Bruno Maximovich Pontecorvo (born 22.08.1913) — Soviet physicist, academician (1964, corresponding member 1958). Born in Pisa (Italy). Graduated from the University of Rome (1933) and worked there, then in 1936 — 40 in France, in 1940-43 - in the USA, in 1943-48 - in Canada, in 1948 — 50 — at the Atomic Energy Centre in Harwell in England. Since 1950 he has worked in the USSR. In 1950 —56 —at the Institute of Nuclear Problems of the USSR Academy of Sciences, from 1956 — at the Joint Institute for Nuclear Research (Dubna), from 1961 — also professor at Moscow University.
His work concerned nuclear physics, high-energy physics, the physics of weak interactions, neutrino physics and astrophysics. In 1934, as a member of E. Fermi's group, he took part in experiments on the bombardment of various substances with neutrons, and in the discovery and subsequent study of the slowing down of neutrons and of neutron capture by nuclei, which gave rise to neutron physics. He studied nuclear isomerism. He proposed (1941) a method of prospecting for oil-bearing regions — neutron logging.
He was the first to study the production of neutral pions on protons and nuclei under the action of high-energy neutrons, and investigated the interaction of pions with nucleons and nuclei. He was the first to draw attention to the deep similarity between the muon and the electron, carried out an experiment on the capture of muons by 3He nuclei that confirmed this analogy, and established experimentally the spontaneous decay of the muon into an electron and two neutrinos. Independently of others he tested the law of the pair production of strange particles. Together with others he detected (1959) in heavy elements (thorium, uranium, plutonium) a radiationless transfer of energy from mesons to the nucleus (the radiationless capture of muons in heavy mu-mesic atoms).
In 1946 he proposed using the reaction Cl37 + ν → Ar37 + e- to detect the neutrino. Following Pontecorvo's scheme, experiments were carried out at reactors that proved the neutrino differs from its antiparticle. He proposed an experiment with accelerators to test the existence of two types of neutrino. He suggested (1957) the possibility of neutrino oscillations. He studied the role of the neutrino in the processes of stellar evolution, which contributed to the creation of neutrino astrophysics.
In 1954 Pontecorvo was awarded the USSR State Prize, and in 1963 he was awarded the Lenin Prize for his work on the physics of weak interactions and neutrino physics.
His work concerned nuclear physics, high-energy physics, the physics of weak interactions, neutrino physics and astrophysics. In 1934, as a member of E. Fermi's group, he took part in experiments on the bombardment of various substances with neutrons, and in the discovery and subsequent study of the slowing down of neutrons and of neutron capture by nuclei, which gave rise to neutron physics. He studied nuclear isomerism. He proposed (1941) a method of prospecting for oil-bearing regions — neutron logging.
He was the first to study the production of neutral pions on protons and nuclei under the action of high-energy neutrons, and investigated the interaction of pions with nucleons and nuclei. He was the first to draw attention to the deep similarity between the muon and the electron, carried out an experiment on the capture of muons by 3He nuclei that confirmed this analogy, and established experimentally the spontaneous decay of the muon into an electron and two neutrinos. Independently of others he tested the law of the pair production of strange particles. Together with others he detected (1959) in heavy elements (thorium, uranium, plutonium) a radiationless transfer of energy from mesons to the nucleus (the radiationless capture of muons in heavy mu-mesic atoms).
In 1946 he proposed using the reaction Cl37 + ν → Ar37 + e- to detect the neutrino. Following Pontecorvo's scheme, experiments were carried out at reactors that proved the neutrino differs from its antiparticle. He proposed an experiment with accelerators to test the existence of two types of neutrino. He suggested (1957) the possibility of neutrino oscillations. He studied the role of the neutrino in the processes of stellar evolution, which contributed to the creation of neutrino astrophysics.
In 1954 Pontecorvo was awarded the USSR State Prize, and in 1963 he was awarded the Lenin Prize for his work on the physics of weak interactions and neutrino physics.