Neutrino mass measurements with KATRIN and beyond

• Caroline Rodenbeck (Karlsruhe Institute of Technology (KIT), Institute for Astroparticle Physics (IAP), Tritium Laboratory Karlsruhe (TLK))

Room: SR 4 The neutrino mass is one of the still-to-be-solved puzzles of particle physics. It is possible to measure the neutrino mass in a model-independent way using the kinematics of single beta decay, as pursued by the Karlsruhe Tritium Neutrino (KATRIN) experiment. At KATRIN, beta-decay electrons from the windowless gaseous tritium source are guided magnetically through the transport and pumping section to the spectrometer and detector section. At the spectrometer, the electrons’ momenta are collimated magnetically, and an electric field acts on them as a high-pass filter, only allowing electrons with enough kinetic energy to be guided to the detector where they are counted. This combination of a high-luminosity source with a precision integrating spectrometer allows for spectroscopy of the tritium beta-decay spectrum in its endpoint region where the impact of the neutrino mass on the spectral shape is strongest. KATRIN sets the presently most stringent upper limit on the neutrino mass obtained by direct measure- ments of 0.8 eV/c2. Currently, the KATRIN experiment is running to increase statistics and aims to reach a sensitivity below 0.3 eV/c2. Ultimately, determining the neutrino mass may require constructing experiments with sensitivities as low as the lower boundaries obtained by neutrino oscillation experiments (0.05 eV/c2 in case of inverted ordering, or 0.009 eV/c2 for normal ordering). To reach those sensitivities, we are developing new technologies such as a differential detector with sub-eV resolution and an atomic tritium source. For the differential detector, we are currently testing quantum sensors, more precisely, μm-sized cryogenic (10 mK) calorimeters. Additionally, we are currently building a first- of-its-kind setup for creating tritium atoms. Subsequently, these atoms need to be cooled and magnetically trapped. This will be done within the Atomic Tritium Demonstrator to solve key challenges for future atomic sources together with the global community (e.g., Project 8). The talk will first introduce the KATRIN experiment, present its recent results, and then give a short overview of efforts for future neutrino mass experiments.