keV-Scale Sterile Neutrino Sensitivity Estimation with Time-Of-Flight Spectroscopy in KATRIN using Self-Consistent Approximate Monte Carlo

TL;DR

This paper explores using time-of-flight spectroscopy in KATRIN to improve sensitivity to keV-scale sterile neutrinos, introducing a new analysis method and assessing potential hardware implementations to enhance dark matter detection capabilities.

Contribution

The study proposes a novel TOF mode and the self-consistent approximate Monte Carlo method for sensitivity estimation, demonstrating potential improvements over standard approaches.

Findings

TOF mode could improve sensitivity to sin^2θ by a factor of two.

Self-consistent approximate Monte Carlo method effectively estimates sensitivity.

Gated filtering offers hardware implementation with reduced signal rate.

Abstract

We investigate the sensitivity of the Karlsruhe Tritium Neutrino Experiment (KATRIN) to keV-scale sterile neutrinos, which are promising dark matter candidates. Since the active-sterile mixing would lead to a second component in the tritium $\beta$-spectrum with a weak relative intensity of order $\sin^2\theta \lesssim 1\times10^{-6}$, additional experimental strategies are required to extract this small signature and to eliminate systematics. A possible strategy is to run the experiment in an alternative time-of-flight (TOF) mode, yielding differential TOF spectra in contrast to the integrating standard mode. In order to estimate the sensitivity from a reduced sample size, a new analysis method, called self-consistent approximate Monte Carlo (SCAMC), has been developed. The simulations show that an ideal TOF mode would be able to achieve a statistical sensitivity of $\sin^2\theta \sim 5\times10^{-9}$ at one $\sigma$, improving the standard mode by approximately a factor two. This relative benefit grows significantly if additional exemplary systematics are considered. A possible implementation of the TOF mode with existing hardware, called gated filtering, is investigated, which, however, comes at the price of a reduced average signal rate.