Water is a very important resource for human beings . Since the end of the last century, Japan has stored 50,000 tons of ultrapure water at a depth of 1,000 meters underground for more than 20 years . People can't help but wonder, is this for daily drinking?

Pure water for daily drinking contains almost no impurities . Why does Japan store ultrapure water instead of pure water?

What exactly is ultrapure water and what does it do?

Does China have corresponding research on ultrapure water ?

Next, this article will explain these questions from the following aspects: 1. What is ultrapure water? Second, the role of ultrapure water.

Japanese ultrapure water

3. What does Japan use to store ultrapure water?

4. What achievements has China made in ultrapure water?

What is ultrapure water?

We want to know the purpose of storing 50,000 ultrapure water in Japan, we must first know what ultrapure water is .

Water is made up of two hydrogen atoms and one oxygen atom

The composition of water is two hydrogen atoms and one oxygen atom, that is, H2O . In addition to this, ordinary water also has other impurities, such as bacteria and viruses.

The mineral water we drink also contains a certain amount of minerals, trace elements or other components.

Ultrapure water is also different from them. Ultrapure water is relatively pure and contains almost no other chemical components.

Ultrapure water is free of any other organic matter except two hydrogen atoms and one oxygen atom .

That is to say, ultrapure water is water in addition to water. Although it looks very healthy and does not contain trace elements like mineral water, it is actually not suitable for drinking. Long-term drinking will lack the trace elements needed by the human body.

In addition, ordinary water is a conductor because it contains a large amount of positive and negative ions, but ultrapure water can be said to be almost non-conductive because it does not contain ions .

Only the ultrapure water of H2O can be obtained by extraction, and it cannot be obtained through ordinary procedures. To produce ultrapure water, a series of complex and fine techniques such as application of distillation, deionization, reverse osmosis technology, etc. are required.

Ultrapure water process flow chart

So what kind of use does Japan spend so much effort in developing ultrapure water?

What is ultrapure water used for?

In fact, the real use of ultrapure water is the water produced for the development of ultrapure materials such as semiconductor materials and nano-fine ceramic materials .

'Super Kamioka'' photoelectric sensor detects neutrinos as flashes

But the ultrapure water stored in Japan is used to detect neutrinos, using ultrapure water to detect the presence and vibrations of neutrinos.

The concept and properties of neutrinos must be explained here. Neutrinos exist widely in nature , but they are extremely light and uncharged elementary particles.

Because of their tiny mass, neutrinos can travel at nearly the speed of light .

Amazingly, neutrinos are everywhere because they can penetrate any particle and can travel through almost all matter on Earth.

One of nature's most fundamental particles, the neutrino

Whether it is a living body or a non-living body, it is very weak when it reacts with other objects.

Very weak is embodied in the fact that many neutrinos are in contact with matter but not necessarily react with the matter. If it is a specific number , only one neutrino in 10 billion neutrinos will interact with matter. react, so that the neutrino appears to have a stealth function.

cosmic rays

It can be seen that it is very difficult to understand the existence of neutrinos. To observe neutrinos, the instrument must first be large enough to exclude external interference, including cosmic rays.

Then the effect of ultrapure water comes out at this time. Ultrapure water does not contain any impurities, and it is one of the very few substances that can react with neutrinos .

speed of light

When neutrinos pass through ultrapure water at ultra-high speed, they will have different degrees of decay. The neutrinos will become high-speed moving ions , and the maximum speed can even exceed the speed of light traveling in water. It is possible to capture such changes.

Japan's Super Kamioka Probe

Next, let's look at the answer to the third question. After having these five tons of ultrapure water, how does Japan store it?

Super Kamioka Probe

That's right, it was stored using Japan's Super Kamioka probe .

As mentioned above, to detect the existence of neutrinos, the environment that may interfere with the experiment must be excluded. It is not easy to find "invisible people" in a busy downtown, so this container is best built in inaccessible places, usually in underground.

The Super Kamioka detector was built 1,000 meters below an abandoned mine in Gifu Prefecture, Japan .

The Super-Kamiokande detector is a stainless steel cylinder

From the outside, it looks like a large stainless steel cylinder with a diameter and height of an astonishing 40 meters!

From the inside, there are countless golden spheres distributed on the inner wall of this cylinder.

Inside, there are 50,000 tons of ultrapure water stored to detect neutrinos .

It takes so much effort to build a large detector to increase the odds of detecting neutrinos.

Workers install photomultiplier tubes

Let's take a look at the working principle of Japan's Super Kamioka detector. Although neutrinos are invisible to the naked eye, there are a large number of them, and there are also a lot of ultrapure water in the detector, a full 5 tons, neutrinos and ultrapure water . The chance of a reaction also increases.

Once the neutrinos pass through the ultrapure water here, the reaction occurs, and the small balls here, that is, the photomultiplier tube , will amplify this reaction, that is, it is clearly seen that the ultrapure water reacts with the neutrinos. Cherenkov light and record it.

The glass surface of the photomultiplier tube is handcrafted by artisans

It is not easy to observe the reaction between neutrinos and ultrapure water, but under the premise of using human intelligence, we know that it is possible to use photomultiplier tubes to amplify the Cherenkov light generated by the reaction to make detection relatively easy .

The further purpose of observing Cherenkov light is to discover supernova explosions in the Milky Way by detecting proton decay. Studying supernova explosions is beneficial to revealing the mysteries of the formation of the universe.

Milky Way structure map

However, in Japan at that time, the decay of protons was not observed.

No country today has been able to detect proton decay, but Japan, unintentionally, has detected the presence of solar neutrinos, which will advance this research.

What achievements has China made in neutrino detection?

The Kamioka detector we mentioned now has actually been built in Japan in the last century, which shows that Japan attaches great importance to technology and is constantly seeking breakthroughs .

Nobel Prize

Japan's research in this area has won them 2 Nobel Prizes.

And Japan also plans to build a larger detector called the top-level Kamioka detector, which is an enhanced version of the Kamioka detector.

The capacity of this top-level Kamioka detector is five times that of the Kamioka detector, reaching 260,000 tons!

Japan is at the forefront of science and technology, so what achievements have we made in this field?

Although the technology in our country was not very developed in the last century , our scientific research workers have been working silently. In order to make China's science and technology continue to develop, they put all their energy into research and practice.

As one of the most important topics in recent years , neutrinos are not far behind and will definitely keep pace with the times.

After that, the country successfully carried out the Daya Bay Reactor Neutrino Experiment . Because of this achievement, China's neutrino research has entered an international leading position in one fell swoop . results".

One of the Daya Bay probes

After that, China established the Jiangmen Neutrino Experiment Station in Jiangmen City, Guangdong Province . This experimental station is expected to be put into use in 2023. At that time, it will be the world's most accurate and largest liquid scintillator detector.

The advanced version of Jiangmen Neutrino Experiment Station is to measure the mass order of neutrinos. Compared with Japan's top Kamioka Experiment and the American Dune Experiment , our experimental station has the advantage that nuclear reactions are relatively easy to capture, because the production of The number of neutrinos is very high.