The Tokai to Kamioka long-baseline neutrino oscillation experiment (T2K) studies neutrino oscillations (the transition between different kinds of neutrinos) which occur during the 295km flight of neutrinos from J-PARC to the far detector, Super-Kamiokande. KEK IPNS, in collaboration with the University of Tokyo, ICRR, is promoting the T2K experiment as one of the host institutions.

T2K made the world’s first discovery of a new type of neutrino oscillation -- oscillations from muon-type neutrinos to electron-type neutrinos -- in 2013. Subsequently, we are exploring if particle-antiparticle symmetry (CP symmetry) is violated in neutrinos by measuring muon-type to electron-type neutrino oscillations for both neutrinos and antineutrinos, and comparing the results. Using the data collected by T2K until 2020, we found a hint of CP violation in neutrinos. To confirm this, we will continue making measurements using an improved experimental apparatus.

The KEK/J-PARC neutrino group is conducting various research activities related to T2K. Please also see each research activity page.