Japan has stored 50,000 tons of ultrapure water at a depth of 1,000 meters underground. What is the purpose for more than 20 years?

Although Japan is an island country, its narrow land area greatly limits Japan's development. However, even so, Japan's scientific research level in many fields can be said to be a world leader, one of which is: Japan has stored 50,000 tons of ultrapure water at a depth of 1,000 meters underground. This has existed for over 20 years. What is the purpose of Japan? What is ultrapure water?

Ultrapure water is an unusual type of water that is produced through a variety of techniques including distillation and deionization. This water is dedicated to neutrino-related research.

Neutrinos are one of the most fundamental particles in nature and are also known as "the most elusive prey in the universe" because they travel close to the speed of light and are so small. However, scientists have gradually discovered that neutrinos behave differently when they encounter water.

Neutrinos react with water as they pass through it. This probability is low, but it is also a breakthrough. So ultrapure water works here. It could help scientists better detect neutrino reactions in water and shield other cosmic rays from interfering with experiments. Japan has prepared a lot of work for this.

Since the 1950s, the University of Tokyo has carried out a research project on neutrinos, which is Japan's more famous neutrino detection device, the Super Kamioka detector.

Even the US lags behind Japan in technology. However, when the technology is up to par, we have to consider the external situation. In addition to funding, we also need to block all kinds of noise.

The best environment is high mountains, but Japan, as an island country, obviously does not have high mountains, so finally an abandoned mine was found in Kamioka. There are many particles. If the depth is not deep enough, neutrinos cannot be detected.

At first, Japan stored thousands of tons of ultrapure water to ensure that neutrinos' reactions through pure water could be detected. It is here that the Japanese team started the "Kamiokande Nuclear Decay Experiment". For the next 20 years, all experiments focused on one purpose - to discover the most mysterious particles.

In 1987, Japan's Kamioka probe finally discovered the neutrinos produced by the explosion of supernova 1987A in the Large Magellanic Cloud. They are neutrinos produced by objects outside the solar system. This is a very important discovery in the scientific community, precisely because This discovery gave the Japanese team the strength to expand the reserves of ultrapure water from thousands of tons to 50,000 tons.

In 1996, after the Super Kamioka detector was officially put into use, the neutrino detection results were announced, which brought two Nobel Prizes to Japan, and Japan's exploration has not stopped.

In 2019, Japan announced that it would build the "Top Kamioka Detector", a new generation of fundamental particle observation facilities. This is an upgraded version of the previous detector with stronger performance, which can also enable Japan to achieve better results in this field, so as to achieve the grand goal of being the leader in this field, which means that Japan's exploration road will also be upgraded to a new stage.