# First measeurements in search for keV-sterile neutrino in tritium beta-decay by Troitsk nu-mass experiment

## TL;DR

This paper reports the first measurements of the tritium beta-decay spectrum in the 16-18.6 keV range aimed at detecting heavy sterile neutrinos, setting new upper limits on their mixing with electron neutrinos.

## Contribution

First experimental search for keV-scale sterile neutrinos in tritium beta-decay spectrum with improved upper limits on mixing.

## Key findings

- Set new upper limits on neutrino mixing matrix element U^2_{e4}
- Improved existing limits by a factor of 2 to 5 in the 0.1-2 keV mass range
- Detected no significant spectral distortions indicative of sterile neutrinos

## Abstract

We present the first measurements of tritium beta-decay spectrum in the electron energy range 16-18.6 keV. The goal is to find distortions which may correspond to the presence of a heavy sterile neutrinos. A possible contribution of this kind would manifest itself as a kink in the spectrum with a similar shape but with end point shifted by the value of a heavy neutrino mass. We set a new upper limits to the neutrino mixing matrix element U^2_{e4} which improve existing limits by a factor from 2 to 5 in the mass range 0.1-2 keV.