30-06-2025
Japan's latest particle detector on way to 2028 completion
Reporters take an inside look of an underground cavity for the Hyper-Kamiokande elementary particle detector under construction in Hida, Gifu Prefecture, on June 28.(Shigetaka Kodama)
HIDA, Gifu Prefecture—The cutting-edge elementary particle observation facility here where it is hoped proton decay will be observed for the first time is on track to open in 2028 with a giant underground cavity nearing completion.
The excavation site for the Hyper-Kamiokande facility, which lies 600 meters below ground, was shown to the media on June 28.
The Hyper-Kamiokande, whose construction calls for about 65 billion yen ($450 million), is the third-generation detector after the Kamiokande and the Super-Kamiokande facilities, which helped Japanese scientists earn two Nobel Prizes in Physics.
At the latest observatory, scientists hope to observe the decay of protons, which could lead to a third Nobel Prize, among other physical phenomena.
The facility is also expected to provide clues to the birth of the universe and other materials.
Journalists were allowed into a cavity 69 meters in diameter and 94 meters in height, one of the largest of its kind.
The opening has been created by blasting hard bedrock over more than two years, and the excavation work will be completed in July.
Masato Shiozawa, a professor of elementary particle studies at the University of Tokyo's Institute for Cosmic Ray Research, was on hand to report on the status of the project on June 28.
'We are relieved now that completion of the cavity, which does not have any parallel in the world, has come into sight,' said Shiozawa, co-representative of the Hyper-Kamiokande project, which involves 640 researchers from 22 countries.
'The hard part of installing equipment through international cooperation still lies ahead of us,' he said. 'We want to generate research results that could change people's understanding of elementary particles and surprise everyone.'
Work will start in August to build a cylindrical tank, which will be filled with 260,000 tons of ultrapure water, and install 20,000 to 40,000 ultrasensitive photosensors.
The sensors are designed to capture faint light that will be released by neutrinos, a type of elementary particle.
The amount of water that can be held in the tank, which is greater than the Super-Kamiokande, will allow the Hyper-Kamiokande to obtain 8.4 times more data than its predecessor.
Construction for the project started in 2020, but designs have since been changed and completion has been delayed by about a year due to rising material prices.
Masatoshi Koshiba, a special university professor emeritus at the University of Tokyo, won the Nobel Prize in Physics in 2002 for the first detection of neutrinos, subatomic particles generated by a supernova explosion, at the original Kamiokande observatory that he built.
Takaaki Kajita, one of Koshiba's students and a distinguished university professor at the University of Tokyo, received the 2015 Nobel Prize in Physics for the discovery of neutrino oscillations, which shows that the elementary particles have mass, at the Super-Kamiokande.
