A. Huber

Sensitivity of Next-Generation Tritium Beta-Decay Experiments for keV-Scale Sterile Neutrinos

We investigate the sensitivity of tritium β-decay experiments for keV-scale sterile neutrinos. Relic sterile neutrinos in the keV mass range can contribute both to the cold and warm dark matter content of the universe. This work shows that a large-scale tritium beta-decay experiment, similar to the KATRIN experiment that is under construction, can reach a statistical sensitivity of the active-sterile neutrino mixing of sin2θ ~ 10−8. The effect of uncertainties in the known theoretical corrections to the tritium β-decay spectrum were investigated, and found not to affect the sensitivity significantly. It is demonstrated that controlling uncorrelated systematic effects will be one of the main challenges in such an experiment.

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

Abstract ADC non-linearities are a major systematic effect in the search for keV-scale sterile neutrinos with tritium β -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 β -decay spectrum to a level of ppm . The best results are achieved with a multi-pixel ( ≥ 10 4 pixels) detector using full waveform digitization. In this case, active-to-sterile mixing angles of the order of sin 2 θ = 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 ≥ 10 5 .