KATRIN

Experiment for measuring antineutrino mass

KATRIN is a German acronym (Karlsruhe Tritium Neutrino Experiment) for an undertaking to measure the mass of the electron antineutrino with sub eV precision by examining the spectrum of electrons emitted from the beta decay of tritium. The experiment is a recognized CERN experiment (RE14). The core of the apparatus is a 200 ton spectrometer. In 2015, the commissioning measurements on this spectrometer were completed, successfully verifying its basic vacuum, transmission and background properties. The experiment began running tests in October 2016. The inauguration took place 11 June 2018, with the first tritium measurements by the experiment (the so called First Tritium or FT 2 week engineering run in mid 2018). The projected experiment duration at the time was 5 years. The first science measurements (so called first campaign) took place 10 April 2019. In February 2022, the experiment announced an upper limit of mν < 0.8 eV c–2 at 90% confidence level.

[[File:41567 2021 1463 Fig1 HTML. webp|thumb|Illustration of KATRIN beamline and its main components. Instead, it was shipped by water, down the Danube to the Black Sea, through the Mediterranean Sea and Atlantic Ocean to Rotterdam, then up the Rhine to Karlsruhe. This 8600 km long detour limited land travel to only the final 7 km from the Leopoldshafen docks to the laboratory. The construction proceeded well with several of the major components on site by 2010. The main spectrometer test program was scheduled for 2013 and the complete system integration for 2014. The experiment is located at the former Forschungszentrum Karlsruhe, now Campus Nord of the Karlsruhe Institute of Technology.

thumb|right|upright=1.5|Energy spectrum of the electrons emitted in tritium beta decay. Three graphs for different neutrino masses are shown. These graphs differ only in the range near the high energetic end point; the intersection with the abscissa depends on the neutrino mass. In the KATRIN experiment the spectrum around this end point is measured with high precision to obtain the neutrino mass. [[File:NeutrinoMassTimeline2022. webp|thumb|left|Timeline of neutrino mass measurements by different experiments. As of September 2019, the experiment hopes to achieve 3 measuring campaigns, each comprising 65 days of active measurement, in a year. The experiment reckons it needs 1000 days of measurement to reach target sensitivity of 0.2 eV (upper limit for neutrino mass). Thus the final results are expected in 5–6 years. The February 2022 upper limit is mν < 0.8 eV c–2 at 90% CL in combination with the previous campaign. Along with the possible observation of neutrinoless double beta decay, KATRIN is one of the neutrino experiments most likely to yield significant results in the near future.