IRENE JOLIOT-CURIE, FREDERIC JOLIOT-CURIE

Spouses Joliot-Curie, deserves much credit for the study of atomic structure, especially the atomic nucleus. They made one of the greatest discoveries of the twentieth century - artificial radioactivity.

Irene Curie, daughter of the great scientists Pierre and Marie Curie, born September 12, 1897 in Paris. Initially, the girl attended a private school, but later his mother found the best way of training and education of his daughter. Along with several friends, professors of different disciplines, she organized the collective education of children. Mathematics is taught at an outstanding scientist P. Langevin, and chemistry led future Nobel laureate Jean Perrin.

After two years in a remarkable cooperative school, Irene admitted to the college Sevigny. As a result, it easily passed the entrance exams, and at seventeen became a student at the Sorbonne.

During the First World War, continuing studies, Irene also helped her mother in the organization of radiological services. To do this, she took a course in maintenance of medical radiological equipment and training of nurses.

She and the driver, and X-ray technician and laboratory assistant and a nurse. At the same time she continued to study at the Sorbonne, where he graduated in 1920. After graduation, Irene has worked as an assistant of Marie Curie at the Radium Institute. Mother and daughter shared the joys and difficulties in work, have worked together traveling, spoke at international congresses.

In 1925, Irene defended her doctoral thesis on "Investigation of the emission of X-rays of polonium. " While working at the Radium Institute, she met Frédéric Joliot, who at that time also was an assistant of Marie Curie.

Jean Frédéric Joliot was born March 19, 1900 in Paris, in a large family a prosperous merchant of iron. He was the youngest of six brothers and sisters. In 1908 the boy was learning the full board in the Lyceum Lakanal. Shortly before the end of Frederick called up for military service. Only the ending of the war saved him from the direction of the battlefield.

After graduating from high school to better prepare to enter the "Ecole de physique" in Paris, Frederic Joliot engaged in natural sciences in the Institute named after A. Lavoisier.

Having entered the "Ecole de physique", Frederick the physics under the guidance of the famous scientist P. Langevin. In 1923 he received an engineering degree and decided to first pass engineering practice in steel mills Arbed in Esch-sur-Alzette. Here again drafted into the army.

Finally in 1925, Frederick joined the Radium Institute as preparator Maria Sklodowska-Curie.

The first work carried out by Frederick, devoted to the study of electrical properties of thin metal films.

Photo — «Irene Joliot-curie, Frederic Joliot-curie»

Not only the Curie struck severity engineering young preparator. For example, the famous English physicist, Thomson has adopted a method developed by Frederick preparation of thin films of gold and in one of his articles, he expressed his gratitude.

At the Radium Institute met with Irene Joliot-Curie. October 4, 1926 in the City Hall of the fourth district of Paris was registered their marriage. Irene and Frederick now began to work together to improve the methods for obtaining strong radioactive drugs.

During his academic career Frederic published about one hundred and twenty scientific papers. Of these, more than half were satisfied with Irene.

In 1930, Frederick was awarded a doctoral degree for a study of electrochemical properties of polonium. He worked at that time improvements cloud chamber and constructed several of its varieties. Camera this couple used to measure the properties of neutron radiation.

Working under the guidance of Marie Curie, Irene and Frederic eventually became outstanding scientists. In the period from 1927 to 1932, they received a large amount of polonium, studied the properties of the so-called ray Bothe and Becker spent a lot of work to a large extent prepared the 1932 discovery of the neutron by J. Chadwick. Irene and Frederic Joliot-Curie received photos (1932), which first showed the transformation of gamma-rays, electrons and positrons.

Their performance in 1933 at the Solvay Congress in Brussels led to a lively discussion. Especially great interest in the results of the spouses Joliot-Curie demonstrated Bohr and W. Pauli. The joy of great scientific success of young scientists have managed to share with them Marie Curie. In 1934 Irene and Frederic Joliot-Curie discovered artificial radioactivity.

About how it happened, described in detail in his book, K. Manolov and V. Tyutyunnik:

"Spouses Joliot-Curie discovered that after the bombardment of alpha particles, some of the lightest elements - magnesium, boron, aluminum - emit positrons. Scientists have attempted to establish the mechanism of this emission, which differed in character from all the then known cases of nuclear transformations. They put the source of alpha particles (preparation of polonium) at a distance of 1 mm of aluminum foil and subjected it to radiation for about 10 minutes. and then placing it over the foil Geiger-Mueller, they noticed that the foil emits radiation whose intensity decreases with time in exponential dependence with a half life of 3 minutes 15 seconds. In the experiments with boron and magnesium half-lives were 14 and 2. 5 minutes respectively.

During the experiments with hydrogen, lithium, carbon, beryllium, nitrogen, oxygen, fluorine, sodium, calcium, nickel and silver, such phenomena are not observed.

Photo — «Irene Joliot-curie, Frederic Joliot-curie»

But even these negative results have allowed spouses Joliot-Curie to the conclusion that the radiation caused by the bombardment of atoms of aluminum, magnesium and boron, can not be explained by the presence of any impurities in the polonium preparation. Analysis of the radiation of boron and aluminum in a cloud chamber showed that it is a stream of positrons. It became clear that scientists are dealing with a new, radically different from all known cases of nuclear transformations. Known to the time the nuclear reactions were explosive in nature, while the emission of "positive electrons" some of the light elements which were exposed to alpha rays of polonium, continues for some more or less extended period after removal of the source of alpha rays. In the case of boron, for example, this time up to an hour.

Spouses Joliot-Curie came to the conclusion that here we are talking about most of this radioactivity appearing in the emission of a positron.

There was a lack of new evidence, and above all required to provide an appropriate radioactive isotope. Based on research of Rutherford and Cockcroft, spouses were able to determine what happens to the aluminum atoms by bombarding them with alpha particles of polonium. First, the alpha particles are trapped by the nucleus of an atom of aluminum, the positive charge which increases by two units, so that it becomes the nucleus of a radioactive phosphorus atom, called the scientists′ radiophosphorus. This process is accompanied by emission of one neutron, which is why the mass of isotope increases not four, but three units and is equal to 30. Stable isotope of phosphorus has a mass of 31. "Radiophosphorus" with a charge 15 and mass of 30 decays with a half life of 3 minutes 15 seconds, emitting a positron and turning into a stable isotope of silicon.

The sole and conclusive evidence that aluminum is transformed into phosphorous and then into silicon to charge 14 and mass 30, could only be a selection of these elements and their identification with their characteristic quality of chemical reactions. For any chemist working with persistent connections, this was a simple task, but Irene and Frederic situation was quite different: they have received phosphorus atoms existed little more than three minutes. Chemists have multiple methods of detection of this element, but they all require a lengthy definitions. Therefore, the opinion of chemists was unanimous: to identify the phosphorus in such a short time is impossible.

However, the wife Joliot-Curie did not recognize the word "impossible". Although this "unsolvable" problem demanded overwork, stress, virtuosic skill and infinite patience, it was solved. Despite the extremely low yield of the products of nuclear transformations, and an almost negligible mass of matter, which has undergone transformation, only a few million atoms, able to establish the chemical properties of radioactive phosphorus.

Photo — «Irene Joliot-curie, Frederic Joliot-curie»

On his research Irene immediately informed her mother. Highlighted in the laboratory of Maria Sklodowska-Curie, polonium has contributed to the remarkable new discovery.

The discovery of artificial radioactivity was immediately rated as one of the greatest discoveries of the century. Before that the radioactivity, which was characterized by some elements could be either caused, or destroyed, or somehow altered by humans. Spouses Joliot-Curie, the first artificially induced radioactivity, received new radioactive isotopes. Scientists foresee great theoretical significance of this discovery and its practical applications in biology and medicine. "

For this work, the wife Joliot-Curie were awarded the 1935 Nobel Prize in chemistry. Irene had once attended a ceremony of this prestigious scientific awards. Member of the Royal Swedish Academy of Sciences KV Palmayer, introducing the winners, Irene recalled the happy day when she shared in Stockholm joy to his mother. "In collaboration with your husband you are worthy continuation of its excellent tradition" - said Palmayer.

In his Nobel lecture Frederick, in particular, said: "We should not assume, though a few hundred atoms that make up our planet, were created all at once, and will exist forever. "

After the discovery of artificial radioactivity, Irene Joliot-Curie had ceased to engage in experimental work, as she had, during many years of research has received an overdose of radiation. She appeared a little more time to raise children - daughter Helen and son Pierre. In addition to performing with her husband of numerous scientific papers Irène Joliot-Curie in 1932 directed the Institute of Radium, and in 1934 became a professor at the Sorbonne. Together with the Serbian chemist Paul Savich in 1938, Irene opened one of the fission products of uranium - lanthanum.

In 1936 Irene was appointed deputy minister of national education. In this position she oversaw all research work, which took place in France.

Frederick also took the chair at the Faculty of Exact Sciences, University of Paris, as well as the Department of Nuclear Chemistry in the College de France in 1937. Here he organized a laboratory of nuclear chemistry, which investigated the processes occurring in the uranium under the influence of the neutrons. As a result, he found the possibility of obtaining very high-energy nuclear reactions.

In 1939, Frederick began work on the construction of nuclear reactor heavy water, which is patented jointly with J. Perrin. From Belgium was received on 9 tons of uranium oxide, from Norway - the whole world′s supply of heavy water - 185 pounds. However, in May 1940, the occupation of France interrupted by these fascists work.

Photo — «Irene Joliot-curie, Frederic Joliot-curie»

During the Nazi occupation of the wife remained in Paris. Frederick with the full support of his wife worked in the anti-fascist intellectuals Committee has moved nuclear preparations, scientific equipment and documentation of his institute in England. During the Nazi occupation of France Langevin he hid from the Gestapo in a safe place. In 1941, Frederic Joliot-Curie, was among the founders of the National Front for the Liberation of France. In 1942 he joined the French Communist Party, actively supported the guerrillas. In 1944, when the Gestapo came out on the trail of Frederick, he went underground, and Irene, together with their children fled to neutral Switzerland.

In the postwar years, Irene Joliot-Curie headed the Department of Physics and radioactivity in the University of Paris, combining this post with the directorship of the Institute of radium.

In 1946, Frederic Joliot-Curie was appointed head of the Atomic Energy Commission of France. Irene in 1946-1951 years helped her husband in the establishment and commissioning of the French nuclear reactor "Zoe". She also participated in the creation of the Central Institute of Nuclear Physics in Orsi.

In 1949, the couple Joliot-Curie, one of the first signed a petition on the need to convene the World Peace Council. Irene joined the World Peace Council, headed by her husband, and participated in numerous conferences and congresses of peace.

This anti-war activities did not like the French government. In 1951, Irene was not allowed to participate in the development of nuclear reactor, a year earlier Frederic Joliot-Curie was removed from his post of high commissioner for atomic energy. However, the two scientists continued their research to the benefit of mankind, and remained faithful to their political beliefs.

In the fifties, the health of Irene Joliot-Curie became dramatically worse. She died March 17, 1956 of acute leukemia.

After the death of his wife Frederick took over the leadership of the Department of Nuclear Physics at the University of Paris.

In 1958, Frederic Joliot-Curie became ill with viral hepatitis and died on August 14. In his memory, named one of the lunar craters.

F. Joliot-Curie, wrote: "The purely scientific knowledge brings peace to our souls and at the same time a strong belief in humanity′s future, driving out remnants and the fear of unseen forces. They give us confidence in a bright tomorrow, and beyond that scientific knowledge is an essential element unity of thought, of all people, scattered on the surface of our planet. "