Marcello Conversi (born 25.08.1917) is an Italian physicist and a member of the Accademia dei Lincei (1970). He was born in Tivoli. He graduated from the University of Rome (1940) and worked there in 1940 — 47. In 1950 —58 he was professor at the University of Pisa and in 1959-61 at the University of Rome. From 1961 he has been at CERN.
His research concerned nuclear physics, the physics of cosmic rays, accelerator technology and high-energy physics. Together with E. Pancini and O. Piccioni he proved experimentally (1947) that the muons of cosmic rays are not strongly interacting particles. He obtained the first experimental indications of the existence of mesic atoms. He built (1955) a hodoscope chamber — one of the early versions of the spark chamber. Together with others he determined the spin of the lambda hyperon in 1958, and proved experimentally the non-conservation of parity in the decay of hyperons (1957).