1.
Mushroom cloud
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A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of debris/smoke and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with an explosion. They can be caused by conventional weapons, like vacuum bombs, including the ATBIP. Some volcanic eruptions and impact events can produce natural mushroom clouds, mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The stabilization altitude depends strongly on the profiles of the temperature, dew point, although the term appears to have been coined at the start of the 1950s, mushroom clouds generated by explosions were being described centuries before the atomic era. The Times published a report on 1 October 1937 of a Japanese attack on Shanghai in China which generated a great mushroom of smoke, the 1917 Halifax Explosion also produced one. During World War II, descriptions of mushroom clouds were relatively common, the atomic bomb cloud over Nagasaki, Japan was described in The Times of London of 13 August 1945 as a huge mushroom of smoke and dust. He wrote of the bomb producing a pillar of purple fire, later in 1946, the Operation Crossroads nuclear bomb tests were described as having a cauliflower cloud, but a reporter present also spoke of the mushroom, now the common symbol of the atomic age. Mushrooms have traditionally been associated both with life and death, food and poison, making them a powerful symbolic connection than, say. Mushroom clouds are formed by many sorts of large explosions under earths gravity, without gravity, the explosives by-product gases would remain spherical. Nuclear weapons are usually detonated above the ground, to maximize the effect of their spherically expanding fireball, immediately after the detonation, the fireball begins to rise into the air, acting on the same principle as a hot-air balloon. One way to analyze the motion, once the hot gas has cleared the ground sufficiently, is as a spherical cap bubble, as this gives agreement between the rate of rise and observed diameter. When the detonation altitude is low enough, these afterwinds will draw in dirt, Nuclear detonations produced high above the ground might not create mushroom clouds with a stem. Detonations underwater but near the surface produce a pillar of water, which, in collapsing, forms a cauliflower-like shape, underground detonations at low depth produce a mushroom cloud and a base surge, two different distinct clouds. The amount of radiation vented into the atmosphere decreases rapidly with increasing detonation depth, with surface and near-surface air bursts, the amount of debris lofted into the air decreases rapidly with increasing burst altitude. At burst altitudes of approximately 7 meters/kiloton^0.33, a crater is not formed, the fallout-reducing height, above which the primary radioactive particles consist mainly of the fine fireball condensation, is approximately 55 meters/kiloton^0.4. However, even at these burst altitudes, fallout may be formed by a number of mechanisms, the distribution of radiation in the mushroom cloud varies with yield of the explosion, type of weapon, fusion/fission ratio, burst altitude, terrain type, and weather. In general, lower-yield explosions have about 90% of their radioactivity in the mushroom head, in contrast, megaton-range explosions tend to have most of their radioactivity in the lower third of the mushroom cloud
2.
Nuclear weapons testing
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Nuclear weapons tests are experiments carried out to determine the effectiveness, yield, and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that developed nuclear weapons tested them, the first nuclear device was detonated as a test by the United States at the Trinity site on July 16,1945, with a yield approximately equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of engineer device, codenamed Mike, was tested at the Enewetak atoll in the Marshall Islands on November 1,1952, also by the United States. The largest nuclear weapon ever tested was the Tsar Bomba of the Soviet Union at Novaya Zemlya on October 30,1961, with the largest yield ever seen, the treaty permitted underground nuclear testing. France continued atmospheric testing until 1974, and China continued until 1980, underground tests in the United States continued until 1991, the Soviet Union until 1990, the United Kingdom until 1991, and both China and France until 1996. Non-signatories India and Pakistan last tested nuclear weapons in 1998, North Korea conducted nuclear tests in 2006,2009,2013, and 2016. The most recent confirmed nuclear test occurred in September 2016 in North Korea, Nuclear weapons tests have historically been divided into four categories reflecting the medium or location of the test. Atmospheric testing designates explosions that take place in the atmosphere, Nuclear explosions close enough to the ground to draw dirt and debris into their mushroom cloud can generate large amounts of nuclear fallout due to irradiation of the debris. This definition of atmospheric is used in the Limited Test Ban Treaty, underground testing refers to nuclear tests conducted under the surface of the earth, at varying depths. True underground tests are intended to be contained and emit a negligible amount of fallout. Unfortunately these nuclear tests do occasionally vent to the surface, producing from nearly none to considerable amounts of debris as a consequence. In 1976, the United States and the USSR agreed to limit the maximum yield of underground tests to 150 kt with the Threshold Test Ban Treaty. Underground testing also falls into two categories, tunnel tests in generally horizontal tunnel drifts, and shaft tests in vertically drilled holes. Exoatmospheric testing refers to tests conducted above the atmosphere. The test devices are lifted on rockets, underwater testing results from nuclear devices being detonated underwater, usually moored to a ship or a barge. Tests of this nature have usually been conducted to evaluate the effects of weapons against naval vessels. Another way to nuclear tests are by the number of explosions that constitute the test.1 second. The USSR has exploded up to eight devices in a single salvo test, Pakistans second, almost all lists in the literature are lists of tests, in the lists in Wikipedia, the lists are of explosions
3.
Thermonuclear weapon
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A thermonuclear weapon is a nuclear weapon that uses the energy from a primary nuclear fission reaction to compress and ignite a secondary nuclear fusion reaction. The result is greatly increased power when compared to single-stage fission weapons. It is colloquially referred to as a bomb or an H-bomb because it employs the fusion of isotopes of hydrogen. The first full scale thermonuclear test was carried out by the United States in 1952, similar devices were developed by the Soviet Union, United Kingdom, China, and France. The radiation implosion mechanism is an engine that exploits the temperature difference between the secondary stages hot, surrounding radiation channel and its relatively cool interior. This temperature difference is maintained by a massive heat barrier called the pusher. If made of uranium, as is almost always the case, it can capture neutrons produced by the reaction and undergo fission itself. In many Teller–Ulam weapons, fission of the pusher dominates the explosion, detailed knowledge of fission and fusion weapons is classified to some degree in virtually every industrialized nation. Born secret is rarely invoked for cases of private speculation, in a small number of prior cases, the U. S. government has attempted to censor weapons information in the public press, with limited success. According to the New York Times, physicist Kenneth Ford defied government orders to remove classified information from his new book, Building the H Bomb, the state of public knowledge about the Teller–Ulam design has been mostly shaped from a few specific incidents outlined in a section below. At a bare minimum, this implies a primary section consists of an implosion-type fission bomb. The energy released by the primary compresses the secondary through a process called radiation implosion, at which point it is heated, surrounding the other components is a hohlraum or radiation case, a container that traps the first stage or primarys energy inside temporarily. The outside of this case, which is also normally the outside casing of the bomb, is the only direct visual evidence publicly available of any thermonuclear bomb components configuration. Numerous photographs of various thermonuclear bomb exteriors have been declassified, generally, a research program with the capacity to create a thermonuclear bomb has already mastered the ability to engineer boosted fission. The secondary is usually shown as a column of fusion fuel, around the column is first a pusher-tamper, a heavy layer of uranium-238 or lead that serves to help compress the fusion fuel. Inside this is the fuel itself, usually a form of lithium deuteride. This dry fuel, when bombarded by neutrons, produces tritium, inside the layer of fuel is the spark plug, a hollow column of fissile material that, when compressed, can itself undergo nuclear fission. The tertiary, if one is present, would be set below the secondary, separating the secondary from the primary is the interstage
4.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
5.
Elugelab
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Elugelab was an island, part of the Enewetak atoll in the Marshall Islands. It was increased in size, and then destroyed by the worlds first true hydrogen bomb test on 1 November 1952, prior to being enlarged, and destroyed, the island was described as just another small naked island of the atoll. The fireball created by Ivy Mike had a radius of 2.9 to 3.28 km. This maximum is reached a number of seconds after the detonation, while still relatively close to the ground, the fireball had yet to reach its maximum dimensions and was thus approximately three and one quarter miles wide. The island became dust and ash, pulled upward to form a cloud that rose about twenty-seven miles into the sky. According to Eric Schlosser, all that remained of Elugelab was a crater filled with seawater, more than a mile in diameter. The blast yielded 10.4 megatons of energy,700 times the energy that leveled central Hiroshima. The detonation also collapsed some natural crevices in the reef, some away from the rim of the crater. Full radioecology recovery surveys were documented before and after each test series, krakatoa - a larger island that was destroyed by a much more powerful natural volcanic explosion. Explosion crater Mike Test from PBS
6.
Pacific Ocean
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The Pacific Ocean is the largest and deepest of the Earths oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west, the Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres. Both the center of the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean, the oceans current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means peaceful sea, important human migrations occurred in the Pacific in prehistoric times. Long-distance trade developed all along the coast from Mozambique to Japan, trade, and therefore knowledge, extended to the Indonesian islands but apparently not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality, from 1404 to 1433 Zheng He led expeditions into the Indian Ocean. The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and he named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. Later, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Castilian expedition of world circumnavigation starting in 1519, Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters. The ocean was often called the Sea of Magellan in his honor until the eighteenth century, sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, and Papua New Guinea. In 1542–43 the Portuguese also reached Japan, in 1564, five Spanish ships consisting of 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi and sailed to the Philippines and Mariana Islands. The Manila galleons operated for two and a half centuries linking Manila and Acapulco, in one of the longest trade routes in history, Spanish expeditions also discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, and the Admiralty Islands in the South Pacific. In the 16th and 17th century Spain considered the Pacific Ocean a Mare clausum—a sea closed to other naval powers, as the only known entrance from the Atlantic the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western end of the Pacific Ocean the Dutch threatened the Spanish Philippines, Spain also sent expeditions to the Pacific Northwest reaching Vancouver Island in southern Canada, and Alaska. The French explored and settled Polynesia, and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest, one of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789–1794. It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific. Growing imperialism during the 19th century resulted in the occupation of much of Oceania by other European powers, and later, Japan, in Oceania, France got a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853 respectively. After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro managed to negotiate an incorporation of the island into Chile with native Rapanui in 1888, by occupying Easter Island, Chile joined the imperial nations
7.
Nuclear weapon design
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Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types, in many existing designs, the explosive energy of deployed devices is derived primarily from nuclear fission, not fusion. Pure fission weapons were the first nuclear weapons built and have so far been the type ever used in warfare. Implosion, a mass of either material is surrounded by high explosives that compress the mass. The implosion method can use either uranium or plutonium as fuel, the gun method only uses uranium. Boosted fission weapons improve on the implosion design, the high pressure and temperature environment at the center of an exploding fission weapon compresses and heats a mixture of tritium and deuterium gas. The hydrogen fuses to form helium and free neutrons, boosting can more than double the weapons fission energy release. Staged thermonuclear weapons are essentially a chain of fusion-boosted fission weapons, the secondary stage is imploded by x-ray energy from the first stage, called the primary. This radiation implosion is much more effective than the high-explosive implosion of the primary, consequently, the secondary can be many times more powerful than the primary, without being bigger. The secondary can be designed to maximize fusion energy release, but in most designs fusion is employed only to drive or enhance fission, as it is in the primary. More stages could be added and conceptual designs incorporating up to seven have been produced, pure fusion weapons have not been invented. Such weapons, though, would produce far less radioactive fallout than current designs, pure fission weapons historically have been the first type to be built by a nation state. Most known innovations in nuclear weapon design originated in the United States, although some were developed independently by other states. In early news accounts, pure fission weapons were called atomic bombs or A-bombs, Weapons involving fusion were called hydrogen bombs or H-bombs, also a misnomer since their energy comes mostly from fission. Practitioners favored the terms nuclear and thermonuclear, respectively, the term thermonuclear refers to the high temperatures required to initiate fusion. It omits the equally important factor of radiation pressure, which was considered secret at the time the term became widespread, many nuclear weapon terms similarly obfuscate because of their origin in a classified environment. Nuclear fission separates or splits heavier atoms to form lighter atoms, Nuclear fusion combines together lighter atoms to form heavier atoms. In some ways, fission and fusion are opposite and complementary reactions, to understand how nuclear weapons are designed, it is useful to know the important similarities and differences between fission and fusion
8.
Cryogenics
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In physics, cryogenics is the study of the production and behaviour of materials at very low temperatures. It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume a gas to be cryogenic if it can be liquefied at or below −150 °C. The U. S. National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below −180 °C or −292.00 °F or 93.15 K. A person who studies elements that have been subjected to cold temperatures is called a cryogenicist. Cryogenicists use the Kelvin or Rankine temperature scales present in nature, Cryogenics The branches of physics and engineering that involve the study of very low temperatures, how to produce them, and how materials behave at those temperatures. Cryobiology The branch of biology involving the study of the effects of low temperatures on organisms, cryoconservation of animal genetic resources The conservation of genetic material with the intention of conserving a breed. Cryosurgery The branch of surgery applying very low temperatures to destroy malignant tissue, cryoelectronics The field of research regarding superconductivity at low temperatures. Cryotronics The practical application of cryoelectronics, Cryonics Cryopreserving humans and animals with the intention of future revival. Cryogenics is sometimes used to mean Cryonics in popular culture. The word cryogenics stems from Greek kρύο – cold + genic – having to do with production, Cryogenic fluids with their boiling point in kelvins Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world, Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. These liquids may be stored in Dewar flasks, which are double-walled containers with a vacuum between the walls to reduce heat transfer into the liquid. Typical laboratory Dewar flasks are spherical, made of glass and protected in a metal outer container, Dewar flasks for extremely cold liquids such as liquid helium have another double-walled container filled with liquid nitrogen. Dewar flasks are named after their inventor, James Dewar, the man who first liquefied hydrogen, thermos bottles are smaller vacuum flasks fitted in a protective casing. Cryogenic barcode labels are used to mark dewar flasks containing these liquids, Cryogenic transfer pumps are the pumps used on LNG piers to transfer liquefied natural gas from LNG carriers to LNG storage tanks, as are cryogenic valves. The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear, based on this theory of cryogenic hardening, the commercial cryogenic processing industry was founded in 1966 by Ed Busch. This evolved in the late 1990s into the treatment of other parts, cryogens, such as liquid nitrogen, are further used for specialty chilling and freezing applications. Some chemical reactions, like those used to produce the active ingredients for the popular statin drugs, special cryogenic chemical reactors are used to remove reaction heat and provide a low temperature environment
9.
Deuterium
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Deuterium is one of two stable isotopes of hydrogen. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen isotope, Deuterium has a natural abundance in Earths oceans of about one atom in 6420 of hydrogen. Thus deuterium accounts for approximately 0. 0156% of all the naturally occurring hydrogen in the oceans, the abundance of deuterium changes slightly from one kind of natural water to another. The deuterium isotopes name is formed from the Greek deuteros meaning second, Deuterium was discovered and named in 1931 by Harold Urey. When the neutron was discovered in 1932, this made the structure of deuterium obvious. Soon after deuteriums discovery, Urey and others produced samples of water in which the deuterium content had been highly concentrated. Deuterium is destroyed in the interiors of stars faster than it is produced, other natural processes are thought to produce only an insignificant amount of deuterium. Nearly all deuterium found in nature was produced in the Big Bang 13.8 billion years ago and this is the ratio found in the gas giant planets, such as Jupiter. However, other bodies are found to have different ratios of deuterium to hydrogen-1. This is thought to be as a result of natural isotope separation processes that occur from solar heating of ices in comets, like the water-cycle in Earths weather, such heating processes may enrich deuterium with respect to protium. The analysis of ratios in comets found results very similar to the mean ratio in Earths oceans. This reinforces theories that much of Earths ocean water is of cometary origin, the deuterium/protium ratio of the comet 67P/Churyumov-Gerasimenko, as measured by the Rosetta space probe, is about three times that of earth water. This figure is the highest yet measured in a comet, deuterium/protium ratios thus continue to be an active topic of research in both astronomy and climatology. Deuterium is frequently represented by the chemical symbol D, since it is an isotope of hydrogen with mass number 2, it is also represented by 2H. IUPAC allows both D and 2H, although 2H is preferred, a distinct chemical symbol is used for convenience because of the isotopes common use in various scientific processes. In quantum mechanics the energy levels of electrons in atoms depend on the mass of the system of electron. For hydrogen, this amount is about 1837/1836, or 1.000545, the energies of spectroscopic lines for deuterium and light-hydrogen therefore differ by the ratios of these two numbers, which is 1.000272. The wavelengths of all deuterium spectroscopic lines are shorter than the lines of light hydrogen
10.
Nuclear fission
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In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts. The fission process often produces free neutrons and gamma photons, Frisch named the process by analogy with biological fission of living cells. It is a reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments. In order for fission to produce energy, the binding energy of the resulting elements must be less negative than that of the starting element. Fission is a form of nuclear transmutation because the fragments are not the same element as the original atom. The two nuclei produced are most often of comparable but slightly different sizes, typically with a ratio of products of about 3 to 2. Most fissions are binary fissions, but occasionally, three positively charged fragments are produced, in a ternary fission, the smallest of these fragments in ternary processes ranges in size from a proton to an argon nucleus. Nuclear fission produces energy for power and drives the explosion of nuclear weapons. Both uses are possible because certain substances called nuclear fuels undergo fission when struck by fission neutrons and this makes possible a self-sustaining nuclear chain reaction that releases energy at a controlled rate in a nuclear reactor or at a very rapid uncontrolled rate in a nuclear weapon. Nuclear fission can occur without neutron bombardment as a type of radioactive decay and this type of fission is rare except in a few heavy isotopes. In engineered nuclear devices, essentially all nuclear fission occurs as a nuclear reaction — a bombardment-driven process that results from the collision of two subatomic particles, in nuclear reactions, a subatomic particle collides with an atomic nucleus and causes changes to it. Nuclear reactions are driven by the mechanics of bombardment, not by the relatively constant exponential decay. Many types of reactions are currently known. Nuclear fission differs importantly from other types of reactions, in that it can be amplified. In such a reaction, free neutrons released by each fission event can trigger yet more events, the chemical element isotopes that can sustain a fission chain reaction are called nuclear fuels, and are said to be fissile. The most common nuclear fuels are 235U and 239Pu and these fuels break apart into a bimodal range of chemical elements with atomic masses centering near 95 and 135 u. Most nuclear fuels undergo spontaneous fission only very slowly, decaying instead mainly via an alpha-beta decay chain over periods of millennia to eons. In a nuclear reactor or nuclear weapon, the majority of fission events are induced by bombardment with another particle, a neutron
11.
Enrico Fermi
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Enrico Fermi was an Italian physicist, who created the worlds first nuclear reactor, the Chicago Pile-1. He has been called the architect of the age and the architect of the atomic bomb. He was one of the few physicists to excel both theoretically and experimentally and he made significant contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics. Fermis first major contribution was to statistical mechanics, today, particles that obey the exclusion principle are called fermions. Later Pauli postulated the existence of an invisible particle emitted along with an electron during beta decay. Fermi took up this idea, developing a model that incorporated the postulated particle and his theory, later referred to as Fermis interaction and still later as weak interaction, described one of the four fundamental forces of nature. Fermi left Italy in 1938 to escape new Italian Racial Laws that affected his Jewish wife Laura Capon and he emigrated to the United States where he worked on the Manhattan Project during World War II. Fermi led the team designed and built Chicago Pile-1, which went critical on 2 December 1942. He was on hand when the X-10 Graphite Reactor at Oak Ridge, Tennessee, went critical in 1943, at Los Alamos he headed F Division, part of which worked on Edward Tellers thermonuclear Super bomb. He was present at the Trinity test on 16 July 1945, after the war, Fermi served under J. Robert Oppenheimer on the General Advisory Committee, which advised the Atomic Energy Commission on nuclear matters and policy. Following the detonation of the first Soviet fission bomb in August 1949 and he was among the scientists who testified on Oppenheimers behalf at the 1954 hearing that resulted in the denial of the latters security clearance. Enrico Fermi was born in Rome, Italy, on 29 September 1901 and he was the third child of Alberto Fermi, a division head in the Ministry of Railways, and Ida de Gattis, an elementary school teacher. His only sister, Maria, was two years older than he was, and his brother Giulio was a year older, after the two boys were sent to a rural community to be wet nursed, Enrico rejoined his family in Rome when he was two and a half. Although he was baptised a Roman Catholic in accordance with his grandparents wishes, his family was not particularly religious, as a young boy he shared the same interests as his brother Giulio, building electric motors and playing with electrical and mechanical toys. Giulio died during the administration of an anesthetic for an operation on a throat abscess in 1915, one of Fermis first sources for his study of physics was a book he found at the local market at Campo de Fiori in Rome. Published in 1840, the 900-page Elementorum physicae mathematicae, was written in Latin by Jesuit Father Andrea Caraffa and it covered mathematics, classical mechanics, astronomy, optics, and acoustics, insofar as these disciplines were understood when the book was written. Fermis interest in physics was encouraged by his fathers colleague Adolfo Amidei, who gave him several books on physics and mathematics. Fermi graduated from school in July 1918 and, at Amideis urging
12.
Plutonium
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Plutonium is a transuranic radioactive chemical element with symbol Pu and atomic number 94. It is a metal of silvery-gray appearance that tarnishes when exposed to air. The element normally exhibits six allotropes and four oxidation states and it reacts with carbon, halogens, nitrogen, silicon and hydrogen. When exposed to moist air, it forms oxides and hydrides that can expand the sample up to 70% in volume and it is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous. Plutonium was first produced and isolated on December 14,1940 by Dr. Glenn T. Seaborg, Joseph W. Kennedy, Edwin M. McMillan, wahl by deuteron bombardment of uranium-238 in the 60-inch cyclotron at the University of California, Berkeley. They first synthesized neptunium-238 which subsequently beta-decayed to form a new element with atomic number 94. Uranium had been named after the planet Uranus and neptunium after the planet Neptune, and so element 94 was named after Pluto, wartime secrecy prevented them from announcing the discovery until 1948. Plutonium is the heaviest element to occur in nature as trace quantities arising similarly from the capture of natural uranium-238. Both plutonium-239 and plutonium-241 are fissile, meaning that they can sustain a chain reaction, leading to applications in nuclear weapons. Plutonium-240 exhibits a high rate of fission, raising the neutron flux of any sample containing it. The presence of plutonium-240 limits a plutonium samples usability for weapons or its quality as reactor fuel, plutonium-238 has a half-life of 88 years and emits alpha particles. It is a source in radioisotope thermoelectric generators, which are used to power some spacecraft. Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors, producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II that developed the first atomic bombs. The Fat Man bombs used in the Trinity nuclear test in July 1945, Human radiation experiments studying plutonium were conducted without informed consent, and several criticality accidents, some lethal, occurred after the war. Disposal of plutonium waste from power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation. Other sources of plutonium in the environment are fallout from numerous above-ground nuclear tests, Plutonium, like most metals, has a bright silvery appearance at first, much like nickel, but it oxidizes very quickly to a dull gray, although yellow and olive green are also reported. At room temperature plutonium is in its α form and this, the most common structural form of the element, is about as hard and brittle as gray cast iron unless it is alloyed with other metals to make it soft and ductile. Unlike most metals, it is not a conductor of heat or electricity
