The current status of ``Troitsk nu-mass'' experiment in search for sterile neutrino

Abstract

We propose a new experiment to search for a sterile neutrino in a few keV mass range at the "Troitsk nu-mass" facility. The expected signature corresponds to a kink in the electron energy spectrum in tritium beta-decay. The new goal compared to our previous experiment will be precision spectrum measurements well below end point. The experimental installation consists of a windowless gaseous tritium source and a high resolution electromagnetic spectrometer. We estimate that the current bounds on the sterile neutrino mixing parameter can be improved by an order of magnitude in the mass range under 5 keV without major upgrade of the existing equipment. Upgrades of calibration, data acquisition and high voltage systems will allow to improve the bounds by another order of magnitude.

Processing of higher count rates in Troitsk nu-mass experiment

“…Troitsk nu-mass experiment detailed description as well as sterile neutrino program proposal could be found in [3]. The recent results for sterile neutrino with mass up to 1 keV are published in [4].…”

“…It was sufficient for count rates of about 100 Hz used when the spectrum endpoint was investigated in search for electron neutrino mass ( [1]). However, at count rates required to get sufficient statistics for sterile neutrino search (20 -40 kHz) even small deviations of estimated dead time could produce huge differences in count rate (see systematic uncertainties estimation in [7]). Furthermore, since dead time was determined by analog readout system, it could be precisely estimated only experimentally.…”

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

“…[4]. At the current level of accumulated statistics the most important sources of systematic uncertainties are: events under detection threshold and electronics dead time.…”

“…Sterile neutrinos can be searched for by looking for such small β-spectrum distortions. Troitsk nu-mass experiment, which had been designed for the active neutrino mass measurements, and where the strongest direct limit on it [2,3] has been obtained so far, is well suited for the above task [4]. Moreover, currently, it is the only installation in operation which is capable for the sterile neutrino searches in the keV mass range.…”

“…Detailed description of Troitsk nu-mass experiment, hardware, procedures and important systematic errors inherent to the spectrum measurements on this apparatus, can be found in Ref. [4].…”