Feynman spent several weeks in Rio de Janeiro in July 1949. That year, the Soviet Union detonated its first atomic bomb, generating concerns about espionage. Fuchs was arrested as a Soviet spy in 1950 and the FBI questioned Bethe about Feynman's loyalty. Physicist David Bohm was arrested on December 4, 1950 and emigrated to Brazil in October 1951. Because of the fears of a nuclear war, a girlfriend told Feynman that he should also consider moving to South America. He had a sabbatical coming for 1951–52, and elected to spend it in Brazil, where he gave courses at the Centro Brasileiro de Pesquisas Físicas. In Brazil, Feynman was impressed with "samba" music, and learned to play the "frigideira", a metal percussion instrument based on a frying pan (".") He was an enthusiastic amateur player of bongo and conga drums and often played them in the pit orchestra in musicals. He spent time in Rio with his friend Bohm but Bohm could not convince Feynman to investigate Bohm's ideas on physics.