摘要
In August 1950, the nuclear physicist Bruno Pontecorvo suddenly left Rome for Stockholm and disappeared without leaving any trace. Pontecorvo had joined the British atomic bomb project. His abrupt disappearance quickly became an international affaire, causing much concern to the western intelligence services, who were worried about the escape of atomic secrets to the Soviet Union, especially after Fuchs＇ famous case. In the Union of Soviet Socialist Republics （USSR）, Pontecorvo was welcomed with honour, but also isolated from the rest of the world for many decades. He always denied any direct involvement in the Soviet nuclear programme. According to him, he moved to Russia because of his socialist beliefs, working only on particle physics and peaceful applications of atomic energy. Who was really Bruno Pontecorvo？ A pacifist like Robert Oppenheimer or a communist agent like Klaus Fuchs？ Did he have access to any information about the Manhattan Project during the war, thanks to his friendship with Enrico Fermi？ Did he spy on the Anglo-Canadian programme like Igor Gouzenko, before moving to Russia？ Did he join Soviet military projects across more than 30 years in Dubna？ The author will discuss how the perception of Pontecorvo＇s case changed in the public opinion from the 1950s until the 1990s, as a mirror of the tensions between the two blocks. The whole affaire was object of harsh political confrontation in Italy for almost 50 years. Therefore, the author will also focus on the role played by the Italian communists in Pontecorvo＇s defection to the USSR as well as on such a local debate, which reflects the history of the post-war Italian Communist Party （PCI） until the end of the Cold War.
