"Super-Kamiokande" of the University of Tokyo in Hida City, Gifu Prefecture is a research facility that observes "neutrinos", one of the elementary particles constituting all substances, with a height of 40 meters, The interior is filled with 50,000 tons of water.

On a huge wall, a sensor that captures the weak light that comes out when the neutrino hit the water is placed on one side, and the upper part of the facility was opened for the first time in 12 years this time due to renovation work It was.

It was opened at the entrance for checking about 4 meters around the corner, and there is almost no impurities in the water, so you can look over the sensor below 40 meters.

In repair work, we will pull out all water by August, replace some sensors, and add gadolinium to new water to improve the accuracy of observation.

With this, we will challenge the world's first observation of neutrinos emitted from the early universe due to the explosion, "supernova explosion" that occurs when a heavy big star in the universe reaches the end.

In a research using Super Kamiokande, in 1975 the director Takaaki Kajita of the University of Tokyo came up with "Kamiokande" as the predecessor, Masatoshi Koshiba of the University of Tokyo special honorary professor in 2002 , Each received the Nobel Prize in physics.

Professor Masayuki Nakahata, a representative of the experiment at Super Kamiokande and professor at the University of Tokyo, commented, "If you succeed in new observations, you can learn more about how elements around you were created. Since I am a facility that has been running the cutting edge of it, I'd like to continue running the forefront. "