Emilio Segrè

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Tivoli, Italy
Birth Sign
Tivoli, Italy

Emilio Gino Segrè was an Italian-American physicist who was well-known in his field. In 1959, he and American physicist Owen Chamberlain shared the Nobel Prize in Physics for their discovery of the antiproton, a subatomic antiparticle with the same mass as a proton but the opposite electrical charge. He worked as an assistant professor of physics at the ‘University of Rome’ before becoming one of the Via Panisperna lads. He worked as the Director of the Physics Laboratory at the ‘University of Palermo’ for a few years. Following his visit to the ‘Berkeley Radiation Laboratory’ in Berkeley, California, he was delivered a molybdenum strip from the lab’s cyclotron deflector, which was emitting an unusual sort of radioactivity. Segrè undertook a detailed investigation and determined that a portion of the radiation was produced by a newly discovered chemical element known as technetium, which was made artificially. He joined the ‘Berkeley Radiation Laboratory’ as a Research Assistant after being fired from the ‘University of Palermo’ by Benito Mussolini’s fascist administration, which implemented anti-Semitic legislation prohibiting Jews from holding university jobs. He contributed to the discovery of the astatine element and the plutonium-239 isotope, both of which were used in the building of the Fat Man atomic bomb, which was dropped on Nagasaki, Japan. From 1943 until 1946, he was the director of the ‘Manhattan Project’ at the ‘Los Alamos National Laboratory.’ Meanwhile, he became a naturalized American citizen in 1944. He then spent almost two decades as a professor of physics and science history at the ‘University of California’, Berkeley.

Childhood and Adolescence

He was born on February 1, 1905, in Tivoli, Italy, to Giuseppe Segrè and Amelia Susanna Treves, as the youngest of their three sons. His father was the proprietor of a paper mill.

He went at Tivoli ginnasio and then Rome ginnasio and liceo after the family moved to Rome in 1917.
He graduated from Ginnasio Mamiani in Rome in July 1922.

He then enrolled at the ‘University of Rome La Sapienza’ to pursue a degree in engineering.
He met physics professors Enrico Fermi and Franco Rasetti in 1927, who was looking for bright students. In September 1927, Segrè visited the Volta Conference in Como, where he heard lectures from famous physicists.

He transferred to physics with the support of Orso Mario Corbino, director of the Institute of Physics at the ‘University of Rome La Sapienza’. He became a member of Enrico Fermi’s group, which included prominent pupils like Ettore Majorana and Edoardo Amaldi. The group was quickly dubbed the “Via Panisperna Boys,” after the street where the physics institute was located.

Working under Fermi, he received a laurea degree in July 1928 after presenting a thesis on ‘Anomalous Dispersion and Magnetic Rotation.’
He was a second lieutenant in the Italian Army’s anti-aircraft artillery from 1928 to 1929.

In 1928, Segrè and Edoardo Amaldi released a paper titled “On anomalous dispersion in mercury and lithium,” then in 1929, they published a paper on the Raman Effect.

With Fermi’s help, he was awarded a Rockefeller Foundation fellowship and opted to study in Hamburg, Germany, under German scientist Otto Stern.

Career of Emilio Segrè

He was named assistant professor of physics at the ‘University of Rome’ in 1932, a position he held until 1936.
In 1936, he became a professor of physics at the ‘University of Palermo,’ where he also served as the director of the Physics Institute. He went to the ‘Berkeley Radiation Laboratory,’ which was created by prominent American nuclear physicist Ernest O. Lawrence, the same year. He met several American scientists there, including Franz Kurie and Edwin McMillan. He was enthralled by the radioactive scrap metal that had been utilized in the lab’s particle accelerator, the cyclotron, which Lawrence had found.

Lawrence sent him a molybdenum cyclotron deflector strip from the ‘Berkeley Radiation Laboratory’ in February 1937. It was emitting strange radiation. Segrè and mineralogist Carlo Perrier did an extensive theoretical and chemical study, proving that a portion of the radiation was generated by a chemical element that had been chemically synthesized, so discovering the first such element was not found naturally. In 1947, it was given the name technetium.

Segrè was removed from the ‘University of Palermo’ after Benito Mussolini’s fascist regime passed anti-Semitic laws prohibiting Jews from holding university positions.

He accepted Lawrence’s offer to work as a research assistant at the ‘Berkeley Radiation Laboratory.’ Together with Glenn Seaborg, he discovered the metastable isotope technetium-99m, which is now used in roughly 10 million medical diagnostic tests each year.

He discovered the neutron-absorbing nuclear toxin xenon-135 in collaboration with Chien-Shiung Wu and Alexander Langsdorf, Jr., which has a significant impact on nuclear reactor operation. He and Kenneth Ross MacKenzie were successful in isolating a new element, astatine, which is now recognized.

In December 1940, he developed plutonium-239, a main fissile isotope used in the creation of nuclear weapons, in the lab’s 60-inch cyclotron with Edwin McMillan, Arthur C. Wahl, Joseph W. Kennedy, and Glenn Seaborg.

As a result of the Japanese attack on Pearl Harbor on December 7, 1941, the United States entered the Second World War, and the United States declared war on Italy on December 11, Segrè was designated as an enemy alien. His parents were cut off from his life, and he was sent to instruct children. He formed strong bonds with many of his students during this time, notably Clyde Wiegand and Owen Chamberlain.

He worked at the ‘Manhattan Project’ at the ‘Los Alamos National Laboratory’ from 1943 to 1946. He was the head of the lab’s P-5 (Radioactivity) Group. For security reasons, he was given the alias Earl Seaman. His team was given the task of measuring and documenting the radioactivity of various fission products.

He determined in April 1944 that the proposed plutonium gun-type nuclear weapon, dubbed ‘Thin Man,’ would not work due to the presence of plutonium-240 impurities.

R-4, the Segrè group at the time, was tasked with measuring gamma radiation from the US Army’s Trinity nuclear test on July 16, 1945.

In early 1946, he returned to Berkeley and accepted a position as Professor of Physics at the ‘University of California.’ After that, he went to the ‘University of Illinois’ in Urbana–Champaign, where he worked for a few years until returning to the ‘University of California’ in Berkeley in 1952.

On September 21, 1955, he discovered antiprotons alongside Chamberlain, Ypsilantis, and Wiegand using the bevatron, a particle accelerator at the Berkeley Lab.

He served on the ‘University of California’ Berkeley Budget Committee from 1961 to 1965, and was chairman of the Physics Department from 1965 to 1966. In 1972, he attained the university’s mandatory retirement age. He continued to teach physics history after he retired.

He worked as a professor of nuclear physics at the ‘University of Rome’ for a year starting in 1974.
‘Experimental Nuclear Physics’ (1953); ‘Nuclei and Particles’ (1964); and a biography, ‘Enrico Fermi: Physicist’ (1970), are only a few of his works.

Personal History and Legacy

He married Elfriede Spiro, a Jewish woman from West Prussia who moved to Italy after Hitler’s ascension to power in Germany in 1933, on February 2, 1936.
Claudio and Amelia Gertrude Allegra were born in 1937, and Fausta Irene was born in 1945, among their three children.

Following Elfriede’s death in October 1970, he married Rosa Mines in February 1972.
He died of a heart attack on April 22, 1989, in Lafayette, California, and was buried in Lafayette Cemetery.

Estimated Net Worth

The estimated net worth of Emilio Segrè is unknown.


He was an avid photographer, and after his death, many of his images documenting events and personalities in the history of contemporary science were donated to the ‘American Institute of Physics.’ In his honor, the institute’s picture archive of physics history is named after him.