By TETSUYA ISHIKURA/ Staff Writer
June 28, 2021 at 07:00 JST
HIDA, Gifu Prefecture--Work started here to build the latest elementary particle observatory with an eye on solving mysteries of the universe and bringing another Nobel Prize in Physics to Japan in the field.
The groundbreaking ceremony for the Hyper-Kamiokande facility was held on May 28 after the digging of a mountain tunnel started earlier in the month.
The system is scheduled for completion in 2027. Construction costs are estimated to total 65 billion yen ($593 million).
Discoveries by its predecessors, Kamiokande and Super-Kamiokande, which were installed in the Kamiokacho district in Hida by the University of Tokyo’s Institute for Cosmic Ray Research (ICRR), have led to two Nobel Prizes in Physics.
The primary goal of Hyper-Kamiokande is to be the first in the world to detect a mysterious phenomenon known as proton decay.
“We want to produce scientific achievements earlier than our rivals,” said Masato Shiozawa, a professor of elementary particle studies at the ICRR, who heads the Hyper-Kamiokande program. “We are looking forward to collecting data after finishing the construction as scheduled.”
The third-generation Hyper-Kamiokande, whose research team comprises 450 individuals from 19 countries, will be set up 650 meters below the ground surface in a mountain.
It will consist of a large cylindrical water tank measuring 68 meters in diameter and 71 meters in height. The tank will contain 260,000 tons of pure water surrounded by 40,000 hypersensitive optical sensors.
The facility will monitor a weak light emitted when an elementary particle called a neutrino, which can pass through normal matter, comes within range.
Procedures to build Hyper-Kamiokande started in March last year, and the ground survey and other processes have already been completed.
The mountain tunnel will be 2 kilometers long. At the end of the passage will be one of the world’s largest underground spaces, which will house the observation facility.
Excavation alone is predicted to take three years.
Hyper-Kamiokande will be five times the size of Super-Kamiokande, and its improved sensitivity will make it possible to gather 100 years of data within a decade.
ICRR Director Takaaki Kajita, co-recipient of the 2015 Nobel Prize in Physics for discovering that neutrinos have mass based on monitoring results of Super-Kamiokande, said he is already proud of its successor.
“More than 20 years have passed since the system’s concept was first proposed, but it will be great that Japan will be able to organize an extremely important experiment in science as a host nation,” Kajita said.
The study of proton decay is of particular note.
Protons are believed to decay, indicating the possibility that all matter in the world will disappear at some point in the future.
Numerous tests have been carried out worldwide to observe proton decay since the 1980s after the phenomenon was theoretically suggested. But none of them have succeeded in detecting proton decay.
The first Kamiokande, proposed by neutrino pioneer Masatoshi Koshiba, who died in 2020, was initially intended to monitor proton decay as well.
The biggest competitor for Japan in the field is the United States. U.S. institutes, such as the Fermi National Accelerator Laboratory, started building a similar facility three years earlier.
Koshiba’s discovery of neutrinos from a supernova explosion, which resulted in his winning of the Nobel Prize in Physics in 2002, came amid fierce competition with the United States and Europe.
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The inside wall covered with optical sensors of Super-Kamiokande in Hida, Gifu Prefecture, in 2006. The number of sensors will be raised fourfold to 40,000 for Hyper-Kamiokande. (Asahi Shimbun file photo)
