrino mass squared m_{nu}^{2}=-0.67+/- 2.53 {eV}^{2}. This gives an experimental upper sensitivity limit of m_{nu}<2.2 eV and upper limit estimates m_{nu}<2.12 eV, 95% C.L. for Bayesian statistics and m_{nu}<2.05 eV, 95% C.L. for the Feldman and Cousins approach.

An upper limit on electron antineutrino mass from Troitsk experiment

TL;DR

This paper presents a direct, model-independent constraint on the electron antineutrino mass from tritium beta decay via the Troitsk nu-mass setup. It reanalyzes the full 1994–2004 data set with stringent quality cuts and a quasioptimal weights fitting method, achieving improved precision over earlier analyses. The resulting estimate eV yields upper limits eV (sensitivity), eV (Bayesian), and eV (Feldman–Cousins), with no need for an endpoint structure in the spectrum. The findings provide competitive direct constraints on the absolute neutrino mass and reinforce consistency with other direct measurements, while noting the passing of a leading figure in the field.

Abstract

An electron antineutrino mass has been measured in tritium beta-decay in the "Troitsk nu-mass" experiment. The setup consists of a windowless gaseous tritium source and an electrostatic electron spectrometer. The whole data set acquired from 1994 to 2004 was reanalysed. A thorough selection of data with the reliable experimental conditions has been performed. We checked every known systematic effect and got the following experimental estimate for neutrino mass squared m_{nu}^{2}=-0.67+/- 2.53 {eV}^{2}. This gives an experimental upper sensitivity limit of m_{nu}<2.2 eV and upper limit estimates m_{nu}<2.12 eV, 95% C.L. for Bayesian statistics and m_{nu}<2.05 eV, 95% C.L. for the Feldman and Cousins approach.

Paper Structure

This paper contains 13 sections, 20 equations, 6 figures, 1 table.

Table of Contents

  1. Introduction
  2. Experimental setup and procedure of measurements
  3. Experimental Setup
  4. Procedure
  5. Data analysis
  6. Data selection and experimental corrections
  7. Method of quasioptimal weights
  8. Spectrum and corrections
  9. Summing-up files
  10. Systematic errors
  11. Results
  12. Conclusion
  13. Acknowledgments

Figures (6)

  • Figure 1: Diagram of the installation:1,2 -- vacuum volume; 3,4 -- electrostatic system; 5 -- ground electrode; 6-9 -- superconducting coils; 10 -- warm solenoid; 11 -- Nitrogen shield; 12 -- Si(Li) detector; 13 -- emergency valve; 14 -- magneto-discharge pump; 15,16 -- mercury diffusion pumps; 17 -- tritium purification system; 18 -- electron gun; 19 -- argon trap.
  • Figure 2: Final states spectrum in molecule T$^3$He states. Every bin is a summand in eq. \ref{['eq:states']}.
  • Figure 3: The shape of the electron energy loss spectrum in tritium resolution. Different curves correspond to electron single, double, and triple scattering.
  • Figure 4: Integrated spectrum from the electron gun versus the applied potential on the spectrometer electrode. The WGTS pipe is filled with tritium. The voltage on the electron gun cathode is around 18800 V.
  • Figure 5: Energy loss spectrum, $\varepsilon=E_{in}-E_{fin}$, for electrons which were trapped in WGTS but after scattering reached the spectrometer. The bin size is 10 eV. The solid line is the analytic approximation of the losses.
  • ...and 1 more figures