He was part of an initial group of young Brazilian physicists who worked under European teachers such as Gleb Wataghin and Giuseppe Occhialini.

His colleagues, who also became important Brazilian scientists, were Oscar Sala, Mário Schenberg, Roberto Salmeron, Marcelo Damy de Souza Santos and Jayme Tiomno.

In April 1947 he visited a weather station on top of the 5,200-meter high Chacaltaya mountain in Bolivia, using photographic plates to register the rays, and reveal more 'pion decay events'.

A year later, working with Eugene H. Gardner (1913-1950[1]) at UC Berkeley, Lattes was able to detect the artificial production of pions in the lab's cyclotron, by bombarding carbon atoms with alpha particles.

After another brief stay in the United States (from 1955 to 1957), he returned to Brazil and accepted a position at his alma mater, the Department of Physics of the University of São Paulo.

In 1967, Lattes accepted a position of full professor with the new "Gleb Wataghin" Institute of Physics at the State University of Campinas (Unicamp), which he helped to fund.

In 1969, he and his group discovered the mass of the so-called fireballs, a phenomenon induced by naturally occurring high-energy collisions, and which was detected by means of special lead-chamber nuclear emulsion plates invented by him, and placed at the Chacaltaya peak of the Bolivian Andes.