July 11, 1924 - Birth of César Lattes, co-discoverer of the meson pi o pion

Cesare Mansueto Guilio Lattes, known as César Lattes, was one of the most brilliant Brazilian scientists of his generation. At the age of just 23, together with the English scientist Cecil Frank Powell and the Italian Giuseppe Occhialini, he discovered a particle inside the atomic nucleus that ensures the cohesion of the atom: the pi meson.

At the time, scientists around the world were wondering how protons were held together in the nucleus of the atom. His interest in these questions led him to move to England, where he worked at the Bristol University Laboratory with Giuseppe Occhialini and Cecil Powell (Nobel Prize in Physics in 1950). Together they discovered a new atomic particle, the pi meson or pion, which decays into a new type of particle, the meson or muon. This marked the beginning of a new area of research: particle physics.

In 1947, to pursue his main line of research into the "study of cosmic rays", Lattes set off for Chacaltaya, one of the highest peaks in the Bolivian Alps, where the rays from space were most intense. There, at an altitude of over 5,000 meters, he exposed photographic plates to the action of cosmic rays, and experimentally proved the existence of heavy mesons or pions.

A year later, at the University of California, he succeeded in producing the meson artificially by accelerating alpha particles in the cyclotron.

If you want to know more about this scientist, click here: César Lattes