Search for sterile neutrinos at reactors

TL;DR

This paper investigates the potential to detect sterile neutrinos at very short baseline reactor experiments, highlighting limitations with conventional reactors and promising sensitivity with small fast neutron reactors like Joyo.

Contribution

It demonstrates that small fast neutron reactors can achieve high sensitivity to sterile neutrino mixing, overcoming limitations of conventional reactor setups.

Findings

Sensitivity is lost for Δm² > 1 eV² in conventional reactors due to core size smearing.

Fast neutron reactors like Joyo can reach sensitivity as good as 0.03 in sin²2θ₁₄ for several eV².

Small reactor size enhances the potential to detect sterile neutrino mixing.

Abstract

The sensitivity to the sterile neutrino mixing at very short baseline reactor neutrino experiments is investigated. In the case of conventional (thermal neutron) reactors it is found that the sensitivity is lost for $\Delta m^2 \gtrsim$ 1 eV$^2$ due to smearing of the reactor core size. On the other hand, in the case of an experimental fast neutron reactor Joyo, because of its small size, sensitivity to $\sin^22\theta_{14}$ can be as good as 0.03 for $\Delta m^2 \sim$ several eV$^2$ with the Bugey-like detector setup.