crème de la crème

Jai Ganesh · Yesterday 00:03:41

2464) Edwin McMillan

Gist:

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The heaviest element existing in nature is uranium, which has an atomic number of 92. All of the heavier elements are radioactive and quickly decay. It has become apparent, however, that they can be created by bombarding atoms with particles and atomic nuclei. In 1940 Edwin McMillan used a particle accelerator to radiate uranium with neutrons and proved that an element with an atomic number of 93 had been created. It was named neptunium. McMillan also contributed to the mapping of additional heavy elements and isotopes.

Summary

Edwin Mattison McMillan (September 18, 1907 – September 7, 1991) was an American physicist credited with being the first to produce a transuranium element, neptunium. For this, he shared the 1951 Nobel Prize in Chemistry with Glenn Seaborg.

A graduate of California Institute of Technology, he earned his doctorate from Princeton University in 1933, and joined the Berkeley Radiation Laboratory where he discovered oxygen-15 and beryllium-10. During World War II, he worked on microwave radar at the MIT Radiation Laboratory, and then on sonar at the Navy Radio and Sound Laboratory. In 1942 he joined the Manhattan Project, the wartime effort to create atomic bombs, and helped establish its Los Alamos Laboratory where the bombs were designed. He led teams working on the gun-type nuclear weapon design, and also participated in the development of the implosion-type nuclear weapon.

McMillan co-invented the synchrotron with Vladimir Veksler, and after the war he returned to the Berkeley Radiation Laboratory to build them. He was appointed associate director of the Radiation Laboratory in 1954 and promoted to deputy director in 1958. He became director upon the death of lab founder Ernest Lawrence later that year, and remained director until his retirement in 1973.

Details

Edwin Mattison McMillan (born September 18, 1907, Redondo Beach, California, U.S.—died September 7, 1991, El Cerrito, California) was an American nuclear physicist who shared the Nobel Prize for Chemistry in 1951 with Glenn T. Seaborg for his discovery of element 93, neptunium, the first element heavier than uranium, thus called a transuranium element.

McMillan was educated at the California Institute of Technology and at Princeton University, where he earned a Ph.D. in 1932. He then joined the faculty of the University of California, Berkeley, and became a full professor in 1946 and director of the Lawrence Radiation Laboratory in 1958. He retired in 1973.

While studying nuclear fission, McMillan discovered neptunium, a decay product of uranium-239. In 1940, in collaboration with Philip H. Abelson, he isolated the new element and obtained final proof of his discovery. Neptunium was the first of a host of transuranium elements that provide important nuclear fuels and contributed greatly to the knowledge of chemistry and nuclear theory. During World War II McMillan also did research on radar and sonar and worked on the first atomic bomb. He served as a member of the General Advisory Committee to the U.S. Atomic Energy Commission from 1954 to 1958.

McMillan also made a major advance in the development of Ernest Lawrence’s cyclotron, which in the early 1940s had run up against its theoretical limit. Accelerated in an ever-widening spiral by synchronized electrical pulses, atomic particles in a cyclotron are unable to attain a velocity beyond a certain point, as a relativistic mass increase tends to put them out of step with the pulses. In 1945, independently of the Russian physicist Vladimir I. Veksler, McMillan found a way of maintaining synchronization for indefinite speeds. He coined the name synchrocyclotron for accelerators using this principle. McMillan was chairman of the National Academy of Sciences from 1968 to 1971.

Jai Ganesh · Today 00:24:56

2465) Glenn Theodore Seaborg

Gist:

Work

The heaviest element existing in nature is uranium, which has an atomic number of 92. All of the heavier elements are radioactive and quickly decay. It has become apparent, however, that they can be created by bombarding atoms with particles and atomic nuclei. After initial contributions by Edwin McMillan, Glenn Seaborg succeeded in 1940 in creating an element with an atomic number of 94, which was named plutonium. This new substance became significant for both nuclear weapons and nuclear energy. Seaborg subsequently identified additional heavy elements and their isotopes.

Summary

Glenn Theodore Seaborg (April 19, 1912 – February 25, 1999) was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry. His work in this area also led to his development of the actinide concept and the arrangement of the actinide series in the periodic table of the elements.

Seaborg spent most of his career as an educator and research scientist at the University of California, Berkeley, serving as a professor, and, between 1958 and 1961, as the university's second chancellor. He advised ten US presidents—from Harry S. Truman to Bill Clinton—on nuclear policy and was Chairman of the United States Atomic Energy Commission from 1961 to 1971, where he pushed for commercial nuclear energy and the peaceful applications of nuclear science. Throughout his career, Seaborg worked for arms control. He was a signatory to the Franck Report and contributed to the Limited Test Ban Treaty, the Nuclear Non-Proliferation Treaty and the Comprehensive Test Ban Treaty. He was a well-known advocate of science education and federal funding for pure research. Toward the end of the Eisenhower administration, he was the principal author of the Seaborg Report on academic science, and, as a member of President Ronald Reagan's National Commission on Excellence in Education, he was a key contributor to its 1983 report "A Nation at Risk".

Seaborg was the principal or co-discoverer of ten elements: plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium and element 106, then called unnilhexium, which while he was still living, was named seaborgium in his honor. He said about this naming, "This is the greatest honor ever bestowed upon me—even better, I think, than winning the Nobel Prize. Future students of chemistry, in learning about the periodic table, may have reason to ask why the element was named for me, and thereby learn more about my work." He also discovered more than 100 isotopes of transuranium elements and is credited with important contributions to the chemistry of plutonium, originally as part of the Manhattan Project where he developed the extraction process used to isolate the plutonium fuel for the implosion-type atomic bomb. Early in his career, he was a pioneer in nuclear medicine and discovered isotopes of elements with important applications in the diagnosis and treatment of diseases, including iodine-131, which is used in the treatment of thyroid disease. In addition to his theoretical work in the development of the actinide concept, which placed the actinide series beneath the lanthanide series on the periodic table, he postulated the existence of super-heavy elements in the transactinide and superactinide series.

After sharing the 1951 Nobel Prize in Chemistry with Edwin McMillan, he received approximately 50 honorary doctorates and numerous other awards and honors. The list of things named after Seaborg ranges from the chemical element seaborgium to the asteroid 4856 Seaborg. He was the author of numerous books and 500 journal articles, often in collaboration with others. He was once listed in the Guinness Book of World Records as the person with the longest entry in Who's Who in America.

Details

Glenn T. Seaborg (born April 19, 1912, Ishpeming, Michigan, U.S.—died February 25, 1999, Lafayette, California) was an American nuclear chemist best known for his work on isolating and identifying transuranium elements (those heavier than uranium). He shared the 1951 Nobel Prize for Chemistry with Edwin Mattison McMillan for their independent discoveries of transuranium elements. Seaborgium was named in his honor, making him the first person for whom a chemical element was named during his lifetime.

Seaborg learned Swedish from his immigrant mother before he learned English. When he was 10, his family moved to a suburb of Los Angeles. He received a bachelor’s degree (1934) from the University of California, Los Angeles, and a doctorate (1937) from the University of California, Berkeley. He stayed on at Berkeley as the personal laboratory assistant of Gilbert N. Lewis from 1937 to 1939. He also collaborated at Berkeley with physicist Jack Livingood to isolate a number of radioactive isotopes, including iodine-131, which later saved his mother’s life and is now used for the diagnosis and treatment of thyroid disorders. At Berkeley he was, successively, research associate, instructor, and assistant professor (1937–45), becoming professor of chemistry in 1946. He served as Berkeley’s chancellor from 1958 to 1961.

Seaborg, together with Arthur C. Wahl and Joseph W. Kennedy, produced and identified the second known transuranium element, plutonium (atomic number 94), on February 23, 1941, in Room 307 of Gilman Hall, which is now a National Historic Landmark. (McMillan had discovered the first transuranium element, neptunium [atomic number 93], the previous year at Berkeley.) In addition to plutonium, best known for its use as a fuel in certain types of nuclear reactors and as an ingredient in some nuclear weapons, Seaborg and his coworkers discovered nine more new elements (atomic numbers 95–102 and 106) between 1941 and 1955.

The early studies of plutonium were carried out on a tracer scale with amounts too small to be weighed. The first visible amount of plutonium (about a millionth of a gram of plutonium fluoride) was isolated by Seaborg, Burris B. Cunningham, and Louis B. Werner on August 20, 1942. During World War II, which Seaborg spent as a section chief at the University of Chicago Metallurgical Laboratory, the first industrial production of plutonium was undertaken in newly devised uranium reactors, and he had the primary responsibility for isolating plutonium from the reaction products and scaling up its extraction from ultramicroscopic laboratory amounts to a full-scale plant (the Hanford Engineering Works in Washington) by what he called “surely the greatest scale-up factor [10 billion] ever attempted.”

The other new elements discovered by Seaborg were americium (95), curium (96), berkelium (97), californium (98), einsteinium (99), fermium (100), mendelevium (101), nobelium (102), and seaborgium (106). By chance, Seaborg first announced the discovery of elements 95 and 96 in response to a question on a November 11, 1945, Quiz Kids radio program. The prediction of the chemical properties, method of isolation, and placement of these and many heavier elements in the periodic table of the elements was helped greatly by an important organizing principle enunciated by Seaborg in 1944 and known as the actinide concept. This was one of the most significant changes in the periodic table since Russian chemist Dmitry Mendeleyev’s original conception in 1869. Seaborg recognized that the 14 elements heavier than actinium (89) are closely related to it and belong to a separate group in the periodic table, the actinoid elements, analogous to the 14 elements heavier than lanthanum (57), the lanthanoids.

Seaborg returned to Berkeley in 1946, where he was involved in the discovery of berkelium and succeeding elements. He was the first scientist named chairman of the Atomic Energy Commission (1961–71), and the U.S. nuclear weapons and nuclear power industries developed rapidly during his tenure. Beginning in 1959, he was a leader in the movement to improve high-school and college chemistry curricula in the United States and abroad. He was a member of the National Commission on Excellence in Education that produced the 1983 report “A Nation at Risk: The Imperative for Educational Reform.”

A lifelong aficionado of athletics, Seaborg in 1958 helped establish the Athletic Association of Western Universities (now the Pacific-12 Conference). His activities and honors—governmental, academic, and educational—were so multifaceted and extensive that he was cited in the Guinness Book of World Records as having the longest entry in Who’s Who in America.

As an adviser to 10 U.S. presidents, from Franklin D. Roosevelt to George H.W. Bush, Seaborg visited more than 60 countries to promote international scientific cooperation and nuclear arms control treaties. Although he was actively involved in the development of the atomic bomb, he was one of the six signatories of the Franck Report (1945), which urged that the bomb be demonstrated to the Japanese instead of being used against a civilian population. He considered control of nuclear weapons the most crucial problem facing humanity, and he laid the groundwork for the 1968 Treaty on the Non-proliferation of Nuclear Weapons, which he considered “perhaps the most important step in arms limitation since the advent of the nuclear age.”

In 1971 Seaborg returned to the University of California, Berkeley, where he served as university professor, associate director-at-large of the Lawrence Berkeley Laboratory, and chairman of the Lawrence Hall of Science (1984–99). He died from complications of a stroke that he suffered in Boston in August 1998 at a national meeting of the American Chemical Society, the world’s largest organization devoted to a single science, in which he was very active, serving as president in 1976.

Seaborg was the author of The Transuranium Elements (1958), Man-Made Transuranium Elements (1963), Nuclear Milestones: A Collection of Speeches by Glenn T. Seaborg (1972), and A Chemist in the White House: From the Manhattan Project to the End of the Cold War (1998), which chronicles scientific and political issues through his decades of public service, including excerpts from journals and policy-making letters. Shortly after winning the Nobel Prize, Seaborg wrote a number of entries for the 14th edition of the Encyclopædia Britannica, among them the article on plutonium for the 1953 printing.

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