Fermi (Fermi), Enrico( Italian-American physicist, Nobel Prize in Physics, 1938)
Comments for Fermi (Fermi), Enrico
Biography Fermi (Fermi), Enrico
September 29, 1901, Mr.. - November 30, 1954
Italian-American physicist Enrico Fermi was born in Rome. He was the youngest of three children of a railroad employee, Alberta Fermi nee Ida de Gattis, a teacher. Even as a child F. found great abilities in mathematics and physics. His outstanding knowledge in these sciences, acquired largely through self-education, allowed him to get in 1918. scholarship and enroll in higher normal school at the University of Pisa. Even four years later, in 1922, F. received his doctorate in physics with honors for his work on the pilot study of X-rays.
Upon his return to Rome F. received from the Italian Government Scholarship, . enabled him to continue the study of modern physics in Germany, . by Max Born, . then headed by branch of Theoretical Physics, University of Gottingen, . in Holland, . by Paul Ehrenfest in Leiden University,
. Ehrenfest supported the young F.
In 1924, Mr.. F. began to read lectures on mathematical physics and mechanics at the University of Florence. In the early years of his study addresses the problem of general relativity, Albert Einstein, statistical mechanics, quantum theory and the theory of electrons in solids. In 1926, Mr.. they have developed a new kind of statistical mechanics, the principles of the ban prompted Wolfgang Pauli. It is possible to successfully describe the behavior of electrons, and later was applied to the protons and neutrons. Statistic F. allowed a better understanding of the electrical conductivity of metals and led to a more effective model of the atom.
When the University of Rome in 1927. established the first chair of theoretical physics, FA, who had managed to gain international prestige, was elected its head. In Rome, EF. rallied around a few prominent scientists and founded the first school in Italy of modern physics. In the international scientific community began to call her group the Fermi. Two years later, F. Benito Mussolini was appointed to the post of honorary member of the newly established Royal Academy of Italy.
In the early 30-ies. F. moved its focus from the outer electrons of an atom in the atomic nucleus. In 1933. He proposed the theory of beta decay, may explain how the nucleus spontaneously emits electrons and the role of neutrino particles, devoid of electric charge and not to fall while the experimental detection. The existence of such particles was postulated by Pauli, and the name coined by EF. (The neutrino was experimentally detected in 1956). The theory of beta decay F. touched a new type of force, known as the weak interaction. These forces act between neutrons and protons in the nucleus and determine the beta decay, by the intensity of the weak interaction is much inferior to the strong, held together by the nucleons - the particles that make up the core. Article V. of beta decay has been rejected because of its novelty by the British magazine 'Neicho', but published in Italian and in German magazines. Based on the expressed EF. ideas, Hideki Yukawa predicted in 1935. existence of a new elementary particle, now known under the name of pi-meson, or pion.
In the 20-ies. was assumed that the atom contains two types of charged particles: the negative electrons that orbit around the nucleus of positive protons. Physicists interested in whether the nucleus containing particles devoid of electric charge. Experiments on the detection of electrically neutral particles culminated in 1932 when James Chadwick discovered the neutron, in which physicists, especially Werner Heisenberg, almost immediately recognized nuclear partner of the proton. F. appreciated the value of the neutron as a powerful tool to initiate nuclear reactions. The experimenters attempted to bombard the atoms of charged particles, but to overcome the electrical repulsion of the charged particles must be dispersed on powerful and expensive accelerators. Incident electrons are repelled by atomic electrons, protons and alpha particles - the nucleus like electrical charges repel each other with the same name. Since the neutron has no electric charge, eliminating the need for accelerators.
Significant progress was made in 1934, when Frederic Joliot and Irene Joliot-Curie discovered artificial radioactivity. By bombarding the nucleus of boron and aluminum with alpha particles, they first created a new radioactive isotopes of known elements. Continuing the work begun by these studies, F. and his staff in Rome began to bombard with neutrons each element of the periodic table in the hope of new radioactive isotopes with the accession of neutrons to the nuclei. First success was achieved in the bombardment of fluorine. Methodologically bombarding all the heavier elements, F. and his team have received hundreds of new radioactive isotopes. The bombardment of uranium - 92-th element, the heaviest naturally occurring, they have a complex mixture of isotopes. The chemical analysis did not find it either uranium isotopes or isotopes of neighboring elements (indeed, the analysis excluded the presence of all elements with indices from 86 to 91). There is a suspicion that the experimenters for the first time managed to get a new artificial element with atomic number 93. To the displeasure of AF, the laboratory director Orso Corbino, without waiting for check assays, announced the successful synthesis of the 93rd element. In fact, F. could not get it. But he, without knowing it, caused the fission of uranium, a heavy nucleus splits into two or more fragments and other fragments. Fission of uranium was discovered in 1938. Otto Hahn, Lise Meitner and Fritz Strassmann.
In 1935, several months after the start of experiments, F. and his collaborators found that if the neutrons are slowed by passing through water and paraffin, they are more effectively initiate the nuclear reactions. Slowing down of neutrons due to their collisions with hydrogen nuclei (protons) in large quantities contained in these environments. Collisions of neutrons and protons is a significant part of the neutron energy is lost as the masses of these particles are almost equal. Equally large energy transfer occurs in collisions of billiard balls with equal masses.
Meanwhile, in Italy's growing strength gained fascist dictatorship of Mussolini. In 1935. Italian aggression against Ethiopia led to economic sanctions by the members of the League of Nations, and in 1936. Italy formed an alliance with Nazi Germany. Group F. at the University of Rome began to fall apart. After the Italian government in September 1938. Semitic civil laws F. and his wife, a Jew by birth, decided to emigrate to the U.S.. Accepting the invitation from Columbia University to take a position as professor of physics, F. informed the Italian authorities that he went to America for six months.
In 1938. F. was awarded the Nobel Prize in Physics. The decision of the Nobel Committee said that the prize awarded to F. 'for proving the existence of new radioactive elements obtained by neutron irradiation, and the resulting discovery of nuclear reactions induced by slow neutrons'. 'Along with the outstanding discoveries F. general recognition of his art of the experimenter, amazing ingenuity and intuition ... will shed new light on the structure of the nucleus and open new horizons for the future development of atomic research '- said, introducing the winner, Hans Pleyel from the Royal Swedish Academy of Sciences.
. During the award ceremony, held in December, 1938
. Stockholm, S. shook hands with the King of Sweden, instead of welcoming to the Nazi salute, for which he was attacked in the Italian press. Immediately after the festivities F. went overseas. Upon arrival in the United States, FM, like all immigrants of that time, had to pass a test to check the mental abilities. Nobel laureate was asked to lay down 15 and 27 and section 29 2.
Shortly after the family F. landed in New York in the United States arrived from Copenhagen, Niels Bohr, to spend several months at the Princeton Institute for Basic Research. Boron reported the discovery by Hahn, Meitner and Strassmann split the uranium by bombarding it with neutrons. Many physicists have started to discuss the possibility of chain reaction. If every time a neutron splits an atom of uranium emitted neutrons are new, they might, when confronted with other atoms of uranium, to produce new neutrons and thus cause a sustained chain reaction. Since each fission of uranium released large amounts of energy, the chain reaction could be accompanied by a huge release of. If it were possible to 'curb' chain reaction, the uranium would be unheard of explosive force, in order to implement a chain reaction of F. begun planning experiments that would determine whether such a reaction and whether it is controllable.
The negotiations with the Office of the Navy in 1939. F. first mentioned the possibility of creating nuclear weapons on the basis of a chain reaction with a powerful energy release. He received federal funding to continue their studies. In the course of V. and the Italian physicist Emilio Segre, his former student, set to use as a 'bomb' for the atomic bomb was not yet open the element plutonium. Although plutonium (Pu), the element with atomic number 94, was not yet known, the two scientists were convinced that an element with mass number 239 (239Pu) should be split and can be obtained in a uranium reactor with neutron capture by uranium-238.
. In 1942, . when the U.S. Manhattan Project was created to work on the atomic bomb, . responsibility for the investigation of a chain reaction and obtain plutonium was assigned to the F., . which took from a legal point of view of the status of 'foreigner - citizen of hostile powers',
. The following year, research was moved from Columbia to the University of Chicago, where F. as chairman of the subsection of the theoretical aspects of the Uranium Committee, oversaw the creation of the world's first nuclear reactor, which was built on the site for the game of squash under the stands of the university football stadium, Stagg Field.
. Erected the reactor at the technical jargon, called 'heap', as it was built of slabs of graphite (pure carbon), which should contain the rate of chain reaction (slow neutrons)
. Uranium and uranium oxide were placed between graphite sticks. December 2, 1942, Mr.. cadmium control rods that absorb neutrons, were slowly advanced to run the world's first self-sustaining chain reaction. 'It was clear - he wrote later John Cockcroft - that F. opened the door to the atomic age '. Somewhat later, F. was appointed head of the department of modern physics in the new laboratory, established under the leadership of Robert Oppenheimer to build the atomic bomb in the highly classified town of Los Alamos (New Mexico). F. and his family became citizens of the United States in July 1944, and next month they moved to Los Alamos. F. witnessed the first atomic bomb explosion July 16, 1945, Mr.. near Alamogordo (New Mexico). In August 1945,. atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki.
At the end of the war F. returned to the University of Chicago, to take the post of professor of physics and become a member of the newly created at the University of Chicago Institute for Nuclear Research. F. was a great teacher and renowned as an unsurpassed lecturer. Among his students include Murray Gell-Mann, Chen Ning Yang, Tsung-Dao Lee and Owen Chamberlain. Upon completion in 1945. Chicago construction cyclotron (particle accelerator) F. began experiments to study the interaction between just before open pi-mesons and neutrons. F. belongs also to the theoretical explanation of the origin of cosmic rays and their source of high energy.
In 1928, Mr.. F. married Laura Capone, who belonged to the well-known Jewish family in Rome. At spouses Fermi son and a daughter. A man of outstanding intellect and boundless energy, F. fond of mountaineering, winter sports and tennis. He died of stomach cancer at his home in Chicago shortly after he was fifty-three years. The following year, in honor of his new, 100-th element has been named the farm.
F. was elected a member of the National Academy of Sciences USA (1945), an honorary member of the Royal Society of Edinburgh (1949) and a foreign member of the Royal Society of London (1950). U.S. President F. was appointed a member of the General Advisory Committee of the Atomic Energy Commission (1946 ... 1950). He was vice-president (1952) and president (1953) American Physical Society. In addition to the Nobel Prize, F. was awarded a gold medal Matteuchchi National Academy of Sciences of Italy (1926), . Hughes medal of the Royal Society of London (1943), . Civilian Medals of Merit of the Government of the United States of America (1946), . Medals Franklinovskogo Franklin Institute (1947), . Barnard's gold medal for outstanding academic achievements at Columbia University (1950) and the first prize of the Fermi, . awarded by the Commission for Atomic Energy of the United States of America (1954),
. He was an honorary doctor of many universities, including Washington and Yale universities, Rokfordskogo College. Harvard and the University of Rochester.