Sensitivity of neutrino mass experiments to the cosmic neutrino background

Abstract

The KATRIN neutrino experiment is a next-generation tritium beta decay experiment aimed at measuring the mass of the electron neutrino to better than 200 meV at 90% C.L. Because of its intense tritium source, KATRIN can also serve as a possible target for the process of neutrino capture, νe+[superscript H-->[superscript 3]He++e-. The latter process, possessing no energy threshold, is sensitive to the cosmic neutrino background (CνB). In this paper, we explore the potential sensitivity of the KATRIN experiment to the relic neutrino density. The KATRIN experiment is sensitive to a CνB overdensity ratio of 2.0×10[superscript 9] over standard concordance model predictions (at 90% C.L.), addressing the validity of certain speculative cosmological models.