One of the technical wonders at the Institute of High-Energy Physics (IHEF) at Protvino is a unique research unit-a tracer, or tagged neutrino complex (TNC). It was built in the late 1980s-early 1990s by a large team of scientists from Russia, Italy and Germany for research on one of this country's biggest accelerators of the Institute of High-Energy Physics which "speeds up" protons to 70 BeV. Sergei DENISOV, RAS Corresponding Member, department head, Institute of High-Energy Physics (Protvino); Vladimir LIPAYEV, Cand. Sc. (Phys. & Math.), senior researcher; Anatoly PETRUKHIN, Dr. Sc. (Phys. & Math.), Professor of the Moscow Institute of Physics and Engineering; and Rostislav KOKOULIN, Cand. Sc. (Phys. & Math.), senior researcher Neutrino is born in the process of bombardment of a special target with an accelerated beam of protons during the decay of charged pi- and K- mesons * . If a mu- meson (muon) appears thereby, this neutrino is called muonic; and if an electron is produced, it is called electronic. There are definite distinctions between the two. Meson decays occur in a long tube in which high vacuum is maintained in order to rule out the particles' interaction with the air. Usually a thick steel shield, weighing thousands and even tens of thousands of tons, was placed right behind it to absorb all generated particles except neutrinos. These are known for very weak interactions with matter, which means that a shield of tens or hundreds of meters is no barrier for them. Placed next was a neutrino detector combining the function of a target, which is bombarded by neutrinos, and that of a tracer of the products of their interactions. This being so, the unit had to be very massive to capture at least some of the "invisibles". The above standard layout of the experiment, however, has some serious drawbacks. It does not provide for reliable determination of such key neutrino parameters as energy, flight trajectory and type (electronic or muonic, ... Читать далее