Hyper-Kamiokande (HK or Hyper-K) project is the world-leading international scientific research project hosted by the University of Tokyo and High Energy Accelerator Research Organization (KEK) in Japan aiming to start experimentation in 2027.

The project consists of the Hyper-K detector, which has an 8.4 times larger fiducial mass than its predecessor, Super-Kamiokande, equipped with newly developed high-sensitivity photosensors and a high-intensity neutrino beam produced by an upgraded J-PARC accelerator facility.

It is the aim of Hyper-Kamiokande to elucidate the history of the evolution of the Universe and the Grand Unified Theory through an investigation of CP violation (the difference between neutrinos and antineutrinos) and proton decay, together with the observation of neutrinos from supernova explosions.

Peering into the Universe and its Elementary Particles from Underground

After the breakthrough discovery of neutrino oscillations in the Super-Kamiokande experiment in 1998, the properties of neutrinos have been determined, one after another, and it has become necessary to update the Standard Model.

In 2011, the T2K experiment, which used a neutrino beam from the high intensity accelerator J-PARC and the Super-Kamiokande detector, confirmed the third neutrino oscillation. Now that all neutrino oscillation modes have been confirmed, the field of neutrino research has opened up for further investigations and discoveries.

Based on the highly sensitive techniques for neutrino observation cultivated over the years, Hyper-Kamiokande represents a further improvement in sensitivity. The Hyper-Kamiokande detector consists of a cylindrical tank, with a water depth of 71m and a diameter of 68m. The fiducial mass of tank is approximately 10 times larger than that of the Super-Kamiokande detector. On the tank wall, 40,000 ultra high sensitivity photosensors have been installed in order to detect the very weak Cherenkov light generated in the water.

The Hyper-Kamiokande detector is both a “microscope,” used to observe elementary particles, and also a “telescope” for observing the Sun and supernovas, using neutrinos.

Through the realization of the Hyper-Kamiokande project, we will lead neutrino research into the world of the future.

Bringing Neutrino Research to the Next Level

The history of Japan’s large neutrino experiments began with the Kamiokande experiment. The history of its development is summarized here.






Aiming to start observation in 2027

Size Size Size

19m diameter x 16m hight

39m diameter x 42m hight

68m diameter x 71m hight

Water mass ( Fiducial mass) Water mass ( Fiducial mass) Water mass ( Fiducial mass)

4500 ton
(680~1040 ton)

※The waer mass in the tank(inner tank and, upper and bottom outer tank) is 3000 ton

50000 ton
(22500 ton)

260000 ton
(190000 ton)

Photomultiplier Tubes Photomultiplier Tubes Photomultiplier Tubes

50cm diameter / 948

50cm diameter / 11146

50cm diameter / about 40000

Main and expected Results Main and expected Results Main and expected Results
World’s first observation of neutrinos from a supernova explosion and observation of solar neutrinos, leading to the creation of neutrino astronomy Discovery of neutrino oscillations, showing that neutrinos have mass
  1. Discovery of the difference between neutrino and antineutrino oscillations (CP violation) and precise measurements to elucidate the origin of matter in the universe
  2. Further development of neutrino astronomy
  3. Proof of “unification of elementary particles” and “unification of electromagnetic, weak and strong force” by the discovery of proton decay
Major awards Major awards Major awards

The Nobel Prize in Physics 2002
Masatoshi Koshiba

The Nobel Prize in Physics 2015
Takaaki Kajita

Collaboration with the J-PARC Accelerator

In addition to natural neutrinos such as atmospheric neutrinos and solar neutrinos, a high intensity and high quality neutrino beam from the J-PARC accelerator in Tokai, Ibaraki may be used for precise studies of properties such as neutrino CP violation.

Hyper-Kamiokande is expected to observe 30 times as many neutrinos as the T2K experiment after the increase of the J-PARC beam power.