# Emilio G. Segrè

Emilio G. Segrè
Born Emilio Gino Segrè
1 February 1905
Tivoli, Italy
Died 22 April 1989 (aged 84)
Lafayette, California, United States of America
Institutions Los Alamos National Laboratory
University of California, Berkeley
University of Palermo
University of Rome La Sapienza
Alma mater University of Rome La Sapienza
Doctoral students Basanti Dulal Nagchaudhuri
Samarendra Nath Ghoshal
Known for Discovery of the antiproton
Discovery of technetium
Discovery of astatine
Notable awards Nobel Prize in Physics (1959)
Signature

Emilio Gino Segrè (30 January 1905 – 22 April 1989) was an Italian physicist and Nobel laureate in physics, who with Owen Chamberlain, discovered antiprotons, a sub-atomic antiparticle.[1] Emigrated in the U.S. in 1938 because of the Italian Racial Laws, Segrè became a naturalized American Citizen in 1944.[2]

## Early life

Emilio Gino Segrè was born into a Sephardic Jewish family in Tivoli, near Rome, on 30 January 1905, the son of Giuseppe Segrè, a businessman who owned a paper mill, and Amelia Sussanna Treves. He had two older brothers, Angelo and Marco.[3] His uncle, Gino Segrè, was a law professor.[4] He was educated at the ginnasio in Tivoli, and, after the family moved to Rome in 1917, the ginnasio and liceo in Rome.[5] He graduated in July 1922, and enrolled in the University of Rome La Sapienza as an engineering student.[6]

In 1927, Segrè met Franco Rasetti, who introduced him to Enrico Fermi. The two young physics professors were looking for talented students. They attended the Volta Conference at Como in September 1927, where Segrè heard lectures from notable physicists including Neils Bohr, Werner Heisenberg, Robert Millikan, Wolfgang Pauli, Max Planck and Ernest Rutherford. Segrè then joined Fermi and Rasetti at their laboratory in Rome. With the help of the director of the Institute of physics, Orso Mario Corbino, Segrè was able to transfer to physics,[7] and, studying under Fermi, earned his laurea in July 1928.[8]

After a stint in the Italian Army from 1928 to 1929, during which he was a commissioned as a second lieutenant in the antiaircraft artillery,[9] Segrè returned to the laboratory on Via Panisperna. He published his first paper, which summarised his thesis "On anomalous dispersion in mercury and in lithium", jointly with Edoardo Amaldi in 1928, and another paper with him the following year on the Raman effect.[10]

In 1930, Segrè began studying the Zeeman effect in certain alkaline metals. When his progress stalled because the diffraction grating he required to continue was not available in Italy, he wrote to four laboratories elsewhere in Europe asking for assistance, and received an invitation from Pieter Zeeman to finish his work at Zeeman's laboratory in Amsterdam. Segrè was awarded a Rockefeller Foundation fellowship, and, on Fermi's advice, elected to use it to study under Otto Stern in Hamburg.[11]

Segrè was appointed assistant professor of physics at the University of Rome in 1932 and served until 1936, becoming one of Via Panisperna boys. From 1936 to 1938 he was Director of the Physics Laboratory at the University of Palermo. After a visit to Ernest O. Lawrence's Berkeley Radiation Laboratory, he was sent a molybdenum strip from the laboratory's cyclotron deflector in 1937 which was emitting anomalous forms of radioactivity. After careful chemical and theoretical analysis, Segrè was able to prove that some of the radiation was being produced by a previously unknown element, dubbed technetium, and was the first artificially synthesized chemical element which does not occur in nature.

He was a colleague and close friend of Ettore Majorana, who disappeared mysteriously in 1938.

While Segrè was on a summer visit to California in 1938, Benito Mussolini's fascist government passed anti-Semitic laws barring Jews from university positions. As a Jew, Segrè was now rendered an indefinite émigré. At the Berkeley Radiation Lab, Lawrence offered him a job as a Research Assistant—a relatively lowly position for someone who had discovered an element—for US\$300 a month. However, in Segrè's recollection, when Lawrence learned that Segrè was legally trapped in California, he reduced his salary to US\$116 a month which many, including Segrè, saw as exploiting the situation. Segrè also found work as a lecturer of the physics department at the University of California, Berkeley.

While at Berkeley, he helped discover the element astatine and the isotope plutonium-239 (which was later used to make Fat Man, the atom bomb dropped on Nagasaki). He found in April 1944 that Thin Man, the proposed plutonium "gun-type" bomb, would not work (because of the presence of Pu-240 impurities), and priority was given to Fat Man, the plutonium "implosion" bomb.

Segrè's ID badge photo from Los Alamos

From 1943 to 1946 he worked at the Los Alamos National Laboratory as a group leader for the Manhattan Project. In 1944, he became a naturalized citizen of the United States. He taught at Columbia University, University of Illinois and University of Rio de Janeiro. On his return to Berkeley in 1946, he became a professor of physics and of the history of science, serving until 1972.

Professors Emilio Segrè and Owen Chamberlain were co-heads of a research group at the Lawrence Radiation Laboratory. Their group proposed the experiment to discover the anti-proton and this was the chief reason that the Bevatron was built at LRL. The Bevatron was designed to reach proton energies of 6.2 $m_0 c^2$ where mo is the rest mass of the proton. With the new Bevatron, the Segrè/Chamberlain group produced the first anti-proton (as seen in bubble chamber pictures) and the two shared the 1959 Nobel Prize in Physics for their work.

In 1970, Segrè published a biography of Fermi (Enrico Fermi: Physicist, University of Chicago Press)

In 1974 he returned to the University of Rome as a professor of nuclear physics.

Segrè was also active as a photographer, and took many photos documenting events and people in the history of modern science. The American Institute of Physics named its photographic archive of physics history in his honor.[12] Segrè died at the age of 84 of a heart attack.

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## Notes

1. ^ Segrè, Emilio,Nuclear Properties of Antinucleons  adapted from Nobel Lecture given 11 December 1959. Science  (1960) vol 132, p 9.
2. ^ "Emilio Segrè". Jewish virtual Library.
3. ^ Segrè 1993, pp. 2-3.
4. ^ Segrè 1993, p. 6.
5. ^ Segrè 1993, pp. 22-25.
6. ^ Segrè 1993, pp. 37-38.
7. ^ Segrè 1993, pp. 44-49.
8. ^ Segrè 1993, p. 52.
9. ^ Segrè 1993, pp. 54-59.
10. ^ Segrè 1993, pp. 61, 304.
11. ^ Segrè 1993, pp. 64-70.
12. ^
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## References

• Segrè, Emilio (1993). A Mind Always in Motion: the Autobiography of Emilio Segrè. Berkeley, California: University of California Press. ISBN 0520076273. OCLC 25629433.
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