NEUTRINO, PARTICLE AND COSMIC MESSENGER
The discovery of neutrino oscillations by the Super-Kamiokande experiment in 1998 (Nobel Prize 2015) revealed the existence of tiny neutrino masses as well as lepton flavor mixing. Recently, the T2K long-baseline neutrino oscillation experiment has discovered the electron neutrino appearance and has established the first constraints at a 3-sigma level on a still-unknown CP-violating phase. CP-violation in the lepton sector might be the origin of matter-antimatter asymmetry in the Universe, and therefore is one of the major science goals in the neutrino experiments of the next decade. Neutrinos from astrophysical sources are also of great interest in order to probe the evolution of the Universe. The observation of neutrinos from a supernova SN1987A by the Kamiokande (Nobel Prize 2002) and IMB detectors proved that the basic scenario of the supernova explosion was correct, however, the detailed mechanism of explosions is still unknown. Therefore, the neutrino community is awaiting the next chance to observe supernova neutrino bursts with multi-messenger observations. Another approach is to search for the diffuse supernova neutrino background (DSNB) produced by the supernovae which occurred since the beginning of the Universe, which has a high potential of discovery in the near future.
To improve T2K’s sensitivity to CP-violation in the lepton sector, the ILANCE teams will focus on the near detector ND280 upgrade, where CNRS/IN2P3 and University of Tokyo physicists are playing key roles in coordination of working groups and in the developments for new front-end electronics on the analysis side, both groups from CNRS/IN2P3 and University of Tokyo are leading the development of the very first joint analysis between atmospheric and accelerator-produced neutrinos, essential for future Hyper-K analyses.
The Super-Kamiokande experiment is entering a new phase with the success of the addition of Gadolinium in the water tank to increase the efficiency of neutron tagging. The ILANCE teams took an active part in this upgrade and in the analysis improvement in the search for diffuse supernova neutrino background.
The next-generation Hyper-Kamiokande neutrino experiment in Japan has recently been approved. One of the main physics goals of the experiment is the discovery of CP violation in the lepton sector, but it will also be the most sensitive detector to proton decay as well as a unique observatory for neutrinos from astrophysical sources, such as supernovae neutrinos. Groups from CNRS/IN2P3 and University of Tokyo have strongly contributed to the HK sensitivity studies, including different photo-sensor configurations.
SUPER-KAMIOKANDE EXPERIMENT http://www-sk.icrr.u-tokyo.ac.jp/sk/index-e.html
T2K EXPERIMENT https://t2k-experiment.org/