Solar neutrinos

The sun can be compared to a "black box", in which astronomers observe only "output". All information about the Sun has been obtained, thanks to the investigation of various radiations originating in its uppermost layers. Directly from the bowels of the Sun, no information comes to us. Thus, the theory of the internal structure of the Sun is, strictly speaking, only a theoretical model. Therefore, astronomers need information directly from the bowels of the Sun. It can be obtained by examining, for example, solar neutrinos.

Therefore, astronomers need information directly from the bowels of the Sun. It can be obtained by examining, for example, solar neutrinos

Neutrinos are an "elusive" particle that takes a direct part in thermonuclear reactions. In particular, neutrinos are formed in the process of thermonuclear transformations of hydrogen into helium, which, according to modern concepts, serve as sources of intrastellar energy. The energy of these particles and the magnitude of their flux depend on the temperature and nature of the nuclear reactions. In addition, solar neutrinos, which have a huge penetrating power, pass through the entire solar stratum almost unimpeded and reach the Earth. Therefore, solar neutrinos provide information about the state of the Sun almost at the time of observation.

If we succeeded in "catching" solar neutrinos, we would in a sense "see" what is happening in the center of the Sun. But it is possible to observe them only indirectly, by forcing to interact with other particles and recording the results of such interactions.

A suitable nuclear reaction can be the interaction of a neutrino with the core of one of the chlorine isotopes, with an atomic weight of 37. By catching solar neutrinos, such a nucleus turns into the nucleus of the isotope argon-37, which is radioactive, which means that it can be measured after a certain amount of time, how much it accumulated.

But other cosmic rays can also cause a nuclear reaction to convert chlorine into argon. To get rid of such interference, it is necessary to carry out all measurements deep underground, where ordinary cosmic particles can not penetrate.

The idea of such a "detector" for recording solar neutrinos was proposed by B. Pontecorvo and implemented by R. Davis. "Neutrino telescope" served as a huge tank, filled with 600 tons of perchlorethylene. The equipment was installed in an abandoned gold mine in South Dakota.

Solar neutrinos have been observed for a long time in several series. It turned out that the number of registered acts of interaction is much less than predicted by theory!

To explain this, some scientists suggested that the solar thermonuclear reactor operates in a "pulse mode". That is, in the bowels of the Sun the thermonuclear reaction ceases from time to time. And then the Sun shines due to the energy reserves accumulated in the previous cycle. Does not the absence of solar neutrinos in Davis' experiments mean that in our era the solar thermonuclear reactor does not work at all?..

One thing is obvious: to solve the problem, solar neutrinos require continuation of observations.