"A group of us studying natural science and mathematics at the University of Buenos Aires gathered to hear teaching assistant Estrella Mathov talk about her trip to Brazil. Estrella had just returned from a scientific conference that had been attended by many great cosmic-ray physicists, including Cecil Powell, Beppo Occhialini, and Brazil’s own César Lattes. With great enthusiasm, she was telling everybody about the new projects and techniques that were just emerging in cosmic-ray research. Since Estrella was already working with Geiger counters, she encouraged the few physics majors, including me, to get involved with particle detection using nuclear photographic emulsions. That new technique was particularly attractive because it did not require complex and costly electronic equipment."