the A-bomb during the war. As a foreign national, he couldn't work on the project, so instead he joined the cosmic-ray physics group at Bris- tol. Occhialini's mountain training proved useful as he dragged photo- graphic emulsions up to the Pic du Midi at twenty-eight hundred meters in France. Today you c

events were observed with emulsions taken to an elevation almost twice as high as Pic du Midi. In October of 1947, in the journal Nature, Pow- ell, Occhialini, and Powell's student Cesare Lattes published a paper in which they named the initial meson the pion—which seemed to inter- act with the nuclear str