Overview

Bringing Neutrino Research to the Next Level

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. Hyper-Kamiokande consists of a cylindrical tank, with a water depth of 71m and a diameter of 68m. The fiducial volume 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.

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

The large neutrino detectors in Japan

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

Size	Size	Size
Kamiokande 1983～1996	Super-Kamiokande 1996~Present	Hyper-Kamiokande Aiming to start observation in 2027
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	Discovery of the difference between neutrino and antineutrino oscillations (CP violation) and precise measurements to elucidate the origin of matter in the universe Further development of neutrino astronomy 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.

About Hyper-Kamiokande