T2K

The experiment T2K (Tokai to Kamiokanda) is a long baseline neutrino oscillation experiment, which measures the conversion of neutrinos on a distance of 295 km between their production at the Japan Proton Accelerator Center (JPARC) in Tokai at the east coast of Japan and their detection in the Super Kamiokande detector in the western japanese village of Kamioka. The T2K collaboration is a truly international effort of about 500 accelerator scientists and particle physicists from institutes from 11 countries. One of the primary goals of the experiment was to observe the appearance of electron-type neutrinos from an initial beam of muon-type neutrinos that have traveled 295 km of subterranean Japan. First indications showed up in the year 2011, the final proof succeeded by a publication in 2013. Since 2014 also anti-neutrinos are produced at JPARC and their oscillations on the way to Super-Kamiokande are studied. This might reveal possible differences in the oscillations between neutrinos and antineutrinos ( CP violation in the leptonic sector ) and thus a possible explanation for the asymmetry between matter and antimatter in the universe .

T2K uses a high-intensity neutrino beam operating at an energy that maximizes the probability of oscillation into electron neutrinos. At JPARC a proton beam of 30 GeV energy is sent to a graphite target producing secondary pions which subsequently decay into muon neutrinos. The proton accelerator with a design power of 0.75 MW provides 10²¹ protons on target (POT) per year. The near detector ND280, located 280 m close to the neutrino source, measures the flux and content of the beam, for example to study the beam contamination by other type of neutrinos (ν_e), to reduce systematic effects. As far detector serves Super-Kamiokande, a 50 kt water Cherenkov detector. The experiment uses the world's first off-axis neutrino beam where the line joining JPARC to Super-Kamiokande is at an angle of about 2,5° with respect to the beam direction. This has the advantage of creating an almost mono-energetic neutrino beam which facilitates the interpretation of the recorded data.

The main contributions of our group are:

T2K Gas monitoring chamber for the TPCs at the near detector ND 280