Impact of ADC non-linearities on the sensitivity to sterile keV neutrinos with a KATRIN-like experiment

TL;DR

This paper investigates how ADC non-linearities affect sterile neutrino searches in KATRIN-like experiments and demonstrates mitigation techniques, including multi-pixel detectors and waveform digitization, to improve sensitivity.

Contribution

It introduces effective methods to mitigate ADC non-linearities, enabling more precise sterile neutrino detection in tritium beta-decay experiments.

Findings

Multi-pixel detectors with waveform digitization reduce non-linearity effects to below 1 ppm.

Active-to-sterile mixing angles of about 10^{-7} are detectable with these techniques.

Linear ADCs or increased pixel counts can achieve similar sensitivities.

Abstract

ADC non-linearities are a major systematic effect in the search for keV-scale sterile neutrinos with tritium $\beta$-decay experiments like KATRIN. They can significantly distort the spectral shape and thereby obscure the tiny kink-like signature of a sterile neutrino. In this work we demonstrate various mitigation techniques to reduce the impact of ADC non-linearities on the tritium $\beta$-decay spectrum to a level of $<$ ppm. The best results are achieved with a multi-pixel ($\geq10^4$ pixels) detector using full waveform digitization. In this case, active-to-sterile mixing angles of the order of $\sin^2 \theta = 10^{-7}$ would be accessible from the viewpoint of ADC non-linearities. With purely peak-sensing ADCs a comparable sensitivity could be reached with highly linear ADCs, sufficient non-linearity corrections or by increasing the number of pixels to $\geq 10^5$.