at this time he was already working at the physics institute of the ussr academy of sciences.ry. wechsler's measuring instruments, created by him earlier, are perfectly suitable for experiments on the study of elementary particles of cosmic rays. with them began the epic with accelerators, cyclotrons, synchatrons and... one might ask, what does this have to do with these cosmic rays? it turns out that this is a unique natural a source of high ultra-high energies, making it possible to study the processes of transformation of elementary particles and their structure. many physicists were of the opinion that cosmic rays consist of electrons, either to confirm this or to disprove the hypothesis. the institute sent an expedition to the caucasus. wexler was immediately appointed leader of this group. the results of measurements on elbrus made it possible to expand our understanding of the composition of cosmic radiation. in particular , a large number of secondary particles, slow mesons, were discovered. meson is a compound elementary particle responsible for confining protons and