What is a neutrino?
In the late 20s of the twentieth century, when scientists are studying the decay p (that is, the atomic nucleus radiating out the electron transforms into another kind of nucleus) discovered in the process Where the energy goes, which is unknown. That made them extremely skeptical: in the subatomic process, is the current law of conservation of energy still valid? The Austrian physicist Pauli aged 30 years, firmly believed in the law of conservation of energy, and with outstanding intuition, predicted: a new kind of particle must be emitted in the process. It has no electric charge and its mass is so small, its interaction with matter is so weak that it can not be measured. It is that taking away that energy part. He called this unknown particle, “the small centipede,” the present-speaking neutrino.
In 1942, according to the method proposed by Chinese physicist Wang Qingheng, American physicist Iren proved for the first time the existence of neutrinos indirectly through experiments. Because the interaction of neutrinos with matter is very weak, it is extremely difficult to observe it directly. Even Iren himself thinks that neutrinos may be permanently unavailable. However, the difficulty did not prevent the progress of science. Twenty-six years after Pauli proposed the neutrino hypothesis, Professor Reines and a few people at the University of California put 400 liters of aqueous cadmium acetate aqueous solution into a new nuclear reactor. Neutrino source), measuring 2.8 neutrinos per hour, is completely consistent with his theoretical prediction. For that reason, Reines was honored to receive the 1995 Nobel Prize in physics.
Modern Cosmological research tells us that the upper limit of the type of neutrino is 3; that is, there are three types of neutrinos. In addition to the electron neutrino discovered above, there are also dock neutrinos (discovered in 1962) and type I neutrinos (discovered in 1975). Each type of neutron has the same antineutrino.
After all, whether or not neutrinos have mass is the key that people are most interested in this research field. Before the 70s of the twentieth century, it was most widely believed that a neutron’s mass was zero. In 1980, the Soviet Institute for Theoretical and Experimental Physics Research announced that over ten years of experimental measurement received the neutron’s mass in the range of 17- 40 electrons. That made a stir in the world of physics. Later, many famous laboratories in the world bustling apply different methods to measure and test that result.
Experts from the Chinese Institute of Atomic Energy Science also developed this research item in the mid-80s and obtained certain results. Currently, the mass measurement experiments of neutrinos around the world are still underway. According to the most recent reports, it is still impossible to rule out the possibility of its mass being zero. Its upper limit of mass is about 10 electrons. Perhaps the reader will ask, the interaction of neutrinos with matter is extremely weak, difficult to grasp; what does it mean to study it?
Of course, a neutrino is not worth anything. Still, in our Universe, the number of neutrinos is so many, it is abundant in every corner of the Universe. On average, there are about 300 neutrinos per cm3, approximately the same as the photon, several billion times more than all other particles! So, the whole neutrino has a very important effect on the Universe.
Also, the neutrino has the ability: it can pass through the interior of stars easily. So it can bring us internal information about the stars of the Sun. Scientists also hypothesized to take advantage of this feature of neutrinos to scan the Earth layer, making the mysteries deep in the Earth reveal nothing. They also want the neutrinos to transmit information across the Earth, so long-distance communication may not need to go through satellites and loop around the earth stations. When one is aware of neutrinos, it has a very wide range of applications.