Leon Max Lederman (born 15.07.1922) is an American experimental physicist and a member of the National Academy of Sciences (1965). He was born in New York. He graduated from the City College of New York (1943) and from Columbia University. In 1951—79 he worked at Columbia University (professor from 1958 and from 1968 director of the Columbia accelerator). Since 1979 he has been director of the E. Fermi National Accelerator Laboratory.
His research has concerned the physics of elementary particles. He measured (1951) the mean lifetime of the pi meson and detected (1952) the interference of nuclear and Coulomb scattering on carbon. In 1956 he discovered the neutral kaon (the K02 meson) and measured its lifetime. In 1957, together with R. Garwin, he proved the nonconservation of parity in the decays of pi mesons and muons and measured the magnetic moment of muons, and he gave the first indirect evidence of the formation of muonium. He compared the lifetimes of particles and antiparticles: of muons (1963) and of pions (1966). The proof that they are equal was a test of the CPT theorem. Together with others he discovered two types of neutrino, the muon and the electron neutrino (1962), the antideuteron (1965) and the upsilon particle (1977). He opened a new line of research in experimental high-energy physics — the study of the production of lepton pairs in hadron collisions.
The National Medal of Science (1967).