Segre, Emilio( Italian-American physicist, Nobel Prize in Physics, 1959)
Comments for Segre, Emilio
Biography Segre, Emilio
February 1, 1905, Mr.. - April 22, 1989
Italian-American physicist Emilio Gino Segre was born in Tivoli, a small town near Rome, and was one of three sons of industrialist Giuseppe Segre and Amelia (nee Treves), Segre. Emilio first was in elementary school in Tivoli, secondary education completed in the Roman Lyceum Mamiani in 1922. Prior to study physics, the interest in which C. manifested in childhood, he had five years to study at the College of Engineering, University of Rome. Go to specialization in physics took place partly under the influence of teaching in the Physics Department at the time of Enrico Fermi. S. and Fermi become close friends and colleagues, and doctoral dissertation with. Physics (1928) was successfully defended under the direction of the Fermi level.
After graduating with. is a four-year compulsory military service in the Italian Army as an artillery officer, then returned to the University of Rome to the post of instructor in physics. Getting a Rockefeller Foundation scholarship enabled him to work with Otto Stern in Hamburg and Pieter Zeeman in Amsterdam. Then C. is Associate Professor at the Department of Fermi.
Initially, before serving in the army, C. involved in atomic spectroscopy, molecular beams and X-rays. He carried out important research in the field of spectroscopy of forbidden lines and the Zeeman effect and Stark. Zeeman effect is the splitting of the lines in an external magnetic field into several components. In the Stark effect (named in honor of Johannes Stark) splitting of the lines occurs under an electric field.
Later On. begins to wonder Nuclear Physics. However, Fermi and other colleagues, he became a pioneer in the field of neutron physics. With the Fermi irradiated with neutrons many different materials. In 1935. She was slow neutrons whose velocity decreased as a result of collisions with light nuclei. Later slow neutrons have played an important role in the production of nuclear energy: the target nucleus captures slow neutrons are more likely than fast neutrons, and are more likely to undergo a nuclear reaction.
In 1936, Mr.. S. appointed dean of the Faculty of Physics University of Palermo. In the same year, he does his first visit to the United States, where he worked on the cyclotron at the University of California at Berkeley. For some time he tries to find the undiscovered elements with atomic numbers 43 (43 protons in the nucleus) - a gap in the periodic table between molybdenum (42) and ruthenium (44). At Berkeley, Ernest O. Lawrence gave C. molybdenum sample irradiated by deuterons (nuclei of hydrogen with one neutron, added to the proton). Upon his return to Italy with. and his colleagues exposed a sample to careful chemical analysis. Their work was crowned with success: they were able to identify traces of the element with atomic number 43. S. called him a technetium from the Greek technetos (artificial) because it was the first element, the resulting artificially. Technetium, be a valuable therapeutic drug in medicine, is not found in its natural form on earth, but it was detected by spectroscopic methods in the stars.
His second visit to Berkeley. deals in 1938. In cooperation with Dale R. Corson and K.R. Mackenzie, he synthesizes an artificial element with atomic number 85 (thus filling another gap in the periodic table of elements), which was named astatine. In 1940. S. with corruptible T. Seaborg and other staff opens a plutonium-239 (with atomic number 94).
Summer 1938. Italian Government takes anti-Semitic laws on civil rights, and S., who is Jewish and longtime opponent of the regime decides to stay in the United States. As an assistant researcher in the Radiation Laboratory at Berkeley. continued research of artificial radioactivity and nuclear isomorphism (the existence of nuclei with one and the same number of protons and neutrons, but are in different energy compounds, and therefore have different nuclear properties). Working with Seaborg, C. developing an effective chemical method of separation of nuclear isomers. In 1944, Mr.. He received U.S. citizenship.
Discovery of plutonium-239 has led to unintended consequences, as a new element was a splitting. Since 1944. were synthesized large quantities of plutonium. That plutonium has become the main source of energy in the atomic bomb dropped in August 1945. in Nagasaki (Japan). Following the war, during which C. was chief of the Los Alamos Laboratory of the Manhattan Project (the top-secret organization, whose mission was to create the atomic bomb), he returned to Berkeley as a full (real) Professor. His subsequent research on elementary particle physics, conducted with his usual pace, have earned him a deserved reputation as one of the pioneers of modern physics as in the field of theory and experiment in the field.
In the early 50-ies. S. begins to cooperate with Owen Chamberlain, . seeking to obtain and detect a new particle antiproton, . whose existence was predicted theoretically (antiproton - negatively charged analog of the positively charged proton, . and the other has the opposite properties),
. More than 20 years before P.A.M. Dirac, based on the mathematical symmetry of the relativistic quantum theory, predicted the existence of the positron - a positively charged analogue of the well-known electron. In 1932, Mr.. Karl D. Anderson reported the discovery of this particle in cosmic rays - high-energy radiation from extraterrestrial sources. Opening Anderson stimulated search for other antiparticles. Using the calculated to the corresponding energy accelerators, physicists have found that for the meson (a particle with mass intermediate between electron and proton masses) there is an analog - antimezon. However, the energy of existing accelerators was not enough for the birth of the antiproton.
These energies have become available after the construction bevatron (accelerator, able to disperse the particles to energies of billions of electron volts) in Berkeley. Bevatron was designed in part as per the experiments with antiprotons. S., Chamberlain, and their colleagues, using bevatron, broke up protons to energies of 6.2 billion. electron-volts and sent them to the copper atoms. It is argued, at this energy must be produced antiprotons. Physicists expect, . that antiprotons will be produced relatively rare, . be very short-lived (as antiprotons almost immediately be in contact with the protons and annihilate) and detect them among a large number of other subatomic particles, . generated by high-energy collisions, . be extremely difficult.,
. A major accomplishment S., Chamberlain and their staff was the development of an ingenious method of detecting and unambiguously identifying the particles, previously eluded researchers
. Experimenters used a complex system of magnets and magnetic devices for focusing the allocation of particles with mass, predicted by theory, a negative charge and a certain speed. Electronic counters and timers allow the passage of particles timed a predetermined distance. Finally, photo-sensitive allows to record the annihilation of protons and antiprotons for the final confirmation. To prevent erroneous results experimenters used different means. Acts of annihilation generate star-shaped tracks, which show that the incident antiprotons colliding with protons, disappear, and one act of annihilation comes about five mesons.
. After accumulating enough conclusive data, scientists in 1955
. announced the experimental confirmation of the existence of the antiproton. The experiment also showed that antiprotons are not born alone, in pairs and proton - antiproton (just as the positrons are produced in the electron-positron pairs).
In 1959, Mr.. S. and Chamberlain were awarded the Nobel Prize in Physics "for his discovery of the antiproton '. As a result of their work, said at the award ceremony, Eric HultцLn, a member of the Royal Swedish Academy of Sciences, 'now there is nothing that would have known better and clearer than the process of pair formation and annihilation. "
. After receiving the Nobel Prize with
. continued his research in elementary particle physics at Berkeley until his retirement in 1972. Two years later, his work was completed the appointment of Professor of Nuclear Physics, University of Rome, and in 1975. - Professor Emeritus at the same university.
In 1936, Mr.. S. married Elfriede Spiro. In the couple had three children: a son and two daughters. Wife C. died in 1970. Two years later he entered into a second marriage with Rosa Minee. S. was a talented popularizer of physics, producing biographical research 'Enrico Fermi, the physicist' ( 'Enrico Fermi, Physicist', 1970) and several other books. He was an avid fisherman and mountain climber.
With. received the Medal of August Wilhelm von Hoffman Germanskogo Chemical Society (1958) and Stanislao Cannizzaro prize of the Italian National Academy of Sciences (1958), as well as other awards. He was a member of the U.S. National Academy of Sciences, . Italian National Academy of Sciences, . American Philosophical Society, . American and Italian Physical Society, . American Academy of Arts and Sciences, . Indian Academy of Sciences, . Heidelberg Academy of Sciences, . Uruguay scientific community and the National Academy of Sciences of Peru,
. He was awarded honorary degrees by universities of Palermo, San Marco (Lima), and Tel-Aviv, Gustavus Adolphus College.