Emilio Segrè (1905-1989)


hen Segrè, professor of physics at the University of Palermo, first visited Berkeley in 1936, he had no way of knowing how crucial the University would be in his future.

Touring the Rad Lab with Lawrence, he was struck by the artificial radioactivity created when the cyclotrons had finished their atomic bombardment. After returning to Italy, they kept in touch and in 1937 Lawrence sent Segrè a molybdenum strip from a cyclotron’s deflector which was giving off various forms of radioactivity from an unknown source. Upon analysis, Segrè discovered that the source was the first man-made element, atomic number 43, which he and a colleague called “technetium.”

In 1938, Segrè returned to the Rad Lab intending to stay for the summer, but Mussolini’s passage of new laws barring Jews from university positions made him an instant emigrant, temporarily separating him from his wife and son back home in Italy. Lawrence offered him a temporary job as a Research Associate at the rate of $300 a month, later reduced to $116.

Despite the difficulties of his personal situation, Segrè was fruitful in his work. He took part in the discoveries of two other new elements: astatine (atomic number 85) and the mysterious and fissionable plutonium (atomic number 94). At Los Alamos during World War II he worked as a group leader, later becoming an American citizen and returning to Berkeley as professor of physics.

In 1959 he received the Nobel Prize (with Owen Chamberlain) for their discovery of the anti-proton. In 1972 he returned to Italy where Parliament passed a special law giving him a chair in physics at the University of Rome.

First Man-Made Element Discovered


egrè’s analysis of a molybdenum strip from the 37” cyclotron that was emitting radiation from an unknown source led to the discovery of atomic element 43, technetium – an artificially synthesized cyclotron by-product that does not appear in nature.

Letters exchanged between Lawrence and Segrè , 1937 Letters exchanged between Lawrence and Segrè , 1937 Letters exchanged between Lawrence and Segrè , 1937
Letters exchanged between Lawrence and Segrè, 1937
from left: to Segre, to Lawrence [1, 2]
[BANC MSS 72/117, Ctn. 16:14]

A Cut in Pay



fter agreeing to pay Segrè a monthly salary of $300, Lawrence abruptly reduced it by more than 50% when he discovered Segrè was stuck in Berkeley due to the War. Segrè’s autobiography recounts his shock at Lawrence’s apparently opportunistic – at least, never explained – action.