Bruno Pontecorvo

Bruno Pontecorvo (Pisa, Italy 1913 – Dubna, Russia 1993) was an italian atomic physicist, early assistant of Enrico Fermi then author of numerous studies in high energy physics, especially on neutrinos. He became notorious, even outside the scientific community, because of his volunteer transfer to the USSR in 1950 were he continued his researches on the decay of muon and on neutrinos. To his memory, the prestigious Pontecorvo Prize has been instituted in 1995.

Born in a wealthy Jewish and non-observant italian family, at only 18 he was admitted to the Course of Physics held by Enrico Fermi at the University of Rome, becoming one of the closest (and the youngest) assistant of Fermi and one of the so called Via Panisperna's boys (as the Fermi's group of scientists is often recalled, after the name of the street where their laboratory was).

In the 1934 he contributed to the famous Fermi's experiment showing the properties of slow neutron that leaded the way to the discovery of the nuclear fission.

In 1936 he moved to Paris working at the laboratory held by Irène and Frédéric Joliot-Curie on effects of collisions of neutrons with protons and to the electromagnetic transitions among isomers. In this period he got influenced by socialist theories to which he remained loyal for the rest of his life. In Paris, in 1938, he joined with Marianne Nordblom, a young student of french literature, having from her in the same year his first son.

Unable to return to Italy because of 1938's fascist racial discrimination against the Jewish, he remained in Paris until the Nazis entered in the city, then he fled with his family to Spain and shortly after to the USA, where he had found an employment for an oil company in Tulsa (Oklahoma). There he developed a technology and an instrument for well logging (that he forgot or did not mind to patent), based on the properties of neutrons that may be considered the first practical application of the the Via Panisperna boys discovery of slow neutrons.

In the USA, probably because of his socialist faith that he never hidden, he was not called to participate to the Manhattan Project for the construction of the atomic bomb but in 1943 was asked to participate to theoretical studies in a research center in Canada near Montreal, where he concentrated on cosmic rays, on neutrinos and on the decay of muons.

In 1948, after he obtained the British citizenship, he was called by John Cockcroft to contribute to the project of the british atomic bomb and shortly after he was appointed as professor at the University of Liverpool.

On August 31, 1950, in the middle of a holiday in Italy, without informing nor friends nor relatives, he abruptly left Rome for Stockholm with his wife and three sons and the day after, as he unveiled many years later, he was helped by soviet agents to enter in the USSR, where for years he was kept completely isolated from the rest of the world.

His abrupt disappearing caused lot of concern to many of the western intelligence services, mostly to the British and American ones, worried of the escape of atomic secrets on behalf of the Soviet Union after the then recent case of Klaus Fuchs (a german scientist with british citizenship since the 1942 that had participated to the project of the british american bomb and had confessed to spying for the Soviet Union and was sentenced to 14 years in prison.). But as it was pointed out immediately, Pontecorvo had had only limited access to "secret subjects" and even later no allegation of spying or of transferring of secrets to the Soviet has never been made against him.

In the USSR was welcome with all the honors and given a number of privileges reserved only to the Soviet nomenclature. He worked until his death in what is now the Joint Institute for Nuclear Research (JINR) in Dubna, concentrating entirely on theoretical studies on high energy particles and continuing his researches on neutrinos and decay of muons, for which he received first the Stalin Prize in 1953 then the membership to the Soviet Academy of Sciences in 1958. Only in 1955 he was consent to appear in public, at a press conference, where he explained to the world the motivations of his choice for leaving the western world and for preferring working in the USSR. Only many years later, the first time in 1978, he was allowed to travel to Italy. He died in Dubna in 1993, afflicted by the Parkinson's disease.

In 1955, in recognition of his scientific merits, the prestigious Pontecorvo Prize has been instituted by the now russian Joint Institute for Nuclear Research. The prize, awarded annually to an individual scientist, recognizes “the most significant investigations in elementary particle physics,” as acknowledged by the international scientific community.

The scientific work of Bruno Pontecorvo is full of formidable intuitions, some of which have represented milestones in modern physics, e.g.:

• the intuition of how to detect anti-neutrinos generated in nuclear reactors (methodology used by Frederick Reines which were awarded for this with the Nobel prize in 1995);
• the prediction that neutrinos associated to electrons where different from those associated to muons (for which experimental verification, another Nobel prize was awarded to J. Steinberger, L. Lederman and M. Schwartz in 1988);
• the assumption that neutrinos, in the vacuum, may convert in another type of neutrinos, property known as neutrino oscillations (for which experimental verification a Nobel prize wad awarded to M. Koshiba in 2002).

Bruno Pontecorvo's Writings (to be completed):

• Neutron Well Logging – A New Geological Method Based on Nuclear Physics, Oil and Gas Journal, 1941, vol.40, p.32–33.1942.

Books about Bruno Pontecorvo

• M. Mafai – Il lungo freddo: Storia di Bruno Pontecorvo, lo scienziato che scelse l'URSS – Milano, 1992

External links

• Biography / Scientific Works / Popular Articles / About B. Pontecorvo / Photoalbum (in english and russian)
• 1950's news of Pontecorvo's disappearing from BBC archive