Bruno Rossi (born 13. 04. 1905) is an Italian physicist and a member of the Accademia dei Lincei (1959). He was born in Venice. He studied at the universities of Padua (1923—25) and Bologna (1925-27). In 1928-32 he worked at the university in Florence, and in 1932 —38 he was professor at the University of Padua. Since 1939 he has lived in the USA. In 1939 — 40 he worked at the University of Chicago, in 1940—43 at Cornell University and in 1943—46 at the Los Alamos Laboratory. In 1946 —70 he was professor at the Massachusetts Institute of Technology.
His work concerned cosmic-ray physics, space physics and X-ray astronomy. In 1930 he developed the method of coincidence of discharges for the study of cosmic rays and, using this method, rediscovered cosmic showers in 1933. By studying the rate at which showers are recorded as a function of the thickness of the matter in which they are produced, he obtained the curve of the rate of showers against thickness (the Rossi curve). He showed (1934) that cosmic radiation contains soft and hard components. In 1942 he proposed the method of delayed coincidences for determining the mean lifetime of the muon. He established the existence of primary particles in cosmic rays with an energy of 1020 eV. He proved the existence of the “solar wind”. He was one of the first to detect sources of X-ray emission in space (1962).
A member of the National Academy of Sciences of the USA (1950). The E. Cresson (1974) and B. Rumford (1976) medals and others.