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Calutron Diffusion Pumps
A calutron is a mass spectrometer originally designed and used for separating the isotopes of uranium. It was developed by Ernest Lawrence during the Manhattan Project and was based on his earlier invention, the cyclotron. Its name was derived from California University Cyclotron, in tribute to Lawrence's institution, the University of California, where it was invented. Calutrons were used in the industrial-scale Y-12 uranium enrichment plant at the Clinton Engineer Works in Oak Ridge, Tennessee. The enriched uranium produced was used in the Little Boy atomic bomb that was detonated over Hiroshima on 6 August 1945. The calutron is a type of sector mass spectrometer, an instrument in which a sample is ionized and then accelerated by electric fields and deflected by magnetic fields. The ions ultimately collide with a plate and produce a measurable electric current. Since the ions of the different isotopes have the same electric charge but different masses, the heavier isotopes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Calutron Tank
Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , which is the West Semitic word for " ox". Letters that arose from alpha include the Latin letter A and the Cyrillic letter А. Uses Greek In Ancient Greek, alpha was pronounced and could be either phonemically long ( ː or short ( . Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: Ᾱᾱ, Ᾰᾰ. * ὥρα = ὥρᾱ ''hōrā'' "a time" * γλῶσσα = γλῶσσᾰ ''glôssa'' "tongue" In Modern Greek, vowel length has been lost, and all instances of alpha simply represent the open front unrounded vowel . In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (), and either of two breathing marks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionized
Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule is called an ion. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected. Uses Everyday examples of gas ionization are such as within a fluorescent lamp or other electrical discharge lamps. It is also used in radiation detectors such as the Geiger-Müller counter or the ionization chamber. The ionizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium-235
Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nature as a primordial nuclide. Uranium-235 has a half-life of 703.8 million years. It was discovered in 1935 by Arthur Jeffrey Dempster. Its fission cross section for slow thermal neutrons is about 584.3±1 barns. For fast neutrons it is on the order of 1 barn. Most but not all neutron absorptions result in fission; a minority result in neutron capture forming uranium-236. Natural decay chain :\begin \ce \begin \ce \\ \ce \end \ce \\ \ce \begin \ce \\ \ce \end \ce \end Fission properties The fission of one atom of uranium-235 releases () inside the reactor. That corresponds to 19.54 TJ/ mol, or 83.14 TJ/kg. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Drop Model
In nuclear physics, the semi-empirical mass formula (SEMF) (sometimes also called the Weizsäcker formula, Bethe–Weizsäcker formula, or Bethe–Weizsäcker mass formula to distinguish it from the Bethe–Weizsäcker process) is used to approximate the mass and various other properties of an atomic nucleus from its number of protons and neutrons. As the name suggests, it is based partly on theory and partly on empirical measurements. The formula represents the liquid-drop model proposed by George Gamow, which can account for most of the terms in the formula and gives rough estimates for the values of the coefficients. It was first formulated in 1935 by German physicist Carl Friedrich von Weizsäcker, and although refinements have been made to the coefficients over the years, the structure of the formula remains the same today. The formula gives a good approximation for atomic masses and thereby other effects. However, it fails to explain the existence of lines of greater binding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niels Bohr
Niels Henrik David Bohr (; 7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research. Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another. Although the Bohr model has been supplanted by other models, its underlying principles remain valid. He conceived the principle of complementarity: that items could be separately analysed in terms of contradictory properties, like behaving as a wave or a stream of particles. The notion of complementarity dominated Bohr's thinking in both science and philosophy. Bohr founded the Institute of Theoretical Physics at the University of Cope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Frisch
Otto Robert Frisch FRS (1 October 1904 – 22 September 1979) was an Austrian-born British physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission (coining the term) and first experimentally detected the fission by-products. Later, with his collaborator Rudolf Peierls he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940. Early life Frisch was born in Vienna in 1904 to a Jewish family, the son of Justinian Frisch, a painter, and Auguste Meitner Frisch, a concert pianist. He himself was talented at both but also shared his aunt Lise Meitner's love of physics and commenced a period of study at the University of Vienna, graduating in 1926 with some work on the effect of the newly discovered electron on salts. Nuclear physics After some years working in relatively obscure laboratories in Germany, Frisch obtained a position in Hamburg under the Nobel Prize-winning scientist Otto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lise Meitner
Elise Meitner ( , ; 7 November 1878 – 27 October 1968) was an Austrian-Swedish physicist who was one of those responsible for the discovery of the element protactinium and nuclear fission. While working at the Kaiser Wilhelm Institute on radioactivity, she discovered the radioactive isotope protactinium-231 in 1917. In 1938, Meitner and her nephew, the physicist Otto Robert Frisch, discovered nuclear fission. She was praised by Albert Einstein as the "German Marie Curie". Completing her doctoral research in 1905, Meitner became the second woman from the University of Vienna to earn a doctorate in physics. She spent most of her scientific career in Berlin, Germany, where she was a physics professor and a department head at the Kaiser Wilhelm Institute; she was the first woman to become a full professor of physics in Germany. She lost these positions in the 1930s because of the anti-Jewish Nuremberg Laws of Nazi Germany, and in 1938 she fled to Sweden, where she lived for many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fritz Strassmann
Friedrich Wilhelm Strassmann (; 22 February 1902 – 22 April 1980) was a German chemist who, with Otto Hahn in December 1938, identified the element barium as a product of the bombardment of uranium with neutrons. Their observation was the key piece of evidence necessary to identify the previously unknown phenomenon of nuclear fission, as was subsequently recognized and published by Lise Meitner and Otto Frisch. Personal life and education Strassman was born in Boppard, Germany, to Richard Strassman and Julie Strassmann (née Bernsmann). He was the youngest of nine children. Growing up in Düsseldorf, he developed an interest in chemistry at a young age and conducted chemistry experiments in his parents' home. His family was of modest means, and his father died at a young age, worsening the family's financial situation. Financial considerations limited Strassmann's initial choices of where to pursue his higher education and what subjects they should be. Strassmann began his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Hahn
Otto Hahn (; 8 March 1879 – 28 July 1968) was a German chemist who was a pioneer in the fields of radioactivity and radiochemistry. He is referred to as the father of nuclear chemistry and father of nuclear fission. Hahn and Lise Meitner discovered radioactive isotopes of radium, thorium, protactinium and uranium. He also discovered the phenomena of atomic recoil and nuclear isomerism, and pioneered rubidium–strontium dating. In 1938, Hahn, Lise Meitner and Fritz Strassmann discovered nuclear fission, for which Hahn received the 1944 Nobel Prize for Chemistry. Nuclear fission was the basis for nuclear reactors and nuclear weapons. A graduate of the University of Marburg, Hahn studied under Sir William Ramsay at University College London and at McGill University in Montreal under Ernest Rutherford, where he discovered several new radioactive isotopes. He returned to Germany in 1906; Emil Fischer placed a former woodworking shop in the basement of the Chemical Institute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discovery Of Nuclear Fission
Nuclear fission was discovered in December 1938 by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei and often other particles. The fission process often produces gamma rays and releases a very large amount of energy, even by the energetic standards of radioactive decay. Scientists already knew about alpha decay and beta decay, but fission assumed great importance because the discovery that a nuclear chain reaction was possible led to the development of nuclear power and nuclear weapons. Hahn was awarded the 1944 Nobel Prize in Chemistry for the discovery of nuclear fission. Hahn and Strassmann at the Max Planck Institute for Chemistry, Kaiser Wilhelm Institute for Chemistry in Berlin bombarded uranium with slow neutrons and discovered that barium had been produced. Hahn suggested a bursting of the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaseous Diffusion
Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride (UF6) through semipermeable membranes. This produces a slight separation between the molecules containing uranium-235 (235U) and uranium-238 (238U). By use of a large cascade of many stages, high separations can be achieved. It was the first process to be developed that was capable of producing enriched uranium in industrially useful quantities, but is nowadays considered obsolete, having been superseded by the more-efficient gas centrifuge process. Gaseous diffusion was devised by Francis Simon and Nicholas Kurti at the Clarendon Laboratory in 1940, tasked by the MAUD Committee with finding a method for separating uranium-235 from uranium-238 in order to produce a bomb for the British Tube Alloys project. The prototype gaseous diffusion equipment itself was manufactured by Metropolitan-Vickers (MetroVick) at Trafford Park, Manchester, at a cost of £150,000 for four units, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary particles, theoretically with the same amount of matter, have nonetheless different masses. Mass in modern physics has multiple definitions which are conceptually distinct, but physically equivalent. Mass can be experimentally defined as a measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied. The object's mass also determines the strength of its gravitational attraction to other bodies. The SI base unit of mass is the kilogram (kg). In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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