1.
Mass spectrometry
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Mass spectrometry is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio. In simpler terms, a mass spectrum measures the masses within a sample, mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio, in a typical MS procedure, a sample, which may be solid, liquid, or gas, is ionized, for example by bombarding it with electrons. This may cause some of the molecules to break into charged fragments. The ions are detected by a capable of detecting charged particles. Results are displayed as spectra of the abundance of detected ions as a function of the mass-to-charge ratio. The atoms or molecules in the sample can be identified by correlating known masses to the masses or through a characteristic fragmentation pattern. Goldstein called these positively charged anode rays Kanalstrahlen, the translation of this term into English is canal rays. Wien found that the charge-to-mass ratio depended on the nature of the gas in the discharge tube, thomson later improved on the work of Wien by reducing the pressure to create the mass spectrograph. The word spectrograph had become part of the international scientific vocabulary by 1884, a mass spectroscope is similar to a mass spectrograph except that the beam of ions is directed onto a phosphor screen. A mass spectroscope configuration was used in early instruments when it was desired that the effects of adjustments be quickly observed, once the instrument was properly adjusted, a photographic plate was inserted and exposed. The term mass spectroscope continued to be used though the direct illumination of a phosphor screen was replaced by indirect measurements with an oscilloscope. The use of the mass spectroscopy is now discouraged due to the possibility of confusion with light spectroscopy. Mass spectrometry is often abbreviated as mass-spec or simply as MS, modern techniques of mass spectrometry were devised by Arthur Jeffrey Dempster and F. W. Aston in 1918 and 1919 respectively. Sector mass spectrometers known as calutrons were used for separating the isotopes of uranium developed by Ernest O. Lawrence during the Manhattan Project, calutron mass spectrometers were used for uranium enrichment at the Oak Ridge, Tennessee Y-12 plant established during World War II. In 1989, half of the Nobel Prize in Physics was awarded to Hans Dehmelt, a mass spectrometer consists of three components, an ion source, a mass analyzer, and a detector. The ionizer converts a portion of the sample into ions, there is a wide variety of ionization techniques, depending on the phase of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample, which are then targeted through the mass analyzer, the differences in masses of the fragments allows the mass analyzer to sort the ions by their mass-to-charge ratio
2.
Particle accelerator
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A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to nearly light speed and to contain them in well-defined beams. Large accelerators are used in physics as colliders, or as synchrotron light sources for the study of condensed matter physics. There are currently more than 30,000 accelerators in operation around the world, there are two basic classes of accelerators, electrostatic and electrodynamic accelerators. Electrostatic accelerators use electric fields to accelerate particles. The most common types are the Cockcroft–Walton generator and the Van de Graaff generator, a small-scale example of this class is the cathode ray tube in an ordinary old television set. The achievable kinetic energy for particles in these devices is determined by the accelerating voltage, electrodynamic or electromagnetic accelerators, on the other hand, use changing electromagnetic fields to accelerate particles. Since in these types the particles can pass through the accelerating field multiple times. This class, which was first developed in the 1920s, is the basis for most modern large-scale accelerators, because colliders can give evidence of the structure of the subatomic world, accelerators were commonly referred to as atom smashers in the 20th century. Despite the fact that most accelerators actually propel subatomic particles, the term persists in popular usage when referring to particle accelerators in general. Beams of high-energy particles are useful for both fundamental and applied research in the sciences, and also in many technical and industrial fields unrelated to fundamental research and it has been estimated that there are approximately 30,000 accelerators worldwide. The bar graph shows the breakdown of the number of industrial accelerators according to their applications, for the most basic inquiries into the dynamics and structure of matter, space, and time, physicists seek the simplest kinds of interactions at the highest possible energies. These typically entail particle energies of many GeV, and the interactions of the simplest kinds of particles, leptons and quarks for the matter, the largest and highest energy particle accelerator used for elementary particle physics is the Large Hadron Collider at CERN, operating since 2009. These investigations often involve collisions of heavy nuclei – of atoms like iron or gold – at energies of several GeV per nucleon, the largest such particle accelerator is the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. An example of type of machine is LANSCE at Los Alamos. A large number of light sources exist worldwide. The ESRF in Grenoble, France has been used to extract detailed 3-dimensional images of trapped in amber. Thus there is a demand for electron accelerators of moderate energy. Everyday examples of particle accelerators are cathode ray tubes found in television sets and these low-energy accelerators use a single pair of electrodes with a DC voltage of a few thousand volts between them
3.
Ion source
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An ion source is a device that creates atomic and molecular ions. Ion sources are used to form ions for mass spectrometers, optical emission spectrometers, particle accelerators, ion implanters, Electron ionization is widely used in mass spectrometry, particularly for organic molecules. The electrons may be created by an arc discharge between a cathode and an anode, an electron beam ion source is used in atomic physics to produce highly charged ions by bombarding atoms with a powerful electron beam. Its principle of operation is shared by the electron beam ion trap, Electron capture ionization is the ionization of a gas phase atom or molecule by attachment of an electron to create an ion of the form A−•. The reaction is A + e − → M A − where the M over the arrow denotes that to conserve energy, Electron capture can be used in conjunction with chemical ionization. An electron capture detector is used in gas chromatography systems. Chemical ionization is a lower energy process than electron ionization because it involves ion/molecule reactions rather than electron removal, the lower energy yields less fragmentation, and usually a simpler spectrum. A typical CI spectrum has an easily identifiable molecular ion, in a CI experiment, ions are produced through the collision of the analyte with ions of a reagent gas in the ion source. Some common reagent gases include, methane, ammonia, and isobutane, inside the ion source, the reagent gas is present in large excess compared to the analyte. Electrons entering the source will preferentially ionize the reagent gas, the resultant collisions with other reagent gas molecules will create an ionization plasma. Positive and negative ions of the analyte are formed by reactions with this plasma. For example, protonation occurs by CH4 + e − ⟶ CH4 + +2 e −, charge-exchange ionization is a gas phase reaction between an ion and an atom or molecule in which the charge of the ion is transferred to the neutral species. A + + B ⟶ A + B + Chemi-ionization is the formation of an ion through the reaction of a gas atom or molecule with an atom or molecule in an excited state. Associative ionization is a gas phase reaction in which two atoms or molecules interact to form a single product ion, one or both of the interacting species may have excess internal energy. For example, A ∗ + B ⟶ AB + ∙ + e − where species A with excess internal energy interacts with B to form the ion AB+, Penning ionization is a form of chemi-ionization involving reactions between neutral atoms or molecules. The process is named after the Dutch physicist Frans Michel Penning who first reported it in 1927, Penning ionization involves a reaction between a gas-phase excited-state atom or molecule G* and a target molecule M resulting in the formation of a radical molecular cation M+. In a radioactive ion source, a piece of radioactive material. This is used in smoke detectors and ion mobility spectrometers
4.
Van de Graaff generator
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It produces very high voltage direct current electricity at low current levels. It was invented by American physicist Robert J. Van de Graaff during 1929, the potential difference achieved by modern Van de Graaff generators can be as much as 5 megavolts. A tabletop version can produce on the order of 100,000 volts, small Van de Graaff machines are produced for entertainment, and for physics education to teach electrostatics, larger ones are displayed in some science museums. The Van de Graaff generator was developed as an accelerator for physics research. It was the most powerful type of accelerator of the 1930s until the cyclotron was developed, Van de Graaff generators are still used as accelerators to generate energetic particle and x-ray beams for nuclear medicine research. In order to double the voltage, two generators are used together, one generating positive and the other negative potential, this is termed a tandem Van de Graaff accelerator. For example, the Brookhaven National Laboratory Tandem Van de Graaff achieves about 30 million volts of potential difference, the voltage produced by an open-air Van de Graaff machine is limited by arcing and corona discharge to about 5 megavolts. Most modern industrial machines are enclosed in a tank of insulating gas. A simple Van de Graaff generator consists of a belt of rubber moving over two rollers of differing material, one of which is surrounded by a metal sphere. Two electrodes, and, in the form of comb-shaped rows of sharp points, are positioned near the bottom of the lower roller and inside the sphere. Comb is connected to the sphere, and comb to ground, the method of charging is based on the triboelectric effect, such that simple contact of dissimilar materials causes the transfer of some electrons from one material to the other. For example, the rubber of the belt will become negatively charged while the glass of the upper roller will become positively charged. The belt carries away negative charge on its surface while the upper roller accumulates positive charge. Next, the electric field surrounding the positive upper roller induces a very high electric field near the points of the nearby comb. At the points, the field becomes strong enough to ionize air molecules, at the comb they are neutralized by electrons that were on the comb, thus leaving the comb and the attached outer shell with fewer net electrons. Electrostatic induction by this method continues, building up large amounts of charge on the shell. In the example, the roller is metal, which picks negative charge off the inner surface of the belt. The lower comb develops an electric field at its points that also becomes large enough to ionize air molecules
5.
Luis Walter Alvarez
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Luis Walter Alvarez was an American experimental physicist, inventor, and professor who was awarded the Nobel Prize in Physics in 1968. The American Journal of Physics commented, Luis Alvarez was one of the most brilliant, after receiving his PhD from the University of Chicago in 1936, Alvarez went to work for Ernest Lawrence at the Radiation Laboratory at the University of California in Berkeley. Alvarez devised a set of experiments to observe K-electron capture in radioactive nuclei, predicted by the decay theory. He produced tritium using the cyclotron and measured its lifetime, in collaboration with Felix Bloch, he measured the magnetic moment of the neutron. Enemy submarines would wait until the signal was getting strong and then submerge. The radar system for which Alvarez is best known and which has played a role in aviation. Alvarez spent a few months at the University of Chicago working on nuclear reactors for Enrico Fermi before coming to Los Alamos to work for Robert Oppenheimer on the Manhattan project, Alvarez worked on the design of explosive lenses, and the development of exploding-bridgewire detonators. As a member of Project Alberta, he observed the Trinity nuclear test from a B-29 Superfortress and this work resulted in his being awarded the Nobel Prize in 1968. He was involved in a project to x-ray the Egyptian pyramids to search for unknown chambers, with his son, geologist Walter Alvarez, he developed the Alvarez hypothesis which proposes that the extinction event that wiped out the dinosaurs was the result of an asteroid impact. Alvarez was a member of the JASON Defense Advisory Group, the Bohemian Club, Luis Walter Alvarez was born in San Francisco on June 13,1911, the second child and oldest son of Walter C. He had a sister, Gladys, a younger brother, Bob. His aunt, Mabel Alvarez, was a California artist specializing in oil painting and he attended Madison School in San Francisco from 1918 to 1924, and then San Francisco Polytechnic High School. In 1926, his became an researcher at the Mayo Clinic, and the family moved to Rochester, Minnesota. As an undergraduate, he belonged to the Phi Gamma Delta fraternity, as a postgraduate he moved to Gamma Alpha. In 1932, as a student at Chicago, he discovered physics there and had the rare opportunity to use the equipment of legendary physicist Albert A. Michelson. Observing more incoming radiation from the west, Alvarez concluded that primary cosmic rays were positively charged, compton submitted the resulting paper to the Physical Review, with Alvarezs name at the top. Alvarezs sister, Gladys, worked for Ernest Lawrence as a part-time secretary, Lawrence then invited Alvarez to tour the Century of Progress exhibition in Chicago with him. After he completed his exams in 1936, Alvarez, now engaged to be married to Geraldine Smithwick
6.
Cyclotron
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A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1934 in which charged particles accelerate outwards from the centre along a spiral path. The particles are held to a spiral trajectory by a magnetic field. Lawrence was awarded the 1939 Nobel prize in physics for this invention, the largest single-magnet cyclotron was the 4.67 m synchrocyclotron built between 1940 and 1946 by Lawrence at the University of California at Berkeley, which could accelerate protons to 730 MeV. The largest cyclotron is the 17.1 m multimagnet TRIUMF accelerator at the University of British Columbia in Vancouver, there are over 1200 cyclotrons used in nuclear medicine worldwide for the production of radionuclides. The cyclotron was conceived in Germany in the 1920s, at Aachen University in 1926, the cyclotron was proposed by a co-student of Rolf Widerøe, who rejected the idea as too complicated to construct. In 1927, Max Steenbeck developed the concept of the cyclotron at Siemens, the first cyclotron patent was filed by Hungarian physicist Leo Szilard in 1929, while working at Humboldt University of Berlin. The cyclotron was developed and patented by Ernest Lawrence of the University of California, Berkeley. Lawrence went on to make a working cyclotron using large electromagnets from Poulsen arc radio transmitters provided by the Federal Telegraph Company. A graduate student, M. Stanley Livingston, did much of the work of translating the idea into working hardware, Lawrence read an article about the concept of a drift tube linac by Rolf Widerøe, who had also been working along similar lines with the betatron concept. He also developed a 467 cm synchrocyclotron, the first European cyclotron was constructed in Leningrad in the physics department of the Radium Institute, headed by Vitaly Khlopin. This Leningrad instrument was first proposed in 1932 by George Gamow and Lev Mysovskii and was installed, in Nazi Germany a cyclotron was built in Heidelberg under supervision of Walther Bothe and Wolfgang Gentner, with support from the Heereswaffenamt, and became operative in 1943. A cyclotron accelerates a charged particle beam using a high alternating voltage which is applied between two hollow D-shaped sheet metal electrodes called dees inside a vacuum chamber. The dees are placed face to face with a gap between them, creating a cylindrical space within them for the particles to move. The particles are injected into the center of this space, the dees are located between the poles of a large electromagnet which applies a static magnetic field B perpendicular to the electrode plane. The magnetic field causes the path to bend in a circle due to the Lorentz force perpendicular to their direction of motion. If the particles speed were constant, they would travel in a path within the dees under the influence of the magnetic field. However a radio frequency alternating voltage of several thousand volts is applied between the dees, the frequency is set so that the particles make one circuit during a single cycle of the voltage. Each time after the pass to the other dee electrode the polarity of the RF voltage reverses
7.
Archaeology
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Archaeology, or archeology, is the study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, Archaeology can be considered both a social science and a branch of the humanities. In North America, archaeology is considered a sub-field of anthropology, archaeologists study human prehistory and history, from the development of the first stone tools at Lomekwi in East Africa 3.3 million years ago up until recent decades. Archaeology as a field is distinct from the discipline of palaeontology, Archaeology is particularly important for learning about prehistoric societies, for whom there may be no written records to study. Prehistory includes over 99% of the human past, from the Paleolithic until the advent of literacy in societies across the world, Archaeology has various goals, which range from understanding culture history to reconstructing past lifeways to documenting and explaining changes in human societies through time. The discipline involves surveying, excavation and eventually analysis of data collected to learn more about the past, in broad scope, archaeology relies on cross-disciplinary research. Archaeology developed out of antiquarianism in Europe during the 19th century, Archaeology has been used by nation-states to create particular visions of the past. Nonetheless, today, archaeologists face many problems, such as dealing with pseudoarchaeology, the looting of artifacts, a lack of public interest, the science of archaeology grew out of the older multi-disciplinary study known as antiquarianism. Antiquarians studied history with attention to ancient artifacts and manuscripts. Tentative steps towards the systematization of archaeology as a science took place during the Enlightenment era in Europe in the 17th and 18th centuries, in Europe, philosophical interest in the remains of Greco-Roman civilization and the rediscovery of classical culture began in the late Middle Age. Antiquarians, including John Leland and William Camden, conducted surveys of the English countryside, one of the first sites to undergo archaeological excavation was Stonehenge and other megalithic monuments in England. John Aubrey was a pioneer archaeologist who recorded numerous megalithic and other monuments in southern England. He was also ahead of his time in the analysis of his findings and he attempted to chart the chronological stylistic evolution of handwriting, medieval architecture, costume, and shield-shapes. Excavations were also carried out in the ancient towns of Pompeii and Herculaneum and these excavations began in 1748 in Pompeii, while in Herculaneum they began in 1738. The discovery of entire towns, complete with utensils and even human shapes, however, prior to the development of modern techniques, excavations tended to be haphazard, the importance of concepts such as stratification and context were overlooked. The father of archaeological excavation was William Cunnington and he undertook excavations in Wiltshire from around 1798, funded by Sir Richard Colt Hoare. Cunnington made meticulous recordings of neolithic and Bronze Age barrows, one of the major achievements of 19th century archaeology was the development of stratigraphy. The idea of overlapping strata tracing back to successive periods was borrowed from the new geological and paleontological work of scholars like William Smith, James Hutton, the application of stratigraphy to archaeology first took place with the excavations of prehistorical and Bronze Age sites
8.
Radiocarbon dating
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Radiocarbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was developed by Willard Libby in the late 1940s, Libby received the Nobel Prize for his work in 1960. The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen. The resulting radiocarbon combines with oxygen to form radioactive carbon dioxide. When the animal or plant dies, it stops exchanging carbon with its environment, and from that point onwards the amount of 14C it contains begins to decrease as the 14C undergoes radioactive decay. Measuring the amount of 14C in a sample from a plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died. The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained. Research has been ongoing since the 1960s to determine what the proportion of 14C in the atmosphere has been over the past fifty thousand years. The resulting data, in the form of a curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the samples calendar age. Other corrections must be made to account for the proportion of 14C in different types of organisms, additional complications come from the burning of fossil fuels such as coal and oil, and from the above-ground nuclear tests done in the 1950s and 1960s. Conversely, nuclear testing increased the amount of 14C in the atmosphere, measurement of radiocarbon was originally done by beta-counting devices, which counted the amount of beta radiation emitted by decaying 14C atoms in a sample. The development of dating has had a profound impact on archaeology. In addition to permitting more accurate dating within archaeological sites than previous methods, histories of archaeology often refer to its impact as the radiocarbon revolution. Radiocarbon dating has allowed key transitions in prehistory to be dated, such as the end of the last ice age, and they synthesized 14C using the laboratorys cyclotron accelerator and soon discovered that the atoms half-life was far longer than had been previously thought. This was followed by a prediction by Serge A. Korff, then employed at the Franklin Institute in Philadelphia and it had previously been thought that 14C would be more likely to be created by deuterons interacting with 13C. At some time during World War II, Willard Libby, who was then at Berkeley, learned of Korffs research, in 1945, Libby moved to the University of Chicago where he began his work on radiocarbon dating. He published a paper in 1946 in which he proposed that the carbon in living matter might include 14C as well as non-radioactive carbon, by contrast, methane created from petroleum showed no radiocarbon activity because of its age. The results were summarized in a paper in Science in 1947, Libby and James Arnold proceeded to test the radiocarbon dating theory by analyzing samples with known ages
9.
IUPAC books
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The Compendium of Chemical Terminology is a book published by the International Union of Pure and Applied Chemistry containing internationally accepted definitions for terms in chemistry. Work on the first edition was initiated by Victor Gold, hence its informal name, the first edition was published in 1987 and the second edition, edited by A. D. McNaught and A. Wilkinson, was published in 1997. A slightly expanded version of the Gold Book is also freely searchable online, translations have also been published in French, Spanish and Polish
10.
University of Oxford
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The University of Oxford is a collegiate research university located in Oxford, England. It grew rapidly from 1167 when Henry II banned English students from attending the University of Paris, after disputes between students and Oxford townsfolk in 1209, some academics fled north-east to Cambridge where they established what became the University of Cambridge. The two ancient universities are frequently referred to as Oxbridge. The university is made up of a variety of institutions, including 38 constituent colleges, All the colleges are self-governing institutions within the university, each controlling its own membership and with its own internal structure and activities. Being a city university, it not have a main campus, instead, its buildings. Oxford is the home of the Rhodes Scholarship, one of the worlds oldest and most prestigious scholarships, the university operates the worlds oldest university museum, as well as the largest university press in the world and the largest academic library system in Britain. Oxford has educated many notable alumni, including 28 Nobel laureates,27 Prime Ministers of the United Kingdom, the University of Oxford has no known foundation date. Teaching at Oxford existed in form as early as 1096. It grew quickly in 1167 when English students returned from the University of Paris, the historian Gerald of Wales lectured to such scholars in 1188 and the first known foreign scholar, Emo of Friesland, arrived in 1190. The head of the university had the title of chancellor from at least 1201, the university was granted a royal charter in 1248 during the reign of King Henry III. After disputes between students and Oxford townsfolk in 1209, some academics fled from the violence to Cambridge, the students associated together on the basis of geographical origins, into two nations, representing the North and the South. In later centuries, geographical origins continued to many students affiliations when membership of a college or hall became customary in Oxford. At about the time, private benefactors established colleges as self-contained scholarly communities. Among the earliest such founders were William of Durham, who in 1249 endowed University College, thereafter, an increasing number of students lived in colleges rather than in halls and religious houses. In 1333–34, an attempt by some dissatisfied Oxford scholars to found a new university at Stamford, Lincolnshire was blocked by the universities of Oxford and Cambridge petitioning King Edward III. Thereafter, until the 1820s, no new universities were allowed to be founded in England, even in London, thus, Oxford and Cambridge had a duopoly, the new learning of the Renaissance greatly influenced Oxford from the late 15th century onwards. Among university scholars of the period were William Grocyn, who contributed to the revival of Greek language studies, and John Colet, the noted biblical scholar. With the English Reformation and the breaking of communion with the Roman Catholic Church, recusant scholars from Oxford fled to continental Europe, as a centre of learning and scholarship, Oxfords reputation declined in the Age of Enlightenment, enrolments fell and teaching was neglected
11.
Tritium
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Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons, naturally occurring tritium is extremely rare on Earth, where trace amounts are formed by the interaction of the atmosphere with cosmic rays. It can be produced by irradiating lithium metal or lithium bearing ceramic pebbles in a nuclear reactor, the name of this isotope is derived from the Greek word τρίτος meaning third. While tritium has several different experimentally determined values of its half-life and it decays into helium-3 by beta decay as in this nuclear equation, and it releases 18.6 keV of energy in the process. The electrons kinetic energy varies, with an average of 5.7 keV, beta particles from tritium can penetrate only about 6.0 mm of air, and they are incapable of passing through the dead outermost layer of human skin. The unusually low energy released in the beta decay makes the decay appropriate for absolute neutrino mass measurements in the laboratory. The low energy of tritiums radiation makes it difficult to detect tritium-labeled compounds except by using liquid scintillation counting, Tritium is produced in nuclear reactors by neutron activation of lithium-6. This is possible with neutrons of any energy, and is an exothermic reaction yielding 4.8 MeV, in comparison, the fusion of deuterium with tritium releases about 17.6 MeV of energy. High-energy neutrons can produce tritium from lithium-7 in an endothermic reaction. This was discovered when the 1954 Castle Bravo nuclear test produced a high yield. High-energy neutrons irradiating boron-10 will also produce tritium, A more common result of boron-10 neutron capture is 7Li. The reactions requiring high neutron energies are not attractive production methods for peaceful applications, Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. This reaction has a quite small absorption cross section, making water a good neutron moderator. Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment. Ontario Power Generations Tritium Removal Facility processes up to 2,500 tonnes of water a year. Deuteriums absorption cross section for thermal neutrons is about 0.52 millibarns, whereas that of oxygen-16 is about 0.19 millibarns and that of oxygen-17 is about 240 millibarns. Tritium is a product of the nuclear fission of uranium-235, plutonium-239. The release or recovery of tritium needs to be considered in the operation of reactors, especially in the reprocessing of nuclear fuels
12.
Sector mass spectrometer
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A sector instrument is a general term for a class of mass spectrometer that uses a static electric or magnetic sector or some combination of the two as a mass analyzer. A popular combination of these sectors has been the BEB, most modern sector instruments are double-focusing instruments in that they focus the ion beams both in direction and velocity. The behavior of ions in a homogeneous, linear, static electric or magnetic field as is found in an instrument is simple. The physics are described by a single equation called the Lorentz force law. F = q, where E is the field strength, B is the magnetic field induction, q is the charge of the particle, v is its current velocity. So the force on an ion in a linear homogeous electric field is, F = q E, in the direction of the field, with positive ions. The force is dependent on the charge and electric field strength. The sector instrument geometry consists of a 127. 30° electric sector without an initial drift length followed by a 60° magnetic sector with the direction of curvature. Sometimes called a Bainbridge mass spectrometer, this configuration is used to determine isotopic masses. A beam of particles is produced from the isotope under study. The beam is subject to the action of perpendicular electric and magnetic fields. The mass of the isotope is determined through subsequent calculation, the Mattauch-Herzog geometry consists of a 31. 82° electric sector, a drift length which is followed by a 90° magnetic sector of opposite curvature direction. The entry of the ions sorted primarily by charge into the field produces an energy focussing effect. The advantage of this geometry over the Nier-Johnson geometry is that the ions of different masses are all focused onto the flat plane. This allows the use of a plate or other flat detector array. The Nier-Johnson geometry consists of a 90° electric sector, a long intermediate drift length, the Hinterberger-Konig geometry consists of a 42. 43° electric sector, a long intermediate drift length and a 130° magnetic sector of the same curvature direction. The Matsuda geometry consists of an 85° electric sector, a quadrupole lens and this geometry is used in the SHRIMP and Panorama. Mass-analyzed ion kinetic energy spectrometry Charge remote fragmentation Kenneth Bainbridge Alfred O. C
