SK2HK, Super-Kamiokande (SK) to Hyper-Kamiokande (HK), is part of the ongoing global efforts to understand the most fundamental elements of matter and their interactions. We aim to investigate neutrino interactions using the existing experimental facility in Japan, the SK detector located in the Kamioka Observatory (Gifu Prefecture) and owned by the partner of this Project: the Institute for Cosmic Ray Research of the University of Tokyo (ICRR).
SK is a very big (50000 tons) instrumented pure water tank that measures the radiation Cherenkov generated by energetic charged particles traveling along its inside. External particles, for instance neutrinos, might interact with particles in the detector. The final state interaction consists of newer particles, many of them charged and therefore able to be measured by SK. From those measurements we can learn about the interaction process and the fundamental physics behind. The SK detector is located underground, approx. 1000 m overburden, to reduce the flux from cosmic ray muons arriving to the detector.
We have upgraded SK (to SuperK-Gd) by dissolving a salt of Gd on its water. The very large neutron capture cross section of the Gd, with photon emission in the process (approx. 8 MeV total energy) allows precise identification of neutrons which will be key in the discovery of the DSNB (Diffuse Supernova Neutrino Background).
We are working on the new generation neutrino experiment, the HK project. It consists of a) a huge "far detector", SK-like device (approx. 200000 tons), being built also at Kamioka, b) an upgraded neutrino beam made at JPARC (Japan Proton Accelerator Research Complex, Ibaraki prefecture) and directed to Kamioka, and c) an additional "near detector", IWCD (Intermediate Water Cherenkov Detector), to measure with unprecedented precision the characteristics of the neutrino beam at generation.
SK2HK addresses fundamental problems in Physics at different stages, by analyzing the SK data, and by designing and building HK-FD and IWCD. These are neutrino oscillations, the search for dark matter, the physics of nearby galactic supernova, the DSNB, and Grand Unification. The collaborative work with the leaders of the field (ICRR holds two Nobel Prices in Physics: M. Koshiba in 2002, and T. Kajita in 2015) provides us with invaluable experience.
