|
Breit–Wheeler Process
The Breit–Wheeler process or Breit–Wheeler pair production is a proposed physical process in which a positron–electron pair is created from the collision of two photons. It is the simplest mechanism by which pure light can be potentially transformed into matter. The process can take the form γ γ′ → e+ e− where γ and γ′ are two light quanta (for example, gamma ray, gamma photons). The multiphoton Breit–Wheeler process, also referred to as nonlinear Breit–Wheeler or strong field Breit–Wheeler in the literature, occurs when a high-energy probe photon decays into pairs propagating through a strong electromagnetic field (for example, a laser pulse). In contrast with the linear process, this can take the form of γ + n ω → e+ e−, where n represents the number of photons, and ω represents the coherent laser field. The inverse process, e+ e− → γ γ′, in which an electron and a positron collide and annihilate to generate a pair of gamma photons, is kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breit Wheeler Process
Breit () is an ''Ortsgemeinde'' – a Municipalities of Germany, municipality belonging to a ''Verbandsgemeinde'', a kind of collective municipality – in the Bernkastel-Wittlich Districts of Germany, district in Rhineland-Palatinate, Germany. Geography The municipality lies in the Hunsrück on a knoll about 400 m above sea level and thereby some 150 m above the bottom of the Kleine Dhron river valley. Breit belongs to the Thalfang am Erbeskopf, ''Verbandsgemeinde'' of Thalfang am Erbeskopf, whose seat is in the municipality of Thalfang. History In the early 13th century, Breit had its first documentary mention in the name “Conrad von Breit” in a record from St. Maximin's Abbey, Trier, St. Maximin’s Abbey. After the French Revolution, the Rhine’s left bank, and along with it Breit, were ceded to France in 1794 and 1795. Through a law from 26 March 1798, the French abolished Feudalism, feudal rights in their zone of occupation. After French rule ended, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gregory Breit
Gregory Breit (, ; July 14, 1899 – September 13, 1981) was an American physicist born in Mykolaiv, Russian Empire (now Mykolaiv, Ukraine). He was a professor at New York University (1929–1934), University of Wisconsin–Madison (1934–1947), Yale University (1947–1968), and University at Buffalo (1968–1973). In 1921, he was Paul Ehrenfest's assistant in Leiden University. Biography He was born in the city of Mykolaiv in the family of the book publisher Alfred Schneider. After the death of his mother in 1911, his father left for the United States of America. Until 1915, Gregory studied at the Mykolaiv Oleksandrivska gymnasium. In 1915, he followed his father to USA. He studied at Johns Hopkins University: in 1918 he obtained a Bachelor degree, in 1920 a Master degree, and in 1921 he earned a PhD in physics. In 1921-1922, he worked as a researcher at Leiden University. In 1922-1923, he was a research fellow at Harvard University. From 1923 to 1924, he was an assistant p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodymium
Neodymium is a chemical element; it has Symbol (chemistry), symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth element, rare-earth metals. It is a hard (physics), hard, slightly malleable, silvery metal that quickly tarnishes in air and moisture. When oxidized, neodymium reacts quickly producing pink, purple/blue and yellow compounds in the +2, +3 and +4 oxidation states. It is generally regarded as having one of the most complex emission spectrum, spectra of the elements. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach, who also discovered praseodymium. Neodymium is present in significant quantities in the minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is Abundance of elements in Eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ars Technica
''Ars Technica'' is a website covering news and opinions in technology, science, politics, and society, created by Ken Fisher and Jon Stokes in 1998. It publishes news, reviews, and guides on issues such as computer hardware and software, science, technology policy, and video games. ''Ars Technica'' was privately owned until May 2008, when it was sold to Condé Nast Digital, the online division of Condé Nast Publications. Condé Nast purchased the site, along with two others, for $25 million and added it to the company's ''Wired'' Digital group, which also includes '' Wired'' and, formerly, Reddit. The staff mostly works from home and has offices in Boston, Chicago, London, New York City, and San Francisco. The operations of ''Ars Technica'' are funded primarily by advertising, and it has offered a paid subscription service since 2001. History Ken Fisher, who serves as the website's current editor-in-chief, and Jon Stokes created ''Ars Technica'' in 1998. Its purpose was t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-linear Inverse Compton Scattering
Non-linear inverse Compton scattering (NICS), also known as non-linear Compton scattering and multiphoton Compton scattering, is the scattering of multiple low-energy photons, given by an intense electromagnetic field, in a high-energy photon (X-ray or gamma ray) during the interaction with a charged particle, in many cases an electron. This process is an inverted variant of Compton Scattering, Compton scattering since, contrary to it, the charged particle transfers its energy to the outgoing high-energy photon instead of receiving energy from an incoming high-energy photon. Furthermore, differently from Compton scattering, this process is explicitly non-linear because the conditions for multiphoton absorption by the charged particle are reached in the presence of a very intense electromagnetic field, for example, the one produced by high-intensity lasers. Non-linear inverse Compton scattering is a scattering process belonging to the category of light-matter interaction phenomena. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pair Production
Pair production is the creation of a subatomic particle and its antiparticle from a neutral boson. Examples include creating an electron and a positron, a muon and an antimuon, or a proton and an antiproton. Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created. (As the electron is the lightest, hence, lowest mass/energy, elementary particle, it requires the least energetic photons of all possible pair-production processes.) Conservation of energy and momentum are the principal constraints on the process. All other conserved quantum numbers ( angular momentum, electric charge, lepton number) of the produced particles must sum to zero thus the created particles shall have opposite values of each other. For instance, if one partic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronvolt
In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an Voltage, electric potential difference of one volt in vacuum. When used as a Units of energy, unit of energy, the numerical value of 1 eV in joules (symbol J) is equal to the numerical value of the Electric charge, charge of an electron in coulombs (symbol C). Under the 2019 revision of the SI, this sets 1 eV equal to the exact value Historically, the electronvolt was devised as a standard unit of measure through its usefulness in Particle accelerator#Electrostatic particle accelerators, electrostatic particle accelerator sciences, because a particle with electric charge ''q'' gains an energy after passing through a voltage of ''V''. Definition and use An electronvolt is the amount of energy gained or lost by a single electron when it moves through an Voltage, electric potential differenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nature Photonics
''Nature Photonics'' is a peer-reviewed scientific journal published by the Nature Publishing Group. The editor-in-chief is Oliver Graydon. The journal covers research related to optoelectronics, laser science, imaging, communications, and other aspects of photonics and was established in January 2007. ''Nature Photonics'' publishes review articles, research papers, News and Views pieces, and research highlights summarizing the latest scientific findings in optoelectronics. This is complemented by a mix of articles dedicated to the business side of the industry covering areas such as technology commercialization and market analysis. The papers that have been published in this journal are internationally acclaimed for maintaining high research standards. The journal is regarded as top-ranking in the field of photonics. ''Nature Photonics'' is indexed in the NASA Astrophysics Data System and Science Citation Index The Science Citation Index Expanded (SCIE) is a citation index owne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monte Carlo Simulation
Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be deterministic in principle. The name comes from the Monte Carlo Casino in Monaco, where the primary developer of the method, mathematician Stanisław Ulam, was inspired by his uncle's gambling habits. Monte Carlo methods are mainly used in three distinct problem classes: optimization, numerical integration, and generating draws from a probability distribution. They can also be used to model phenomena with significant uncertainty in inputs, such as calculating the risk of a nuclear power plant failure. Monte Carlo methods are often implemented using computer simulations, and they can provide approximate solutions to problems that are otherwise intractable or too complex to analyze mathematically. Monte Carlo methods are widely used in various ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hohlraum
In radiation thermodynamics, a hohlraum (; a non-specific German word for a "hollow space", "empty room", or "cavity") is a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity. First proposed by Gustav Kirchhoff in 1860 and used in the study of black-body radiation (''hohlraumstrahlung''), this idealized cavity can be approximated in practice by a hollow container of any opaque material. The radiation escaping through a small perforation in the wall of such a container will be a good approximation of black-body radiation at the temperature of the interior of the container. Indeed, a hohlraum can even be constructed from cardboard, as shown by Purcell's Black Body Box, a hohlraum demonstrator. In spectroscopy, the Hohlraum effect occurs when an object achieves thermodynamic equilibrium with an enclosing hohlraum. As a consequence of Kirchhoff’s law, everything optically blends together and contrast between the walls and the object effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed Of Light
The speed of light in vacuum, commonly denoted , is a universal physical constant exactly equal to ). It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time interval of second. The speed of light is invariant (physics), the same for all observers, no matter their relative velocity. It is the upper limit for the speed at which Information#Physics_and_determinacy, information, matter, or energy can travel through Space#Relativity, space. All forms of electromagnetic radiation, including visible light, travel at the speed of light. For many practical purposes, light and other electromagnetic waves will appear to propagate instantaneously, but for long distances and sensitive measurements, their finite speed has noticeable effects. Much starlight viewed on Earth is from the distant past, allowing humans to study the history of the universe by viewing distant objects. When Data communication, comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperial College London
Imperial College London, also known as Imperial, is a Public university, public research university in London, England. Its history began with Prince Albert of Saxe-Coburg and Gotha, Prince Albert, husband of Queen Victoria, who envisioned a Albertopolis, cultural district in South Kensington that included museums, colleges, and the Royal Albert Hall. In 1907, these colleges – the Royal College of Science, the Royal School of Mines, and the City and Guilds of London Institute – merged to form the Imperial College of Science and Technology. In 1988, Imperial merged with St Mary's Hospital, London, St Mary's Hospital Medical School and then with Charing Cross and Westminster Medical School to form the Imperial College School of Medicine. The Imperial Business School was established in 2003 and officially opened by Elizabeth II, Queen Elizabeth II. Formerly a constituent college of the University of London, Imperial became an independent university in 2007. Imperial is o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
