1.
Fermilab
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Fermi National Accelerator Laboratory, located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, Fermilab is a part of the Illinois Technology and Research Corridor. Fermilabs Tevatron was a particle accelerator, at 3.9 miles in circumference, it was the worlds fourth-largest particle accelerator. In 1995, the discovery of the top quark was announced by researchers who used the Tevatrons CDF, in addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE, NOνA and SeaQuest. Completed neutrino experiments include MINOS, MINOS+, MiniBooNE and SciBooNE, the MiniBooNE detector was a 40-foot diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year, SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. In the public realm, Fermilab hosts many events, not only public science lectures and symposia. The site is open dawn to dusk to visitors who present valid photo identification. Asteroid 11998 Fermilab is named in honor of the laboratory, weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab. The laboratory was founded in 1967 as the National Accelerator Laboratory, the laboratorys first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation and he is the namesake of the sites high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus. After Wilson stepped down in 1978 to protest the lack of funding for the lab and it was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989 and remains Director Emeritus, the science education center at the site was named in his honor. The later directors include, John Peoples,1989 to 1999 Michael S, as of 2014, the first stage in the acceleration process takes place in two ion sources which turn hydrogen gas into H− ions. A magnetron generates a plasma to form the ions near the metal surface, at the exit of RFQ, the beam is matched by medium energy beam transport into the entrance of the linear accelerator. The next stage of acceleration is linear particle accelerator and this stage consists of two segments. The first segment has 5 vacuum vessel for drift tubes, operating at 201 MHz, the second stage has 7 side-coupled cavities, operating at 805 MHz. At the end of linac, the particles are accelerated to 400 MeV, immediately before entering the next accelerator, the H− ions pass through a carbon foil, becoming H+ ions
2.
Liquid hydrogen
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Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form, one common method of obtaining liquid hydrogen involves a compressor resembling a jet engine in both appearance and principle. Liquid hydrogen is used as a concentrated form of hydrogen storage. As in any gas, storing it as liquid takes less space than storing it as a gas at temperature and pressure. However, the density is very low compared to other common fuels. Once liquefied, it can be maintained as a liquid in pressurized, liquid hydrogen consists of 99. 79% parahydrogen,0. 21% orthohydrogen. In 1885 Zygmunt Florenty Wróblewski published hydrogens critical temperature as 33 K, critical pressure,13.3 atmospheres, hydrogen was liquefied by James Dewar in 1898 by using regenerative cooling and his invention, the vacuum flask. The first synthesis of the stable form of liquid hydrogen, parahydrogen, was achieved by Paul Harteck. Room–temperature hydrogen consists mostly of the orthohydrogen form, practical H2–O2 rocket engines run fuel-rich so that the exhaust contains some unburned hydrogen. This reduces combustion chamber and nozzle erosion and it also reduces the molecular weight of the exhaust which can actually increase specific impulse despite the incomplete combustion. Liquid hydrogen can be used as the fuel for an internal combustion engine or fuel cell, various submarines and concept hydrogen vehicles have been built using this form of hydrogen. Due to its similarity, builders can sometimes modify and share equipment with systems designed for LNG, however, because of the lower volumetric energy, the hydrogen volumes needed for combustion are large. Unless LH2 is injected instead of gas, hydrogen-fueled piston engines usually require larger fuel systems, unless direct injection is used, a severe gas-displacement effect also hampers maximum breathing and increases pumping losses. Liquid hydrogen is used to cool neutrons to be used in neutron scattering. Since neutrons and hydrogen nuclei have similar masses, kinetic energy exchange per interaction is maximum, finally, superheated liquid hydrogen was used in many bubble chamber experiments. The first thermonuclear bomb, Ivy Mike, used liquid deuterium, the product of its combustion with oxygen alone is water vapor, which can be cooled with some of the liquid hydrogen. Since water is harmless to the environment, an engine burning it can be considered zero emissions, liquid hydrogen also has a much higher specific energy than gasoline, natural gas, or diesel. The density of hydrogen is only 70.99 g/L
3.
Superheating
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This article is about the phenomenon where a liquid can exist in a metastable state above its boiling point. See superheated water for pressurized water above 100 °C, see superheater for the device used in steam engines. In physics, superheating is the phenomenon in which a liquid is heated to a higher than its boiling point. Superheating is achieved by heating a substance in a clean container, free of nucleation sites. Water is said to boil when bubbles of water vapor grow without bound, for a vapor bubble to expand, the temperature must be high enough that the vapor pressure exceeds the ambient pressure. Below that temperature, a vapor bubble will shrink and vanish. Superheating is an exception to this rule, a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is a force, the surface tension, which suppresses the growth of bubbles. Surface tension makes the bubble act like a rubber balloon, the pressure inside is raised slightly by the skin attempting to contract. For the bubble to expand, the temperature must be raised slightly above the point to generate enough vapor pressure to overcome both surface tension and ambient pressure. What makes superheating so explosive is that a bubble is easier to inflate than a small one, just as when blowing up a balloon. It turns out the pressure due to surface tension is inversely proportional to the diameter of the bubble. This means if the largest bubbles in a container are only a few micrometres in diameter, once a bubble does begin to grow, the pressure due to the surface tension reduces, so it expands explosively. In practice, most containers have scratches or other imperfections which trap pockets of air that provide starting bubbles, but a container of liquid with only microscopic bubbles can superheat dramatically. Superheating can occur when a container of water is heated in a microwave oven. When the container is removed, the water appears to be below the boiling point. However, once the water is disturbed, some of it violently flashes to steam, the boiling can be triggered by jostling the cup, inserting a stirring device, or adding a substance like instant coffee or sugar. The chances of superheating are greater with smooth containers, because scratches or chips can house small pockets of air, which serve as nucleation points
4.
Transparency and translucency
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In the field of optics, transparency is the physical property of allowing light to pass through the material without being scattered. On a macroscopic scale, the photons can be said to follow Snells Law, in other words, a translucent medium allows the transport of light while a transparent medium not only allows the transport of light but allows for image formation. The opposite property of translucency is opacity, transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. When light encounters a material, it can interact with it in different ways. These interactions depend on the wavelength of the light and the nature of the material, photons interact with an object by some combination of reflection, absorption and transmission. Some materials, such as glass and clean water, transmit much of the light that falls on them and reflect little of it. Many liquids and aqueous solutions are highly transparent, absence of structural defects and molecular structure of most liquids are mostly responsible for excellent optical transmission. Materials which do not transmit light are called opaque, many such substances have a chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of light frequencies. They absorb certain portions of the spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation and this is what gives rise to color. The attenuation of light of all frequencies and wavelengths is due to the mechanisms of absorption. Transparency can provide almost perfect camouflage for animals able to achieve it and this is easier in dimly-lit or turbid seawater than in good illumination. Many marine animals such as jellyfish are highly transparent, at the atomic or molecular level, physical absorption in the infrared portion of the spectrum depends on the frequencies of atomic or molecular vibrations or chemical bonds, and on selection rules. Nitrogen and oxygen are not greenhouse gases because there is no absorption because there is no molecular dipole moment. With regard to the scattering of light, the most critical factor is the scale of any or all of these structural features relative to the wavelength of the light being scattered. Primary material considerations include, Crystalline structure, whether or not the atoms or molecules exhibit the long-range order evidenced in crystalline solids, glassy structure, scattering centers include fluctuations in density or composition. Microstructure, scattering centers include internal surfaces such as boundaries, crystallographic defects
5.
Liquid
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A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a constant volume independent of pressure. As such, it is one of the four states of matter. A liquid is made up of tiny vibrating particles of matter, such as atoms, water is, by far, the most common liquid on Earth. Like a gas, a liquid is able to flow and take the shape of a container, most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, a distinctive property of the liquid state is surface tension, leading to wetting phenomena. The density of a liquid is usually close to that of a solid, therefore, liquid and solid are both termed condensed matter. On the other hand, as liquids and gases share the ability to flow, although liquid water is abundant on Earth, this state of matter is actually the least common in the known universe, because liquids require a relatively narrow temperature/pressure range to exist. Most known matter in the universe is in form as interstellar clouds or in plasma form within stars. Liquid is one of the four states of matter, with the others being solid, gas. Unlike a solid, the molecules in a liquid have a greater freedom to move. The forces that bind the molecules together in a solid are only temporary in a liquid, a liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, if liquid is placed in a bag, it can be squeezed into any shape. These properties make a suitable for applications such as hydraulics. Liquid particles are bound firmly but not rigidly and they are able to move around one another freely, resulting in a limited degree of particle mobility. As the temperature increases, the vibrations of the molecules causes distances between the molecules to increase. When a liquid reaches its point, the cohesive forces that bind the molecules closely together break. If the temperature is decreased, the distances between the molecules become smaller, only two elements are liquid at standard conditions for temperature and pressure, mercury and bromine. Four more elements have melting points slightly above room temperature, francium, caesium, gallium and rubidium, metal alloys that are liquid at room temperature include NaK, a sodium-potassium metal alloy, galinstan, a fusible alloy liquid, and some amalgams
6.
Electric charge
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Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of charges, positive and negative. Like charges repel and unlike attract, an absence of net charge is referred to as neutral. An object is charged if it has an excess of electrons. The SI derived unit of charge is the coulomb. In electrical engineering, it is common to use the ampere-hour. The symbol Q often denotes charge, early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that dont require consideration of quantum effects. The electric charge is a conserved property of some subatomic particles. Electrically charged matter is influenced by, and produces, electromagnetic fields, the interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces. 602×10−19 coulombs. The proton has a charge of +e, and the electron has a charge of −e, the study of charged particles, and how their interactions are mediated by photons, is called quantum electrodynamics. Charge is the property of forms of matter that exhibit electrostatic attraction or repulsion in the presence of other matter. Electric charge is a property of many subatomic particles. The charges of free-standing particles are integer multiples of the charge e. Michael Faraday, in his electrolysis experiments, was the first to note the discrete nature of electric charge, robert Millikans oil drop experiment demonstrated this fact directly, and measured the elementary charge. By convention, the charge of an electron is −1, while that of a proton is +1, charged particles whose charges have the same sign repel one another, and particles whose charges have different signs attract. The charge of an antiparticle equals that of the corresponding particle, quarks have fractional charges of either −1/3 or +2/3, but free-standing quarks have never been observed. The electric charge of an object is the sum of the electric charges of the particles that make it up. An ion is an atom that has lost one or more electrons, giving it a net charge, or that has gained one or more electrons
7.
Donald A. Glaser
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Donald Arthur Glaser was an American physicist, neurobiologist, and the winner of the 1960 Nobel Prize in Physics for his invention of the bubble chamber used in subatomic particle physics. Born in Cleveland, Ohio, Glaser completed his Bachelor of Science degree in physics and mathematics from Case School of Applied Science in 1946 and he completed his Ph. D. in physics from the California Institute of Technology in 1949. Glaser accepted a position as an instructor at the University of Michigan in 1949 and he joined the faculty of the University of California at Berkeley, in 1959, as a Professor of Physics. During this time his research concerned short-lived elementary particles, the bubble chamber enabled him to observe the paths and lifetimes of the particles. Starting in 1962, Glaser changed his field of research to molecular biology, in 1964, he was given the additional title of Professor of Molecular Biology. Glasers position was Professor of Physics and Neurobiology in the Graduate School, Donald Glaser was born on September 21,1926, in Cleveland, Ohio, to Russian Jewish immigrants, Lena and William J. Glaser, a businessman. He enjoyed music and played the piano, violin, and viola and he went to Cleveland Heights High School, where he became interested in physics as a means to understand the physical world. He died in his sleep at the age of 86 on February 28,2013 in Berkeley, Glaser attended Case School of Applied Science, where he completed his bachelors degree in physics and mathematics in 1946. During the course of his there, he became especially interested in particle physics. He played viola in the Cleveland Philharmonic while at Case, and he continued on to the California Institute of Technology, where he pursued his Ph. D. in physics. His interest in physics led him to work with Nobel laureate Carl David Anderson. He preferred the accessibility of cosmic ray research over that of nuclear physics, while at Caltech he learned to design and build the equipment he needed for his experiments, and this skill would prove to be useful throughout his career. He also attended molecular genetics seminars led by Nobel laureate Max Delbrück, Glaser completed his doctoral thesis, The Momentum Distribution of Charged Cosmic Ray Particles Near Sea Level, after starting as an instructor at the University of Michigan in 1949. He received his Ph. D. from Caltech in 1950, while teaching at Michigan, Glaser began to work on experiments that led to the creation of the bubble chamber. His experience with cloud chambers at Caltech had shown him that they were inadequate for studying elementary particles, in a cloud chamber, particles pass though gas and collide with metal plates that obscure the scientists view of the event. The cloud chamber also needs time to reset between recording events and cannot keep up with accelerators rate of particle production and he experimented with using superheated liquid in a glass chamber. Charged particles would leave a track of bubbles as they passed through the liquid and he created the first bubble chamber with ether. He experimented with hydrogen while visiting the University of Chicago, showing that hydrogen would also work in the chamber and his new invention was ideal for use with high-energy accelerators, so Glaser traveled to Brookhaven National Laboratory with some students to study elementary particles using the accelerator there
8.
Nobel Prize in Physics
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The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who conferred the most outstanding contributions for mankind in the field of physics. The first Nobel Prize in Physics was awarded to German/Dutch physicist Wilhelm Röntgen in recognition of the services he has rendered by the discovery of the remarkable rays. This award is administered by the Nobel Foundation and widely regarded as the most prestigious award that a scientist can receive in physics and it is presented in Stockholm at an annual ceremony on December 10, the anniversary of Nobels death. Through 2016, a total of 203 individuals have been awarded the prize, only two women have won the Nobel Prize in Physics, Marie Curie in 1903, and Maria Goeppert Mayer in 1963. Though Nobel wrote several wills during his lifetime, the last one was written a year before he died and was signed at the Swedish-Norwegian Club in Paris on 27 November 1895. Nobel bequeathed 94% of his assets,31 million Swedish kronor, to establish. Due to the level of surrounding the will, it was not until April 26,1897 that it was approved by the Storting. The executors of his will were Ragnar Sohlman and Rudolf Lilljequist, the members of the Norwegian Nobel Committee who were to award the Peace Prize were appointed shortly after the will was approved. The prize-awarding organisations followed, the Karolinska Institutet on June 7, the Swedish Academy on June 9, the Nobel Foundation then reached an agreement on guidelines for how the Nobel Prize should be awarded. In 1900, the Nobel Foundations newly created statutes were promulgated by King Oscar II, according to Nobels will, The Royal Swedish Academy of sciences were to award the Prize in Physics. A maximum of three Nobel laureates and two different works may be selected for the Nobel Prize in Physics, compared with other Nobel Prizes, the nomination and selection process for the prize in Physics is long and rigorous. This is a key reason why it has grown in importance over the years to become the most important prize in Physics, the Nobel laureates are selected by the Nobel Committee for Physics, a Nobel Committee that consists of five members elected by The Royal Swedish Academy of Sciences. In the first stage begins in September, around 3,000 people – selected university professors, Nobel Laureates in Physics and Chemistry. The completed nomination forms arrive at the Nobel Committee no later than 31 January of the following year and these nominees are scrutinized and discussed by experts who narrow it to approximately fifteen names. The committee submits a report with recommendations on the candidates into the Academy. The Academy then makes the selection of the Laureates in Physics through a majority vote. The names of the nominees are never announced, and neither are they told that they have been considered for the prize. Nomination records are sealed for fifty years, while posthumous nominations are not permitted, awards can be made if the individual died in the months between the decision of the prize committee and the ceremony in December
9.
Beer
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Beer is the worlds oldest and most widely consumed alcoholic drink, it is the third most popular drink overall, after water and tea. Most beer is flavoured with hops, which add bitterness and act as a natural preservative, the fermentation process causes a natural carbonation effect, although this is often removed during processing, and replaced with forced carbonation. Beer is sold in bottles and cans, it may also be available on draught, particularly in pubs, the brewing industry is a global business, consisting of several dominant multinational companies and many thousands of smaller producers ranging from brewpubs to regional breweries. The strength of beer is usually around 4% to 6% alcohol by volume, archaeologists speculate that beer was instrumental in the formation of civilisations. Approximately 5000 years ago, workers in the city of Uruk were paid by their employers in beer, the earliest known chemical evidence of barley beer dates to circa 3500–3100 BC from the site of Godin Tepe in the Zagros Mountains of western Iran. The Ebla tablets, discovered in 1974 in Ebla, Syria, a fermented beverage using rice and fruit was made in China around 7000 BC. Unlike sake, mould was not used to saccharify the rice, almost any substance containing sugar can naturally undergo alcoholic fermentation. It is likely that many cultures, on observing that a liquid could be obtained from a source of starch. Bread and beer increased prosperity to a level that allowed time for development of other technologies, Beer was spread through Europe by Germanic and Celtic tribes as far back as 3000 BC, and it was mainly brewed on a domestic scale. The product that the early Europeans drank might not be recognised as beer by most people today, alongside the basic starch source, the early European beers might contain fruits, honey, numerous types of plants, spices and other substances such as narcotic herbs. What they did not contain was hops, as that was an addition, first mentioned in Europe around 822 by a Carolingian Abbot. Beer produced before the Industrial Revolution continued to be made and sold on a scale, although by the 7th century AD, beer was also being produced. During the Industrial Revolution, the production of beer moved from artisanal manufacture to industrial manufacture, the development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process and greater knowledge of the results. Today, the industry is a global business, consisting of several dominant multinational companies. As of 2006, more than 133 billion litres, the equivalent of a cube 510 metres on a side, of beer are sold per year, the process of making beer is known as brewing. A dedicated building for the making of beer is called a brewery, a company that makes beer is called either a brewery or a brewing company. Beer made on a scale for non-commercial reasons is classified as homebrewing regardless of where it is made. Brewing beer is subject to legislation and taxation in developed countries, however, the UK government relaxed legislation in 1963, followed by Australia in 1972 and the US in 1978, allowing homebrewing to become a popular hobby
10.
Prototype
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A prototype is an early sample, model, or release of a product built to test a concept or process or to act as a thing to be replicated or learned from. It is a used in a variety of contexts, including semantics, design, electronics. A prototype is used to evaluate a new design to enhance precision by system analysts. Prototyping serves to provide specifications for a real, working system rather than a theoretical one, in some design workflow models, creating a prototype is the step between the formalization and the evaluation of an idea. The word prototype derives from the Greek πρωτότυπον prototypon, primitive form, neutral of πρωτότυπος prototypos, original, primitive, from πρῶτος protos, first and τύπος typos, a Working Prototype represents all or nearly all of the functionality of the final product. A Visual Prototype represents the size and appearance, but not the functionality, a User Experience Prototype represents enough of the appearance and function of the product that it can be used for user research. A Functional Prototype captures both function and appearance of the design, though it may be created with different techniques. A Paper Prototype is a printed or hand-drawn representation of the interface of a software product. In some cases, the final production materials may still be undergoing development themselves, process - Mass-production processes are often unsuitable for making a small number of parts, so prototypes may be made using different fabrication processes than the final product. Differences in fabrication process may lead to differences in the appearance of the prototype as compared to the final product, verification - The final product may be subject to a number of quality assurance tests to verify conformance with drawings or specifications. These tests may involve custom inspection fixtures, statistical sampling methods, prototypes are generally made with much closer individual inspection and the assumption that some adjustment or rework will be part of the fabrication process. Prototypes may also be exempted from some requirements that apply to the final product. Engineers and prototype specialists will attempt to minimize the impact of these differences on the role for the prototype. Engineers and prototyping specialists seek to understand the limitations of prototypes to exactly simulate the characteristics of their intended design and it is important to realize that by their very definition, prototypes will represent some compromise from the final production design. Due to differences in materials, processes and design fidelity, it is possible that a prototype may fail to perform acceptably whereas the design may have been sound. In general, it can be expected that individual prototype costs will be greater than the final production costs due to inefficiencies in materials. Prototypes are also used to revise the design for the purposes of reducing costs through optimization and it is possible to use prototype testing to reduce the risk that a design may not perform as intended, however prototypes generally cannot eliminate all risk. As an alternative, rapid prototyping or rapid application development techniques are used for the prototypes, which implement part
11.
Cloud chamber
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The cloud chamber, also known as the Wilson chamber, is a particle detector used for detecting ionizing radiation. In its most basic form, a chamber is a sealed environment containing a supersaturated vapor of water or alcohol. When a charged particle interacts with the mixture, the fluid is ionized, the resulting ions act as condensation nuclei, around which a mist will form. The high energies of alpha and beta particles mean that a trail is left, Cloud chambers played a prominent role in the experimental particle physics from the 1920s to the 1950s, until the advent of the bubble chamber. In particular, the discoveries of the positron in 1932, the muon in 1936, Anderson detected the positron and muon in cosmic rays. Charles Thomson Rees Wilson, a Scottish physicist, is credited with inventing the cloud chamber, inspired by sightings of the Brocken spectre while working on the summit of Ben Nevis in 1894, he began to develop expansion chambers for studying cloud formation and optical phenomena in moist air. Very rapidly he discovered that ions could act as centers for water droplet formation in such chambers and he pursued the application of this discovery and perfected the first cloud chamber in 1911. When an ionizing particle passes through the chamber, water condenses on the resulting ions. Wilson, along with Arthur Compton, received the Nobel Prize in Physics in 1927 for his work on the cloud chamber and this kind of chamber is also called a Pulsed Chamber because the conditions for operation are not continuously maintained. Further developments were made by Patrick Blackett who utilised a stiff spring to expand and compress the chamber very rapidly, a cine film was used to record the images. The diffusion cloud chamber was developed in 1936 by Alexander Langsdorf, instead of water vapor, alcohol is used because of its lower freezing point. Cloud chambers cooled by dry ice are a demonstration and hobbyist device. There are also water-cooled diffusion cloud chambers, using ethylene glycol, a simple cloud chamber consists of the sealed environment, radioactive source, dry ice or a cold plate and some kind of alcohol source. The alcohol falls as it cools down and the cold condenser provides a steep temperature gradient, the result is a supersaturated environment. The alcohol vapor condenses around ion trails left behind by the travelling ionizing particles, the result is cloud formation, seen in the cloud chamber by the presence of droplets falling down to the condenser. As particles pass through they leave ionization trails and because the vapor is supersaturated it condenses onto these trails. Since the tracks are emitted radially out from the source, their point of origin can easily be determined, just above the cold condenser plate there is an area of the chamber which is sensitive to radioactive tracks. At this height, most of the alcohol has not condensed and this means that the ion trail left by the radioactive particles provides an optimal trigger for condensation and cloud formation
12.
Supersaturation
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Supersaturation is a state of a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances. It can also refer to a vapor of a compound that has a higher pressure than the pressure of that compound. Special conditions need to be met in order to generate a supersaturated solution, one of the easiest ways to do this relies on the temperature dependence of solubility. As a general rule, the heat is added to a system. Therefore, at high temperatures, more solute can be dissolved than at room temperature, the precipitation or crystallization of the solute takes longer than the actual cooling time because the molecules need to meet up and form the precipitate without being knocked apart by water. Thus, the larger the molecule, the longer it will take to crystallize due to the principles of Brownian motion, the condition of supersaturation does not necessarily have to be reached through the manipulation of heat. The ideal gas law suggests that pressure and volume can also be changed to force a system into a supersaturated state, if the volume of solvent is decreased, the concentration of the solute can be above the saturation point and thus create a supersaturated solution. The decrease in volume is most commonly generated through evaporation, similarly, an increase in pressure can drive a solution to a supersaturated state. All three of these rely on the fact that the conditions of the solution can be changed quicker than the solute can precipitate or crystallize out. Supersaturated solutions will also undergo crystallization under specific conditions, in a normal solution, once the maximum amount of solute is dissolved, adding more solute would either cause the dissolved solute to precipitate out and/or for the solute to not dissolve at all. Similarly, there are cases wherein solubility of a solution is decreased by manipulating temperature, pressure, or volume. In these cases, the solute will simply precipitate out and this is due to the fact that a supersaturated solution is in a higher energy state than a saturated solution. Crystallization will occur to allow the solution to reach an energy state. The activation energy comes in the form of a crystal being added to the liquid solution. This nuclei can be added from another source, which is known as seeding, or can spontaneously form within the solution due partly to ion. This process is known as primary nucleation and it is necessary for the nuclei to be identical to the solute that is crystallizing. This will allow for the ions to build up on the nuclei. There are a multitude of factors that affect the rate and order of magnitude with which crystallization proceeds as well as the difference in formation of crystallites
13.
Wire chamber
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The multi-wire chamber uses an array of wires at high voltage, which run through a chamber with conductive walls held at ground potential. The chamber is filled with carefully chosen gas, such as an argon/methane mix, the resulting ions and electrons are accelerated by the electric field across the chamber, causing a localised cascade of ionization known as a Townsend avalanche. This collects on the nearest wire and results in a proportional to the ionisation effect of the detected particle. By computing pulses from all the wires, the trajectory can be found. Adaptions of this design are the thin gap, resistive plate. The drift chamber is also sub-divided into ranges of use in the chamber designs known as time projection, microstrip gas. In 1968, Georges Charpak, while at the European Organization for Nuclear Research in CERN, the chamber was an advancement of the earlier bubble chamber rate of detection of only one or two particles every second to 1000 particle detections every second. The MWPC produced electronic signals from particle detection allowing scientists to examine data via computers, the multi-wire chamber is a development of the spark chamber. For high energy experiments, it is used to observe a particles path. For a long time, bubble chambers were used for this purpose, a wire chamber is a chamber with many parallel wires, arranged as a grid and put on high voltage, with the metal casing being on ground potential. As in the Geiger counter, a particle leaves a trace of ions and electrons, by marking off the wires which had a pulse of current, one can see the particles path. The chamber has a very good time resolution, good positional accuracy. This greatly increases the accuracy of the reconstruction and is known as a drift chamber. Design is similar to the Mw chamber but instead with central layer wires at a distance apart. The detection of charged particles within the chamber is possible by the ionizing of particles of gas due to the motion of the charged particle, the Fermilab detector CDF II contains a drift chamber called the Central Outer Tracker. The chamber contains argon and ethane gas, and wires separated by 3.56 millimetres gaps. If two drift chambers are used with the wires of one orthogonal to the wires of the other, particle Detectors hypermail_ archive of links to CLAS drift chambers Heidelberg lecture on research ionisation chambers
14.
Spark chamber
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A spark chamber is a particle detector. A particle detector is a used in particle physics for detecting electrically charged particles. They were most widely used as research tools from the 1930s to the 1960s and have since superseded by other technologies such as drift chambers. Today, working spark chambers are mostly found in museums and educational organisations. Spark chambers consist of a stack of metal placed in a sealed box filled with a gas such as helium. When a charged particle from a cosmic ray travels through the box, ordinarily this ionisation would remain invisible. In order to control when this voltage is applied, a detector is needed. When this trigger senses that a cosmic ray has just passed, the high voltage cannot be connected to the plates permanently, as this would lead to arc formation and continuous discharging. As research devices, spark chamber detectors have lower resolution than bubble chamber detectors, however they can be made highly selective with the help of auxiliary detectors, making them useful in searching for very rare events. Streamer chambers are a different type of detector, closely related to spark chambers, in a spark chamber one looks at a stack of parallel plates edge-on. For this reason, best viewing is afforded when the comes in perpendicularly to the plates. A streamer chamber, in contrast, typically has two plates, at least one of which is transparent. Particles come in roughly parallel to the plane of these plates, a much shorter high-voltage pulse is used than with a spark chamber, so there is insufficient time for sparks to form. Instead very dim streamers of ionised gas are formed and these can be seen when image enhancement is applied. Electric spark Cloud Chamber Bubble Chamber University of Cambridge Spark Chambers Spark Chamber Project - McGill University How does a spark chamber work, - From an exhibitor at the 2011 Royal Society Summer Science Exhibition. How does a spark chamber work, - University of Birmingham Enhanced image of streamers taken in a steamer chamber
15.
Big European Bubble Chamber
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The Big European Bubble Chamber is a large size detector formerly used to study particle physics at CERN. The liquids at typical operation temperatures around 27 K were placed under overpressure of about 5 atm and these bubbles tracks were photographed by the five cameras mounted on top of the chamber. The stereo photographs were subsequently scanned and all events finally evaluated by a team of scientists, after each expansion, the pressure was increased again to stop the boiling. The bubble chamber was then again for a new cycle of particles beam exposure. The BEBC project was launched in 1966 by CERN, France and Germany, the chamber body was surrounded by the then largest superconducting solenoid magnet of two coils in Helmholtz arrangement. The magnet coils were fabricated at CERN using copper reinforced Niob-Titanium superconductor cable, the BEBC coils created a strong magnetic field of 3.5 T over the sensitive volume of the chamber. Thus, the fast charged particles passing through the chamber were bent in the field which provided information on their momentum. The first images were recorded in 1973 when BEBC first received beam from the Proton Synchrotron, from 1977 to 1984, the chamber took photos in the West Area neutrino beam line of the Super Proton Synchrotron and in hadron beams at energies of up to 450 GeV. During 1978, a Track-Sensitive Target was installed to combine the advantages of hydrogen, hydrogen-filled chambers enable the study of particle interactions with free protons but they have a low efficiency for gamma ray conversion. On the other hand, heavy liquid filling is better suited for the detection of gamma rays, an External Muon Identifier and an External Particle Identifier were added to the BEBC, in 1979, to identify muons and charged hadrons, respectively, leaving the chamber. Furthermore, an Internal Picket Fence was used to obtain timing signals for events occurring in the bubble chamber helping to suppress the background and these changes transformed BEBC into a hybrid detector. The BEBC experiments were, T225/231, T243, WA17, WA19, WA20, WA21, WA22, W24, WA25, WA26, WA27, WA28, WA30, WA31, WA32, WA47, WA51, WA52, WA59, WA66, WA73 and PS180. By the end of its life in 1984, BEBC had delivered a total of 6.3 million photographs to 22 experiments. Around 600 scientists from some fifty laboratories throughout the world had taken part in analyzing the 3000 km of film it had produced, BECB enabled the discovery of D-mesons and promoted the developments of neutrino and hadron physics carrying out one of the richest physics programs. It is now on display at CERNs Microcosm museum
16.
Gargamelle
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Gargamelle was a giant bubble chamber detector at CERN, designed mainly for the detection of neutrino interactions. Built in France, with a diameter of nearly 2 meters and 4.8 meters in length, the usage of a heavy liquid, rather than the more typical liquid hydrogen, meant higher neutrino interaction probability, as well as easier identification of muons versus pions. Gargamelle operated from 1970 to 1978 with a neutrino beam produced by the CERN Proton Synchrotron. For the experiment, approximately 83,000 neutrino events were analysed, the signature of a neutral current event was an isolated vertex from which only hadrons were produced. The name of the chamber derives from the giantess Gargamelle in the works of François Rabelais, the road to unification – Gargamelle and the discovery of Weak Neutral Currents Padilla, Antonio. Brady Haran for the University of Nottingham
17.
Boiling point
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The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the environmental pressure. A liquid in a vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a boiling point than when that liquid is at atmospheric pressure. For a given pressure, different liquids boil at different temperatures, for example, water boils at 100 °C at sea level, but at 93.4 °C at 2,000 metres altitude. The normal boiling point of a liquid is the case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level,1 atmosphere. At that temperature, the pressure of the liquid becomes sufficient to overcome atmospheric pressure. The standard boiling point has been defined by IUPAC since 1982 as the temperature at which boiling occurs under a pressure of 1 bar, the heat of vaporization is the energy required to transform a given quantity of a substance from a liquid into a gas at a given pressure. Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation, evaporation is a surface phenomenon in which molecules located near the liquids edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, a saturated liquid contains as much thermal energy as it can without boiling. The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase, the liquid can be said to be saturated with thermal energy. Any addition of energy results in a phase transition. If the pressure in a system remains constant, a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy is removed, similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied. The boiling point corresponds to the temperature at which the pressure of the liquid equals the surrounding environmental pressure. Thus, the point is dependent on the pressure. Boiling points may be published with respect to the NIST, USA standard pressure of 101.325 kPa, at higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, the boiling point cannot be increased beyond the critical point. Likewise, the point decreases with decreasing pressure until the triple point is reached
18.
Piston
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A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder, in some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder wall. An internal combustion engine is acted upon by the pressure of the combustion gases in the combustion chamber space at the top of the cylinder. This force then acts downwards through the rod and onto the crankshaft. The connecting rod is attached to the piston by a swivelling gudgeon pin and this pin is mounted within the piston, unlike the steam engine, there is no piston rod or crosshead. The pin itself is of hardened steel and is fixed in the piston, a few designs use a fully floating design that is loose in both components. All pins must be prevented from moving sideways and the ends of the pin digging into the cylinder wall, gas sealing is achieved by the use of piston rings. These are a number of iron rings, fitted loosely into grooves in the piston. The rings are split at a point in the rim, allowing them to press against the cylinder with a light spring pressure. Two types of ring are used, the rings have solid faces and provide gas sealing, lower rings have narrow edges. There are many proprietary and detail design features associated with piston rings, pistons are cast from aluminium alloys. For better strength and fatigue life, some racing pistons may be forged instead, early pistons were of cast iron, but there were obvious benefits for engine balancing if a lighter alloy could be used. To produce pistons that could survive engine combustion temperatures, it was necessary to develop new alloys such as Y alloy and Hiduminium, a few early gas engines had double-acting cylinders, but otherwise effectively all internal combustion engine pistons are single-acting. During World War II, the US submarine Pompano was fitted with a prototype of the infamously unreliable H. O. R, although compact, for use in a cramped submarine, this design of engine was not repeated. Media related to Internal combustion engine pistons at Wikimedia Commons Trunk pistons are long relative to their diameter and they act both as a piston and cylindrical crosshead. As the connecting rod is angled for much of its rotation, a longer piston helps to support this
19.
Metastability
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In physics, metastability denotes the phenomenon when a dynamical system spends an extended time in a configuration other than the systems state of least energy. During a metastable state of finite lifetime, all state-describing parameters reach, a conceptual analogy may be drawn with a ball resting in a hollow on a slope. Small perturbations will result in the ball settling back into its current hollow, isomerisation is another common example of metastability. Higher energy isomers are long lived as they are prevented from rearranging to their ground state by barriers in the potential energy. The metastability concept originated in the physics of first-order phase transitions and it then acquired new meaning in the study of aggregated subatomic particles or in molecules, macromolecules or clusters of atoms and molecules. Later, it was borrowed for the study of decision-making and information transmission systems, many complex natural and man-made systems can demonstrate metastability. Metastability is common in physics and chemistry – from an atom to statistical ensembles of molecules at molecular levels or as a whole, the abundance of states is more prevalent as the systems grow larger and/or if the forces of their mutual interaction are spatially less uniform or more diverse. In these systems, the equivalent of thermal fluctuations in molecular systems is the noise that affects signal propagation. Non-equilibrium thermodynamics is a branch of physics that studies the dynamics of statistical ensembles of molecules via unstable states, being stuck in a thermodynamic trough without being at the lowest energy state is known as having kinetic stability or being kinetically persistent. The particular motion or kinetics of the atoms involved has resulted in getting stuck, metastable states of matter range from melting solids, boiling liquids and sublimating solids to supercooled liquids or superheated liquid-gas mixtures. Extremely pure, supercooled water stays liquid below 0 °C and remains so until applied vibrations or condensing seed doping initiates crystallization centers and this is a common situation for the droplets of atmospheric clouds. Metastable phases are common in condensed matter, for example, diamond is a metastable form of carbon at standard temperature and pressure. It can be converted to graphite, but only after overcoming an activation energy – an intervening hill, martensite is a metastable phase used to control the hardness of most steel. The bonds between the blocks of polymers such as DNA, RNA and proteins are also metastable. Metastable polymorphs of silica are commonly observed, in some cases, such as in the allotropes of solid boron, acquiring a sample of the stable phase is difficult. Generally speaking, emulsions/colloidal systems and glasses are metastable, sandpiles are one system which can exhibit metastability if a steep slope or tunnel is present. Sand grains form a pile due to friction and it is possible for an entire large sand pile to reach a point where it is stable, but the addition of a single grain causes large parts of it to collapse. The avalanche is a problem with large piles of snow
20.
Bubble (physics)
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A bubble is a globule of one substance in another, usually gas in a liquid. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance. g, for the physics and chemistry behind it, see nucleation. Humans can see bubbles because they have a different refractive index than the surrounding substance, for example, the IR of air is approximately 1.0003 and the IR of water is approximately 1.333. Nucleation can be induced, for example to create bubblegram. In medical ultrasound imaging, small encapsulated bubbles called contrast agent are used to enhance the contrast, in thermal inkjet printing, vapor bubbles are used as actuators. They are occasionally used in microfluidics applications as actuators. The violent collapse of bubbles near solid surfaces and the resulting impinging jet constitute the mechanism used in ultrasonic cleaning, the same effect, but on a larger scale, is used in focused energy weapons such as the bazooka and the torpedo. Pistol shrimp also use a collapsing cavitation bubble as a weapon, the same effect is used to treat kidney stones in a lithotripter. Marine mammals such as dolphins and whales use bubbles for entertainment or as hunting tools, aerators cause dissolution of gas in the liquid by injecting bubbles. Chemical and metallurgic engineers rely on bubbles for operations such as distillation, absorption, flotation, the complex processes involved often require consideration for mass and heat transfer, and are modelled using fluid dynamics. The star-nosed mole and the American water shrew can smell underwater by breathing through their nostrils. When bubbles are disturbed, they pulsate at their natural frequency, large bubbles undergo adiabatic pulsations, which means that no heat is transferred either from the liquid to the gas or vice versa. The damage can be due to deformation of tissues due to bubble growth in situ. This can occur as a result of decompression after hyperbaric exposure, a lung overexpansion injury, during intravenous fluid administration, or during surgery
21.
Helix
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A helix is a type of smooth space curve, i. e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a line called the axis. Examples of helices are coil springs and the handrails of spiral staircases, a filled-in helix – for example, a spiral ramp – is called a helicoid. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices, the word helix comes from the Greek word ἕλιξ, twisted, curved. Helices can be either right-handed or left-handed, handedness is a property of the helix, not of the perspective, a right-handed helix cannot be turned to look like a left-handed one unless it is viewed in a mirror, and vice versa. Most hardware screw threads are right-handed helices, the alpha helix in biology as well as the A and B forms of DNA are also right-handed helices. The Z form of DNA is left-handed, the pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two helices with the axis, differing by a translation along the axis. A conic helix may be defined as a spiral on a conic surface, an example is the Corkscrew roller coaster at Cedar Point amusement park. A circular helix, has constant band curvature and constant torsion, a curve is called a general helix or cylindrical helix if its tangent makes a constant angle with a fixed line in space. A curve is a general helix if and only if the ratio of curvature to torsion is constant, a curve is called a slant helix if its principal normal makes a constant angle with a fixed line in space. It can be constructed by applying a transformation to the frame of a general helix. Some curves found in nature consist of multiple helices of different handedness joined together by transitions known as tendril perversions, in mathematics, a helix is a curve in 3-dimensional space. The following parametrisation in Cartesian coordinates defines a particular helix, Probably the simplest equations for one is x = cos , y = sin , z = t. As the parameter t increases, the point traces a right-handed helix of pitch 2θ and radius 1 about the z-axis, in cylindrical coordinates, the same helix is parametrised by, r =1, θ = t, h = t. A circular helix of radius a and slope b/a is described by the following parametrisation, another way of mathematically constructing a helix is to plot the complex-valued function exi as a function of the real number x. The value of x and the real and imaginary parts of the function value give this plot three real dimensions, except for rotations, translations, and changes of scale, all right-handed helices are equivalent to the helix defined above. The equivalent left-handed helix can be constructed in a number of ways, in music, pitch space is often modeled with helices or double helices, most often extending out of a circle such as the circle of fifths, so as to represent octave equivalency
22.
Mass-to-charge ratio
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The mass-to-charge ratio is a physical quantity that is most widely used in the electrodynamics of charged particles, e. g. in electron optics and ion optics. It appears in the fields of electron microscopy, cathode ray tubes, accelerator physics, nuclear physics, Auger electron spectroscopy, cosmology. In rare occasions the thomson has been used as its unit in the field of mass spectrometry, some fields use the charge-to-mass ratio instead, which is the multiplicative inverse of the mass-to-charge ratio. The 2014 CODATA recommended value for an electron is e⁄me =1. 758820024×1011 C/kg and this differential equation is the classic equation of motion for charged particles. Together with the initial conditions, it completely determines the particles motion in space. Thus mass spectrometers could be thought of as mass-to-charge spectrometers, when presenting data in a mass spectrum, it is common to use the dimensionless m/z, which denotes the dimensionless quantity formed by dividing the mass number of the ion by its charge number. Combining the two equations yields, a = E + v × B. This differential equation is the equation of motion of a charged particle in vacuum. Together with the initial conditions it determines the particles motion in space. It immediately reveals that two particles with the same m/Q ratio behave in the same way and this is why the mass-to-charge ratio is an important physical quantity in those scientific fields where charged particles interact with magnetic or electric fields. There are non-classical effects that derive from quantum mechanics, such as the Stern–Gerlach effect that can diverge the path of ions of identical m/Q. The IUPAC recommended symbol for mass and charge are m and Q, respectively, charge is a scalar property, meaning that it can be either positive or negative. The Coulomb is the SI unit of charge, however, other units can be used, the SI unit of the physical quantity m/Q is kilograms per coulomb. The units and notation above are used when dealing with the physics of mass spectrometry, however and this notation eases data interpretation since it is numerically more related to the unified atomic mass unit. The m refers to the molecular or atomic number and z to the charge number of the ion, however. An ion of 100 atomic mass units carrying two charges will be observed at m/z =50, in the 19th century, the mass-to-charge ratios of some ions were measured by electrochemical methods. In 1897, the ratio of the electron was first measured by J. J. Thomson. By doing this, he showed that the electron was in fact a particle with a mass and a charge, in 1898, Wilhelm Wien separated ions according to their mass-to-charge ratio with an ion optical device with superimposed electric and magnetic fields
23.
Electron
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The electron is a subatomic particle, symbol e− or β−, with a negative elementary electric charge. Electrons belong to the first generation of the lepton particle family, the electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the include a intrinsic angular momentum of a half-integer value, expressed in units of the reduced Planck constant. As it is a fermion, no two electrons can occupy the same state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of particles and waves, they can collide with other particles and can be diffracted like light. Since an electron has charge, it has an electric field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law, electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields, special telescopes can detect electron plasma in outer space. Electrons are involved in applications such as electronics, welding, cathode ray tubes, electron microscopes, radiation therapy, lasers, gaseous ionization detectors. Interactions involving electrons with other particles are of interest in fields such as chemistry. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms, ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of a quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge electron in 1891, electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of isotopes and in high-energy collisions. The antiparticle of the electron is called the positron, it is identical to the electron except that it carries electrical, when an electron collides with a positron, both particles can be totally annihilated, producing gamma ray photons. The ancient Greeks noticed that amber attracted small objects when rubbed with fur, along with lightning, this phenomenon is one of humanitys earliest recorded experiences with electricity. In his 1600 treatise De Magnete, the English scientist William Gilbert coined the New Latin term electricus, both electric and electricity are derived from the Latin ēlectrum, which came from the Greek word for amber, ἤλεκτρον
24.
Momentum
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In classical mechanics, linear momentum, translational momentum, or simply momentum is the product of the mass and velocity of an object, quantified in kilogram-meters per second. It is dimensionally equivalent to impulse, the product of force and time, Newtons second law of motion states that the change in linear momentum of a body is equal to the net impulse acting on it. If the truck were lighter, or moving slowly, then it would have less momentum. Linear momentum is also a quantity, meaning that if a closed system is not affected by external forces. In classical mechanics, conservation of momentum is implied by Newtons laws. It also holds in special relativity and, with definitions, a linear momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory. It is ultimately an expression of one of the symmetries of space and time. Linear momentum depends on frame of reference, observers in different frames would find different values of linear momentum of a system. But each would observe that the value of linear momentum does not change with time, momentum has a direction as well as magnitude. Quantities that have both a magnitude and a direction are known as vector quantities, because momentum has a direction, it can be used to predict the resulting direction of objects after they collide, as well as their speeds. Below, the properties of momentum are described in one dimension. The vector equations are almost identical to the scalar equations, the momentum of a particle is traditionally represented by the letter p. It is the product of two quantities, the mass and velocity, p = m v, the units of momentum are the product of the units of mass and velocity. In SI units, if the mass is in kilograms and the velocity in meters per second then the momentum is in kilogram meters/second, in cgs units, if the mass is in grams and the velocity in centimeters per second, then the momentum is in gram centimeters/second. Being a vector, momentum has magnitude and direction, for example, a 1 kg model airplane, traveling due north at 1 m/s in straight and level flight, has a momentum of 1 kg m/s due north measured from the ground. The momentum of a system of particles is the sum of their momenta, if two particles have masses m1 and m2, and velocities v1 and v2, the total momentum is p = p 1 + p 2 = m 1 v 1 + m 2 v 2. If all the particles are moving, the center of mass will generally be moving as well, if the center of mass is moving at velocity vcm, the momentum is, p = m v cm. This is known as Eulers first law, if a force F is applied to a particle for a time interval Δt, the momentum of the particle changes by an amount Δ p = F Δ t
25.
Electroweak interaction
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In particle physics, the electroweak interaction is the unified description of two of the four known fundamental interactions of nature, electromagnetism and the weak interaction. Although these two forces appear very different at low energies, the theory models them as two different aspects of the same force. Above the unification energy, on the order of 246 GeV, thus, if the universe is hot enough, then the electromagnetic force and weak force merge into a combined electroweak force. During the electroweak epoch, the electroweak force separated from the strong force, during the quark epoch, the electroweak force split into the electromagnetic and weak force. In 1999, Gerardus t Hooft and Martinus Veltman were awarded the Nobel prize for showing that the theory is renormalizable. Mathematically, the unification is accomplished under an SU × U gauge group, the corresponding gauge bosons are the three W bosons of weak isospin from SU, and the B boson of weak hypercharge from U, respectively, all of which are massless. In the Standard Model, the W± and Z0 bosons, UY and Uem are different copies of U, the generator of Uem is given by Q = Y/2 + I3, where Y is the generator of UY, and I3 is one of the SU generators. The spontaneous symmetry breaking makes the W3 and B bosons coalesce into two different bosons – the Z0 boson, and the photon, = Where θW is the mixing angle. The axes representing the particles have essentially just been rotated, in the plane and this also introduces a mismatch between the mass of the Z0 and the mass of the W± particles, M Z = M W cos θ W. The W1 and W2 bosons, in turn, combine to give massive charged bosons W ± =12, the Lagrangian for the electroweak interactions is divided into four parts before electroweak symmetry breaking L E W = L g + L f + L h + L y. The L g term describes the interaction between the three W particles and the B particle, L f is the kinetic term for the Standard Model fermions. The interaction of the bosons and the fermions are through the gauge covariant derivative. The h term describes the Higgs field F. L h = | D μ h |2 − λ2 The y term gives the Yukawa interaction that generates the masses after the Higgs acquires a nonzero vacuum expectation value. The Lagrangian reorganizes itself after the Higgs boson acquires a vacuum expectation value, due to its complexity, this Lagrangian is best described by breaking it up into several parts as follows. The neutral current L N and charged current L C components of the Lagrangian contain the interactions between the fermions and gauge bosons, the charged current part of the Lagrangian is given by L C = − g 2 W μ + + h. c. L H contains the Higgs three-point and four-point self interaction terms, L H = − g m H24 m W H3 − g 2 m H232 m W2 H4 L H V contains the Higgs interactions with gauge vector bosons. L H V = L W W V contains the gauge three-point self interactions. L Y = − ∑ f g m f 2 m W f ¯ f H Note the 1 − γ52 factors in the weak couplings and this is why electroweak theory is commonly said to be a chiral theory
26.
W and Z bosons
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The W and Z bosons are together known as the weak or more generally as the intermediate vector bosons. These elementary particles mediate the interaction, the respective symbols are W+, W−. The W bosons have either a positive or negative charge of 1 elementary charge and are each others antiparticles. The Z boson is electrically neutral and is its own antiparticle, the three particles have a spin of 1. The W bosons have a moment, but the Z has none. All three of these particles are very short-lived, with a half-life of about 3×10−25 s and their experimental discovery was a triumph for what is now known as the Standard Model of particle physics. The W bosons are named after the weak force, the physicist Steven Weinberg named the additional particle the Z particle, and later gave the explanation that it was the last additional particle needed by the model. The W bosons had already named, and the Z bosons have zero electric charge. The two W bosons are verified mediators of neutrino absorption and emission, during these processes, the W boson charge induces electron or positron emission or absorption, thus causing nuclear transmutation. The Z boson is not involved in the absorption or emission of electrons and positrons, the Z boson mediates the transfer of momentum, spin and energy when neutrinos scatter elastically from matter. Such behavior is almost as common as inelastic neutrino interactions and may be observed in bubble chambers upon irradiation with neutrino beams, in this process, the neutrino simply strikes the electron and then scatters away from it, transferring some of the neutrinos momentum to the electron. Thus, this requires a Z boson. These bosons are among the heavyweights of the elementary particles, with masses of 80.4 GeV/c2 and 91.2 GeV/c2, respectively, the W and Z bosons are almost 100 times as large as the proton – heavier, even, than entire iron atoms. The masses of these bosons are significant because they act as the carriers of a quite short-range fundamental force. By way of contrast, the force has an infinite range, because its force carrier, the photon, has zero mass. All three bosons have particle spin s =1, the emission of a W+ or W− boson either raises or lowers the electric charge of the emitting particle by one unit, and also alters the spin by one unit. At the same time, the emission or absorption of a W boson can change the type of the particle – for example changing a strange quark into an up quark. The neutral Z boson cannot change the charge of any particle
27.
UA1 experiment
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The UA1 experiment was a high-energy physics experiment that ran at CERNs Super Proton Synchrotron accelerator-collider from 1981 until 1993. The discovery of the W and Z bosons by this experiment, the UA1 central detector was crucial to understanding the complex topology of proton-antiproton events. It played a most important role in identifying a handful of Ws, the UA1 was a huge and complex detector for its day. It was designed as a general-purpose detector, the detector was a 6-chamber cylindrical assembly 5.8 m long and 2.3 m in diameter, the largest imaging drift chamber of its day. It recorded the tracks of charged particles curving in a 0.7 Tesla magnetic field, measuring their momentum, atoms in the argon-ethane gas mixture filling the chambers were ionised by the passage of charged particles. The electrons which were released drifted along an electric field shaped by field wires and were collected on sense wires, the geometrical arrangement of the 17000 field wires and 6125 sense wires allowed a spectacular 3-D interactive display of reconstructed physics events to be produced. The UA1 detector was conceived and designed in 1978/9, with the proposal submitted in mid-1978, UA2 experiment List of Super Proton Synchrotron experiments UA1 magnet sets off for a second new life. The W and Z Particles, A Personal Recollection, neutral currents and W and Z, a celebration. Image of- UA1 detector image of-central part of UA1 detector The-central
28.
Weakly interacting massive particles
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Weakly interacting massive particles are hypothetical particles that are thought to constitute dark matter. A WIMP must also have been produced thermally in the early Universe, similarly to the particles of the model according to Big Bang cosmology. WIMP-like particles are predicted by universal extra dimension and little Higgs theories. Because of their lack of interaction with normal matter, WIMPs would be dark. Because of their mass, they would be relatively slow moving. Their relatively low velocities would be insufficient to overcome the mutual gravitational attraction, WIMPs are considered one of the main candidates for cold dark matter, the others being massive compact halo objects and axions. Also, in contrast to MACHOs, there are no known stable particles within the model of particle physics that have all the properties of WIMPs. The particles that have little interaction with matter, such as neutrinos, are all very light. Although the existence of WIMP in nature is hypothetical at this point, there is near consensus today among astronomers that most of the mass in the Universe is dark. Simulations of a full of cold dark matter produce galaxy distributions that are roughly similar to what is observed. By contrast, hot dark matter would smear out the structure of galaxies. The WIMP fits the model of a dark matter particle from the early Universe. As the Universe expanded and cooled, the thermal energy of these lighter particles decreased. The annihilation of the dark matter particle-antiparticle pairs, however, would have continued, particles with a larger interaction cross section would continue to annihilate for a longer period of time, and thus would have a smaller number density when the annihilation interaction ceases. If this model is correct, the dark matter particle would have the properties of the WIMP, because WIMPs may only interact through gravitational and weak forces, they are extremely difficult to detect. However, there are many experiments underway to attempt to detect WIMPs both directly and indirectly, indirect detection refers to the observation of annihilation or decay products of WIMPs far away from Earth. These are particularly useful since they tend to very little baryonic matter. The spectrum and intensity of a gamma ray signal depends on the annihilation products, Another type of indirect WIMP signal could come from the Sun
29.
COUPP
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PICO is an experiment searching for direct evidence of dark matter using a bubble detector of chlorofluorocarbon as the active mass. It is located at SNOLAB in Canada and it was formed in 2013 from the merger of two similar experiments, PICASSO and COUPP. PICASSO is predominantly sensitive to spin-dependent interactions of Weakly Interacting Massive Particles with fluorine atoms, COUPP was a similar project with members from Fermilab, University of Chicago, and Indiana University. Prototypes were tested in the MINOS experiment far hall, with an experiment also operating at SNOLAB. It used trifluoroiodomethane (CF3I as the medium, a bubble detector is a radiation sensitive device that uses small droplets of superheated liquid that are suspended in a gel matrix. When enough energy is deposited in a droplet by ionizing radiation the superheated droplet undergoes a phase transition, the PICASSO detectors contain Freon droplets with an average diameter of 200 µm. The bubble development in the detector is accompanied by a shock wave that is picked up by piezo-electric sensors. The main advantage of the bubble detector technique is that the detector is almost insensitive to background radiation, the detector sensitivity can be adjusted by changing the temperature of the droplets. Freon-loaded detectors are typically operated at temperatures between 15–55 °C, the validity of the bubble detector concept has been shown in several publications. There is another experiment using this technique in Europe called SIMPLE. PICASSO reports results for spin-dependent WIMP interactions on 19F, no dark matter signal has been found, but for WIMP masses of 24 GeV/c2 new stringent limits have been obtained on the spin-dependent cross section for WIMP scattering on 19F of 13.9 pb. This result has been converted into a cross section limit for WIMP interactions on protons of 0.16 pb, the obtained limits restrict recent interpretations of the DAMA/LIBRA annual modulation effect in terms of spin dependent interactions. New results were published in May 2012, using 10 detectors with total exposure 14 kg·d, the best spin-dependent limits were obtained for a 20 GeV/c2 WIMP mass,0.032 pb for proton cross section. For the Spin-independent near 7 GeV low mass region cross section,1. 41×10−4 pb upper limit V. Zacek, PICO experiment website PICASSO experiment website COUPP experiment website
30.
SNOLAB
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SNOLAB is a Canadian underground physics laboratory at a depth of 2 km in Vales Creighton nickel mine in Sudbury, Ontario. The original Sudbury Neutrino Observatory experiment has ended, but the facilities have expanded into a permanent underground laboratory. Although accessed through a mine, the laboratory proper is maintained as a class-2000 cleanroom, with low levels of dust. The Sudbury Neutrino Observatory was the worlds deepest underground experiment since the Kolar Gold Fields experiments ended with the closing of that mine in 1992. With the deepest underground laboratory in North America at 2100 metre water equivalent depth, many other groups were interested in conducting experiments in the 6000 m. w. e. In 2002, funding was approved by the Canada Foundation for Innovation to expand the SNO facilities into a general-purpose laboratory, construction of the major laboratory space was completed in 2009, with the entire lab entering operation as a clean space in March 2011. SNOLAB was briefly the worlds deepest underground laboratory, until it was surpassed by the 2.4 km-deep China Jinping Underground Laboratory at the end of 2010, CJPL achieves a muon flux of less than 0.2 μ/m²/day, slightly less than SNOLABs 0.27 μ/m²/day. The planned DUSEL laboratory in the United States, which would have deeper, was greatly scaled back after the National Science Foundation refused major funding in 2010. Four more experiments are currently under construction, The SNO+ neutrino detector, MiniCLEAN dark matter detector, SuperCDMS dark matter detector, the DEAP-1 dark matter search, and The PICASSO dark matter search. There are also plans for a larger PICO-250L detector, the total size of the SNOLAB underground facilities, including utility spaces and personnel spaces, is, SNOLAB website SNOLAB french presentations Experiment Cave. Going deep underground in Canada in search of dark matter, redpath completes $65 million SNOLAB expansion
31.
Energy
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In physics, energy is the property that must be transferred to an object in order to perform work on – or to heat – the object, and can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton. Mass and energy are closely related, for example, with a sensitive enough scale, one could measure an increase in mass after heating an object. Living organisms require available energy to stay alive, such as the humans get from food. Civilisation gets the energy it needs from energy resources such as fuels, nuclear fuel. The processes of Earths climate and ecosystem are driven by the radiant energy Earth receives from the sun, the total energy of a system can be subdivided and classified in various ways. It may also be convenient to distinguish gravitational energy, thermal energy, several types of energy, electric energy. Many of these overlap, for instance, thermal energy usually consists partly of kinetic. Some types of energy are a mix of both potential and kinetic energy. An example is energy which is the sum of kinetic. Whenever physical scientists discover that a phenomenon appears to violate the law of energy conservation. Heat and work are special cases in that they are not properties of systems, in general we cannot measure how much heat or work are present in an object, but rather only how much energy is transferred among objects in certain ways during the occurrence of a given process. Heat and work are measured as positive or negative depending on which side of the transfer we view them from, the distinctions between different kinds of energy is not always clear-cut. In contrast to the definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness. The modern analog of this property, kinetic energy, differs from vis viva only by a factor of two, in 1807, Thomas Young was possibly the first to use the term energy instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described kinetic energy in 1829 in its modern sense, the law of conservation of energy was also first postulated in the early 19th century, and applies to any isolated system. It was argued for years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat and these developments led to the theory of conservation of energy, formalized largely by William Thomson as the field of thermodynamics
32.
Nobel Foundation
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The Nobel Foundation is a private institution founded on 29 June 1900 to manage the finances and administration of the Nobel Prizes. The Foundation is based on the last will of Alfred Nobel and it also holds Nobel Symposia on important breakthroughs in science and topics of cultural or social significance. Alfred Bernhard Nobel, born on 21 October 1833 in Stockholm Sweden, was a chemist, engineer, innovator, armaments manufacturer and he owned Bofors, a major armaments manufacturer, which he had redirected from its original business as an iron and steel mill. Nobel held 355 different patents, dynamite being the most famous, Nobel amassed a sizeable personal fortune during his lifetime, thanks mostly to this invention. In 1896 Nobel died of a stroke in his villa in San Remo, Nobels will expressed a request, to the surprise of many, that his money be used for prizes in physics, chemistry, peace, physiology or medicine and literature. Though Nobel wrote several wills during his lifetime, the last was written a little over a year before he died, Nobel bequeathed 94% of his total assets,31 million Swedish kronor, to establish and endow the five Nobel Prizes. The executors of his will were Ragnar Sohlman and Rudolf Lilljequist who formed the Nobel Foundation to take care of Nobels fortune, as of December 31,2015, the assets controlled by the Nobel Foundation amounted to 4.065 billion Swedish kronor. The Nobel Foundation was founded as an organisation on 29 June 1900 specifically to manage the finances. It is based on Nobels last will and testament, at the time Nobels will led to much specticism and criticism and thus it was not until April 26,1897 that his will was approved by the Storting. Soon thereafter they appointed the members of the Norwegian Nobel Committee that was to award the Peace Prize, shortly after, the other prize-awarding organizations followed, Karolinska Institutet on June 7, the Swedish Academy on June 9 and the Royal Swedish Academy of Sciences on June 11. The next thing the Nobel Foundation did was to try to agree on guidelines for how the Nobel Prize should be awarded, in 1900 the Nobel Foundations newly created statutes were promulgated by King Oscar II. In 1905 the Union between Sweden and Norway was dissolved which meant the responsibility for awarding Nobel Prizes was split between the two countries, norways Nobel Committee became the awarder of the Peace Prize while Sweden became the awarder of the other prizes. In accordance with Nobels will, the task of the Nobel Foundation is to manage the fortune Nobel left after him in a fund. Another important task of the Nobel Foundation is to represent the Nobel Prize to the outside world, the Nobel Foundation is not involved in any way in the process of selecting the Nobel laureates. In many ways the Nobel Foundation is similar to an investment company in that it invests money in ways to create a solid funding base for the prize. The Nobel Foundation is exempt from all taxes in Sweden and from investment taxes in the United States, since the 1980s the Foundations investments began to earn more money than previously. At the beginning of the 1980s the award money was 1 million SEK, according to the statutes the Foundation should consist of a Board with its seat in Stockholm. It should consist of five men, the Chairman of the board should be appointed by the King in Council
33.
Lawrence Berkeley National Laboratory
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It is managed and operated by the University of California. The laboratory overlooks the University of California, Berkeleys main campus, the laboratory was founded in August 26,1931 by Ernest Lawrence as the Radiation Laboratory of the University of California, Berkeley associated with the Physics Department. It centered physics research around his new instrument, the cyclotron, throughout the 1930s, Lawrence pushed to create larger and larger machines for physics research, courting private philanthropists for funding. The lab moved to its site atop the hill above campus in 1940 as its machines, specifically the 184-inch cyclotron, lawrences lab helped contribute to what has been judged to be the three most valuable technology developments of the war. The cyclotron was finished in November 1946, the Manhattan Project shut down two months later, after the war, Lawrence maintained strong government and military ties at his lab, which became incorporated into the new system of Atomic Energy Commission National Laboratories. For security purposes, classified weapons research was assigned to the isolated locations, the Los Alamos National Laboratory in New Mexico. Livermore, about an hours drive southeast of Berkeley, was established at a naval air station in 1952 by Lawrence. Weapons-related and collaborative research continued at Berkeley Lab until the 1970s, shortly after the death of Lawrence in August 1958, the UC Radiation Laboratory was renamed the Lawrence Radiation Laboratory. The Berkeley location became the Lawrence Berkeley Laboratory in 1971, although continued to call it the Rad Lab. Gradually, another shortened form came into common usage, LBL and its formal name was amended to Ernest Orlando Lawrence Berkeley National Laboratory in 1995, when National was added to the names of all DOE labs. Ernest Orlando was later dropped to shorten the name, today, the lab is commonly referred to as Berkeley Lab. Over 1700 memos are available on-line, hosted by the Laboratory and it was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab tradition that continues today, about 2,500 scientist-users carry out research at ALS every year. Berkeley Lab is proposing an upgrade of ALS which would increase the coherent flux of soft x-rays by two-three orders of magnitude, the Joint Genome Institute supports genomic research in support of the DOE missions in alternative energy, glocal carbon cycling, and environmental management. The JGIs partner laboratories are Berkeley Lab, Lawrence Livermore National Lab, Oak Ridge National Laboratory, Pacific Northwest National Laboratory, approximately 1,200 scientist-users take advantage of JGIs capabilities for their research every year. The Molecular Foundry is a multidisciplinary nanoscience research facility that provides users access to cutting-edge instrumentation. Approximately 700 scientist-users make use of facilities in their research every year. The National Energy Research Scientific Computing Center is the computing facility that provides large-scale state-of-the-art computing for the DOEs unclassified research programs
34.
CERN
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The European Organization for Nuclear Research, known as CERN, is a European research organization that operates the largest particle physics laboratory in the world. Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border, Israel is the only non-European country granted full membership. The main site at Meyrin hosts a large computing facility, which is used to store and analyse data from experiments. Researchers need remote access to facilities, so the lab has historically been a major wide area network hub. CERN is also the birthplace of the World Wide Web, the convention establishing CERN was ratified on 29 September 1954 by 12 countries in Western Europe. The acronym was retained for the new laboratory after the council was dissolved. CERNs first president was Sir Benjamin Lockspeiser, edoardo Amaldi was the general secretary of CERN at its early stages when operations were still provisional, while the first Director-General was Felix Bloch. The laboratory was originally devoted to the study of atomic nuclei, therefore, the laboratory operated by CERN is commonly referred to as the European laboratory for particle physics, which better describes the research being performed there. Several important achievements in physics have been made through experiments at CERN. The 1984 Nobel Prize for Physics was awarded to Carlo Rubbia, the 1992 Nobel Prize for Physics was awarded to CERN staff researcher Georges Charpak for his invention and development of particle detectors, in particular the multiwire proportional chamber. The World Wide Web began as a CERN project named ENQUIRE, initiated by Tim Berners-Lee in 1989, Berners-Lee and Cailliau were jointly honoured by the Association for Computing Machinery in 1995 for their contributions to the development of the World Wide Web. Based on the concept of hypertext, the project was intended to facilitate the sharing of information between researchers, the first website was activated in 1991. On 30 April 1993, CERN announced that the World Wide Web would be free to anyone, a copy of the original first webpage, created by Berners-Lee, is still published on the World Wide Web Consortiums website as a historical document. Prior to the Webs development, CERN had pioneered the introduction of Internet technology, a short history of this period can be found at CERN. ch. More recently, CERN has become a facility for the development of computing, hosting projects including the Enabling Grids for E-sciencE. It also hosts the CERN Internet Exchange Point, one of the two main internet exchange points in Switzerland. 48×10−5, a measurement with 6. 0-sigma significance. However, on 23 February, CERN stated in a release that the results were flawed due to an incorrectly connected GPS-synchronization cable. In March 2012, the ICARUS Collaboration reported that the measurement would be reproduced by both OPERA and ICARUS, further tests, after fixing the GPS connector, showed speed measurements consistent with the speed of light from four experiments at Gran Sasso, including OPERA
35.
Sensor
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A sensor is always used with other electronics, whether as simple as a light or as complex as a computer. Moreover, analog sensors such as potentiometers and force-sensing resistors are still widely used, applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robotics and many other aspects of our day-to-day life. A sensors sensitivity indicates how much the output changes when the input quantity being measured changes. For instance, if the mercury in a thermometer moves 1 cm when the changes by 1 °C. Some sensors can also affect what they measure, for instance, Sensors are usually designed to have a small effect on what is measured, making the sensor smaller often improves this and may introduce other advantages. Technological progress allows more and more sensors to be manufactured on a scale as microsensors using MEMS technology. In most cases, a microsensor reaches a higher speed. Most sensors have a transfer function. The sensitivity is defined as the ratio between the output signal and measured property. For example, if a sensor measures temperature and has a voltage output, the sensitivity is the slope of the transfer function. Converting the sensors electrical output to the measured units requires dividing the output by the slope. In addition, an offset is added or subtracted. For example -40 must be added to the output if 0 V output corresponds to -40 C input, for an analog sensor signal to be processed, or used in digital equipment, it needs to be converted to a digital signal, using an analog-to-digital converter. The full scale range defines the maximum and minimum values of the measured property, the sensitivity may in practice differ from the value specified. This is called a sensitivity error and this is an error in the slope of a linear transfer function. If the output differs from the correct value by a constant. This is an error in the y-intercept of a transfer function. Nonlinearity is deviation of a transfer function from a straight line transfer function
36.
Geophone
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A geophone is a device that converts ground movement into voltage, which may be recorded at a recording station. The deviation of this voltage from the base line is called the seismic response and is analyzed for structure of the earth. The term geophone derives from the Greek word γῆ meaning earth, geophones have historically been passive analog devices and typically comprise a spring-mounted magnetic mass moving within a wire coil to generate an electrical signal. The response of a geophone is proportional to ground velocity. MEMS have a higher noise level than geophones and can only be used in strong motion or active seismic applications. The frequency response of a geophone is that of an oscillator, fully determined by corner frequency. Since the corner frequency is proportional to the root of the moving mass. It is possible to lower the corner electronically, at the price of higher noise. Although waves passing through the earth have a nature, geophones are normally constrained to respond to single dimension - usually the vertical. However, some require the full wave to be used. In analog devices, three moving coil elements are mounted in an arrangement within a single case. The majority of geophones are used in seismology to record the energy waves reflected by the subsurface geology. In this case the primary interest is in the motion of the Earths surface. However, not all the waves are upwards travelling, a strong, horizontally transmitted wave known as ground-roll also generates vertical motion that can obliterate the weaker vertical signals. By using large areal arrays tuned to the wavelength of the ground-roll the dominant noise signals can be attenuated, analog geophones are very sensitive devices which can respond to very distant tremors. These small signals can be drowned by larger signals from local sources and it is possible though to recover the small signals caused by large but distant events by correlating signals from several geophones deployed in an array. Signals which are registered only at one or few geophones can be attributed to unwanted, local events and it can be assumed that small signals that register uniformly at all geophones in an array can be attributed to a distant and therefore significant event. The sensitivity of passive geophones is typically 30 Volts/, so they are in general not a replacement for broadband seismometers, conversely, some applications of geophones are interested only in very local events
37.
Hydrophone
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A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates electricity when subjected to a pressure change, such piezoelectric materials, or transducers, can convert a sound signal into an electrical signal since sound is a pressure wave. Some transducers can also serve as a projector, but not all have this capability, a hydrophone can listen to sound in air but will be less sensitive due to its design as having a good acoustic impedance match to water, which is a denser fluid than air. The earliest widely used design was the Fessenden oscillator, an electrodynamically driven clamped-edge circular plate transducer operating at 500,1000, ernest Rutherford, in England, led pioneer research in hydrophones using piezoelectric devices, and his only patent was for a hydrophone device. The acoustic impedance of piezoelectric materials facilitated their use as underwater transducers, the piezoelectric hydrophone was used late in World War I, by convoy escorts detecting U-boats, greatly impacting the effectiveness of submarines. From late in World War I until the introduction of active sonar, hydrophones were the method for submarines to detect targets while submerged. A small single cylindrical ceramic transducer can achieve near perfect omnidirectional reception and this type of hydrophone can be produced from a low-cost omnidirectional type, but must be used while stationary, as the reflector impedes its movement through water. A new way to direct is to use a body around the hydrophone. The array may be steered using a beamformer, most commonly, hydrophones are arranged in a line array but may be in two- or three-dimensional arrangements. These are capable of clearly recording extremely low frequency infrasound, including many unexplained ocean sounds, communication with submarines Underwater acoustics Sonar Reflection seismology Pike, John. How to build & use low-cost hydrophones, dOSITS—Hydrophone introduction at Discovery of Sound in the Sea orcasound. High Quality Hydrophones— High quality manufacturer of Hydrophones
38.
Microphone
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A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal. Several different types of microphone are in use, which employ different methods to convert the air pressure variations of a wave to an electrical signal. Microphones typically need to be connected to a preamplifier before the signal can be recorded or reproduced, in order to speak to larger groups of people, a need arose to increase the volume of the human voice. The earliest devices used to achieve this were acoustic megaphones, some of the first examples, from fifth century BC Greece, were theater masks with horn-shaped mouth openings that acoustically amplified the voice of actors in amphitheatres. In 1665, the English physicist Robert Hooke was the first to experiment with an other than air with the invention of the lovers telephone made of stretched wire with a cup attached at each end. German inventor Johann Philipp Reis designed an early sound transmitter that used a strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved with the transmitter design in Scottish-American Alexander Graham Bells telephone of 1876 – the diaphragm was attached to a conductive rod in an acid solution. These systems, however, gave a poor sound quality. The first microphone that enabled proper voice telephony was the carbon microphone and this was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, the carbon microphone is the direct prototype of todays microphones and was critical in the development of telephony, broadcasting and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886 and this microphone was employed at the first ever radio broadcast, a performance at the New York Metropolitan Opera House in 1910. In 1916, E. C. Wente of Western Electric developed the next breakthrough with the first condenser microphone, in 1923, the first practical moving coil microphone was built. The Marconi Skykes or magnetophon, developed by Captain H. J. Round, was the standard for BBC studios in London and this was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day. Also in 1923, the microphone was introduced, another electromagnetic type, believed to have been developed by Harry F. Olson. Over the years these microphones were developed by companies, most notably RCA that made large advancements in pattern control. With television and film technology booming there was demand for high fidelity microphones, electro-Voice responded with their Academy Award-winning shotgun microphone in 1963. During the second half of 20th century development advanced quickly with the Shure Brothers bringing out the SM58, digital was pioneered by Milab in 1999 with the DM-1001. The latest research developments include the use of optics, lasers and interferometers
39.
Seismometer
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Seismometers are instruments that measure motion of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources. Records of seismic waves allow seismologists to map the interior of the Earth, the seismometer was invented by the Chinese polymath Zhang Heng in AD132 during the Han dynasty. The first Western description of a comes from the French physicist and priest Jean de Hautefeuille in 1703. The modern seismometer was developed in the 19th century by John Milne, James Alfred Ewing, seismograph is another Greek term from seismós and γράφω, gráphō, to draw. The concerning technical discipline is called seismometry, a branch of seismology, a simple seismometer that is sensitive to up-down motions of the earth can be understood by visualizing a weight hanging on a spring. The spring and weight are suspended from a frame that moves along with the earthʼs surface, as the earth moves, the relative motion between the weight and the earth provides a measure of the vertical ground motion. Any movement of the moves the frame. The mass tends not to move because of its inertia, early seismometers used optical levers or mechanical linkages to amplify the small motions involved, recording on soot-covered paper or photographic paper. In some systems, the mass is held nearly motionless relative to the frame by a negative feedback loop. The motion of the relative to the frame is measured. The voltage needed to produce this force is the output of the seismometer, in other systems the weight is allowed to move, and its motion produces a voltage in a coil attached to the mass and moving through the magnetic field of a magnet attached to the frame. This design is used in the geophones used in seismic surveys for oil. Professional seismic observatories usually have instruments measuring three axes, north-south, east-west, and the vertical, if only one axis is measured, this is usually the vertical because it is less noisy and gives better records of some seismic waves. The foundation of a station is critical. A professional station is mounted on bedrock. The best mountings may be in deep boreholes, which avoid thermal effects, ground noise and tilting from weather, other instruments are often mounted in insulated enclosures on small buried piers of unreinforced concrete. Reinforcing rods and aggregates would distort the pier as the temperature changes, a site is always surveyed for ground noise with a temporary installation before pouring the pier and laying conduit. Originally, European seismographs were placed in an area after a destructive earthquake
40.
Blind spot monitor
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The blind spot monitor is a vehicle-based sensor device that detects other vehicles located to the driver’s side and rear. Warnings can be visual, audible, vibrating, or tactile, however, blind spot monitors are an option that may do more than monitor the sides and rear of the vehicle. They may also include Cross Traffic Alert, which alerts drivers backing out of a parking space when traffic is approaching from the sides, if side view mirrors are properly adjusted on a car, there is no blind spot on the sides. Platzer received a patent for his blind spot monitor, and it has incorporated into various products associated with Ford Motor Company. The blind zone mirror has been touted as an elegant and relatively inexpensive solution to this recognized problem, Volvo BLIS is an acronym for Blind Spot Information System, a system of protection developed by Volvo. Volvos previous parent, Ford Motor Company, has adapted the system to its Ford, Lincoln. Mazda Mazda was the first Japanese automaker to offer a blind spot monitor and it was initially introduced on the 2008 Mazda CX-9 Grand Touring and remained limited to only that highest trim level through the 2012 model year. For 2013, BSM was standard on both the CX-9 Touring and Grand Touring models, Mazda also added BSM to the redesigned 2009 Mazda 6. Blind spot monitoring was standard equipment on the 6i and 6s Grand Touring trim levels, and was an available option on some lower trim levels. Mazda has since expanded the availability of BSM, having added it to the feature list of the Mazda3, CX-5, MX-5 Miata, Ford Ford uses the acronym BLIS for its blind spot detection. The system is both in drive and neutral transmission gears, and is turned off when in reverse or park gears. On Ford products, the system was first introduced in the spring of 2009, on the 2010 Ford Fusion and Fusion Hybrid,2010 Mercury Milan and Milan Hybrid, Mitsubishi Mitsubishi offers a Blind Spot Warning on the Pajero Sport launched in 2016. Toyota Toyota Motors Safety Sense package, which includes Blind Spot Monitoring, among other features, is standard equipment in multiple models sold in the U. S, in 2010, the Nissan Fuga/Infiniti M for the first time offered counter steering capabilities to keep the vehicle from colliding. Those capabilities have been adopted by competitors, such as Toyota, youTube Ford How-to video, BLIS with Cross-Traffic Alert Google patent search of Blind spot monitoring system The danger of blind zones The area behind your vehicle can be a killing zone
41.
Crankshaft position sensor
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A crank sensor is an electronic device used in an internal combustion engine, both petrol and diesel, to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control the fuel injection or the ignition system timing, before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on petrol engines. This method is used to synchronise a four stroke engine upon starting, allowing the management system to know when to inject the fuel. It is also used as the primary source for the measurement of engine speed in revolutions per minute. Common mounting locations include the main crank pulley, the flywheel and this sensor is the 2nd most important sensor in modern-day engines after the camshaft position sensor. When it fails, there is a probability the engine will not start, there are three main types of sensor commonly in use. The Hall Effect sensor, Optical sensor or the Inductive sensor, some engines, such as GMs Premium V family, use crank position sensors which read a reluctor ring integral to the harmonic balancer. This is a more accurate method of determining the position of the crankshaft. The functional objective for the position sensor is to determine the position and/or rotational speed of the crank. Engine Control Units use the information transmitted by the sensor to control such as ignition timing. In a diesel the sensor will control the fuel injection, the sensor output may also be related to other sensor data including the cam position to derive the current combustion cycle, this is very important for the starting of a four stroke engine. Sometimes, the sensor may become burnt or worn out - or just die of old age at high mileage, one likely cause of crankshaft position sensor failure is exposure to extreme heat. Others are vibration causing a wire to fracture or corrosion on the pins of harness connectors, many modern crankshaft sensors are sealed units and therefore will not be damaged by water or other fluids. When it goes wrong, it stops transmitting the signal contains the vital data for the ignition. A bad crank position sensor can worsen the way the engine idles, if the engine is revved up with a bad or faulty sensor, it may cause misfiring, motor vibration or backfires. Acceleration might be hesitant, and abnormal shaking during engine idle might occur, in the worst case the car may not start. The first sign of crankshaft failure, usually, is the refusal of the engine to start when hot. Another type of sensor is used on bicycles to monitor the position of the crankset
42.
Curb feeler
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Curb feelers or curb finders are springs or wires installed on a vehicle which act as whiskers to alert drivers when they are at the right distance from the curb while parking. The devices are fitted low on the body, close to the wheels, as the vehicle approaches the curb, the protruding feelers scrape against the curb, making a noise and alerting the driver in time to avoid damaging the wheels or hubcaps. The feelers are manufactured to be flexible and do not easily break, curb feelers are still used on some hot rods when a 1950s look is wanted. They are especially popular for cars with tires, which easily lose their white coating when scraped against the curb. Sometimes curb feelers are found only on the side of the car. Sometimes they are added next to the front wheels. Some curb feelers have a wire or spring, while others have two to increase the area that can be protected. Any particular car may have just one curb feeler installed or more if attached near the front and rear, as well as on both sides of the vehicle. Buses are sometimes fitted with curb feelers, which can assist the driver in ensuring that the bus is close enough to the curb to allow passengers to step to and from the curb easily. This will give a warning nudge to anyone in the danger area, the belting is stiff enough to hold its shape but flexible enough to give if it runs into a miner or vice versa. The flexibility also allows this curb feeler to drag against the rib or be smacked by a car with little or no damage. A little spray from a can of paint will make the belt a visual warning device as well. One or two on each corner will help or put as many as you want, curb feelers based on optical technology are designed to function the same way but work in the proximity of an obstruction rather than having to come into physical contact with it. As described by one United States patent, An electronic curb feeler system uses two pairs of optical sensor units to detect an object located near the front end of a vehicle during parking. Devices such as this, and simpler electronic devices similar to the original wire curb feelers used on cars, are used in the design of various mobile robotic devices, one robotics company that does work for the United States Department of Defense uses laser-assisted curb feeler technology
