of the Bolshevik Revolution and arrived in Turin as a refugee. He graduated in Physics and Mathematics and became Italian citizen in 1929. His research activity brought him to get in touch with the major physicists of those years, like Pauli, Heisenberg, Dirac, Gamow, Yukawa, Schrödinger, Bohr, Compton, Bogolubov. In 1934, partly because of the political situation, he accepted a chair at the University of São Paulo in Brazil, where he created a prestigious physics school of international level. Cesare Lattes graduated with him in 1943 and Giuseppe Occhialini worked with him from 1937 to 1942. At the end of 1948, he was assigned the Chair of Experimental physics in Turin, where he guided, together with Romolo Deaglio and Mario Verde, the rebirth of Turin physics school.

[^54]: Seeof the obtained tracks was on the order of a few hundreds micrometers and the measuring of the scattering angles, in particular, required time and a high precision.

[^59]: It is interesting to point out that these cosmic-ray expeditions were organised right in the years when CERN was created. They were the first great European physics research collaborations after the war. Such international collaborations marked the beginnings of Big Science in Europe and, from a social and political point of view, they represented a sign of the overcoming of the divisions and oppositions between people that had been generated by the war. In fact, they showed how science could play an important role to keep and enhance pacific relations and cooperations between European countries: a dream expressed by Niels