Bruno Pontecorvo; Nuclear Scientist Defected to Soviets

Italian physicist Bruno Pontecorvo, a pioneer in the study of subatomic particles who defected to the Soviet Union, has died. He was 80.

Italian news reports said he died Friday of pneumonia in Dubna, a city outside Moscow, where he directed a high-energy physics laboratory.

When Pontecorvo disappeared from view in 1950, it prompted fears in the West that he was taking atomic secrets to the Soviet Union.

But when he returned to his native land for the first time since 1950, on a 1978 visit, he denied engaging in espionage or ever working on atomic or hydrogen bombs.

“I am a peaceful man,” he said, adding that his move to Moscow was a political choice. He obtained Soviet citizenship in 1952 and joined the Communist Party three years later.

At the beginning of his career, Pontecorvo was one of the group of brilliant young physicists who worked with Enrico Fermi in Rome in the mid-1930s.

A Jew, he fled anti-Semitism in Italy under Mussolini and then the Nazis in Paris, rejoining Fermi in the United States. He moved to Britain in 1949.

Pontecorvo disappeared while on vacation in Italy in 1950. He turned up publicly for the first time in the Soviet Union in 1955, signing an appeal to nuclear scientists to avoid working on military projects.

Two former colleagues, Klaus Fuchs in Britain and Alan Nunn May in Canada, were convicted of espionage in 1950 and 1946, respectively.

Pontecorvo said he feared persecution in those years because of his association with them; his opponents said increased surveillance prevented him from passing on information to the Soviets. The physicist was never formally accused of espionage.