297 PONTEKORVO 



and L. Landau. Limits of utilization of the theory of Brems- 

 strahlung of electrons and pair production at high energies. 

 Doklady Akad. Nauk S.S.S.R., 1953, 92, #3. 

 On the theory of liquid He3. Zhur. Eksptl. i Teoret. Fiz., 

 1950, #10. 



Maximal energy which can be possessed on the surface of 

 the earth by primary electrons of cosmic rays because of 

 radiation in the earth's magnetic field. Zhur. Eksptl. i Teo- 

 ret. Fiz., 1939, #8. 



Office: Moscow Physical Engineering-Physical Institute 



Moscow, USSR 



Residence: Nab. Gor'kogo 4/22 

 Moscow, USSR 



Telephone: Bl 75 76 



PONTEKORVO, BRUNO MAKSIMQVICH (Physicist) 



B. M. Pontekorvo was born August 22, 1913. After graduat- 

 ing in 1933 from the University of Rome, he taught there. In 

 1936-1940 he worked in scientific organizations in France, 

 1940-1948 in the United States, and in 1948-50 at the Harwell 

 Laboratories in England. Since 1950 he has been working in 

 the U.S.S.R. In 1955 he became a member of the Communist 

 Party of the Soviet Union. He was elected in 1958 a Correspond- 

 ing Member of the U.S.S.R. Academy of Sciences. 



Pontekorvo showed, in 1936-39 while studying nuclear iso- 

 merism, that isomeric transitions have a large internal con- 

 version ratio. He obtained a beta-stable isomer by neutron 

 irradiation of cadmium. Exciting nuclei by X-ray radiation, he 

 discovered the phenomena of "nuclear phosphorescence". He 

 proposed in 1943 neutron logging. In 1948, while measuring the 

 beta spectrum of tritium, Pontekorvo showed that the mass of 

 neutrino does not exceed 1/500 electron mass. He was the first 

 to observe L-capture. While studying decay of u -mesons, he 

 ascertained that during this process there was no emission of 

 gamma rays, but the product of the decay was the electron. 

 Pontekorvo pointed out the analogy between the processes of 

 the capture of the u -meson with a K- shell and the usual K- 

 capture of the electron. After 1950 Pontekorvo investigated the 

 production of 7r° -mesons by neutrons. He predicted in 1951 

 production of heavy mesons with hyperons. From 1955 he 

 studied the interaction of 7r-mesons with nucleons. 



