Searches for a sterile-neutrino admixture in detecting tritium decays in a proportional counter: New possibilities

• Published in: Physics of atomic nuclei 2015-03, Vol.78 (2), p.268-280
• Main Authors: Abdurashitov, D. N., Berlev, A. I., Likhovid, N. A., Lokhov, A. V., Tkachev, I. I., Yants, V. E.
• Format: Article
• Language: English
• Subjects: DATA ACQUISITION; Detectors; ELECTRONS; Elementary Particles and Fields; ENERGY RESOLUTION; ENERGY SPECTRA; KEV RANGE; NEUTRINOS; NUCLEAR DECAY; Particle and Nuclear Physics; PARTICLE IDENTIFICATION; Physics; Physics and Astronomy; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; PROPORTIONAL COUNTERS; Radiation, Background; READOUT SYSTEMS; TRITIUM
• ISSN: 1063-7788; 1562-692X
• DOI: 10.1134/S1063778815020027

An experiment aimed at searches for an admixture of a sterile neutrino whosemass is 1 to 8 keV via detecting electrons from tritium decay in a proportional counter is proposed. The admixture in question can be discovered by a specific distortion of the energy spectrum of these electrons. For the above masses, the distortion extends over the whole spectrum; therefore, use can bemade of detectors that have a relatively low energy resolution (about 10 to 15%). A classic proportional counter is a simple and natural choice of detector for the decays of a gaseous tritium. The approach that we propose is novel in two respects. On one hand, the proportional counter used is made as a discrete unit in the form of a fully fused quartz tube. This permits a readout of current signals directly from the anode filament and ensures a high stability in the case of long-term measurements. At the same time, the application of state-of-the-art digital data-acquisition methods will make it possible to perform measurements under conditions of high counting rates—up to 10 6 Hz. As a result, the energy spectrum of electrons from tritium decays that is formed by 10 12 counts could be accumulated within about a month. This data sample would make it possible to set an upper limit in the range of 10 −3 –10 −5 on a sterile-neutrino admixture at a confidence level of three standard deviations (3 σ ) for m s in the range of 1–8 keV, this being one to two orders of magnitude more stringent than present-day limits.