First direct neutrino-mass measurement with sub-eV sensitivity

We report the results of the second measurement campaign of the Karlsruhe Tritium Neutrino (KATRIN) experiment. KATRIN probes the effective electron anti-neutrino mass, mν, via a high-precision measurement of the tritium β-decay spectrum close to its endpoint at 18.6 keV. In the second physics run presented here, the source activity was increased by a factor of 3.8 and the background was reduced by 25% with respect to the first campaign. A sensitivity on mν of 0.7 eV/c2 at 90% confidence level (CL) was reached. This is the first sub-eV sensitivity from a direct neutrino-mass experiment. The best fit to the spectral data yields mν2=(0.26±0.34) eV2/c4, resulting in an upper limit of mν<0.9 eV/c2 (90% CL). By combining this result with the first neutrino mass campaign, we find an upper limit of mν<0.8 eV/c2 (90% CL).

New results and perspectives in neutrino physics

A brief review of new results and perspectives in neutrino physics is presented. An emphasis on a search for CP violation in neutrino oscillations and a search for sterile neutrinos is given. Status of measurement of the direct neutrino mass measurement and searches for neutrinoless double beta decay are also discussed.