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Molière Radius
The Molière radius is a characteristic constant of a material giving the scale of the transverse dimension of the fully contained Particle shower, electromagnetic showers initiated by an incident high energy electron or photon. By definition, it is the radius of a cylinder containing on average 90% of the shower's energy deposition. Two Molière radii contain 95% of the shower's energy deposition. It is related to the radiation length by the approximate relation , where is the atomic number. The Molière radius is useful in experimental particle physics in the design of calorimeter (particle physics), calorimeters: a smaller Molière radius means better shower position resolution, and better shower separation due to a smaller degree of shower overlaps. The Molière radius is named after German physicist Gert Molière, Paul Friederich Gaspard Gert Molière (1909–64).Phillip R. Sloan, Brandon Fogel, "Creating a Physical Biology: The Three-Man Paper and Early Molecular Biology" U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Shower
In particle physics, a shower is a cascade of secondary particles produced as the result of a high-energy particle interacting with dense matter. The incoming particle interacts, producing multiple new particles with lesser energy; each of these then interacts, in the same way, a process that continues until many thousands, millions, or even billions of low-energy particles are produced. These are then stopped in the matter and absorbed. Types There are two basic types of showers. ''Electromagnetic showers'' are produced by a particle that interacts primarily or exclusively via the electromagnetic force, usually a photon or electron. ''Hadronic showers'' are produced by hadrons (i.e. nucleons and other particles made of quarks), and proceed mostly via the strong nuclear force. Electromagnetic showers An electromagnetic shower begins when a high-energy electron, positron or photon enters a material. At high energies (above a few MeV), in which the photoelectric effect and C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stolzite
Stolzite is a mineral, a lead tungstate; with the chemical formula, formula Pbtungsten, Woxygen, O4. It is similar to, and often associated with, wulfenite which is the same chemical formula except that the tungsten is replaced by molybdenum. Stolzite crystallizes in the tetragonal crystal system and is Polymorphism (materials science), dimorphous with the monoclinic form raspite. Lead tungstate crystals have the optical transparency of glass combined with much higher density (8.28 g/cm3 vs ~2.2 g/cm3 for Fused quartz, fused silica). They are used as scintillators in particle physics because of their short radiation length (0.89 cm), low Molière radius (2.2 cm), quick scintillation response, and radiation hardness. Lead tungstate crystals are used in the Compact Muon Solenoid, Compact Muon Solenoid's electromagnetic calorimeter. It was first described in 1820 by August Breithaupt, who called it Scheelbleispath and then by François Sulpice Beudant in 1832, who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annual Review Of Nuclear Science , in biology
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Annual may refer to: *Annual publication, periodical publications appearing regularly once per year **Yearbook **Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), a musical group *Annual, every once in a while See also * Annual Review (other) * Circannual cycle In chronobiology, the circannual cycle is characterized by biological processes and behaviors recurring on an approximate annual basis, spanning a period of about one year. This term is particularly relevant in the analysis of seasonal environment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argon
Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), 23 times as abundant as carbon dioxide (400 ppmv), and more than 500 times as abundant as neon (18 ppmv). Argon is the most abundant noble gas in Earth's crust, comprising 0.00015% of the crust. Nearly all argon in Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas. The name "argon" is derived from the Greek word , neuter singular form of meaning 'lazy' or 'inactive', as a reference to the fact that the element undergoes almost no chemical reactions. The complete oc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krypton
Krypton (from 'the hidden one') is a chemical element; it has symbol (chemistry), symbol Kr and atomic number 36. It is a colorless, odorless noble gas that occurs in trace element, trace amounts in the Earth's atmosphere, atmosphere and is often used with other rare gases in fluorescent lamps. Krypton is chemically inert. Krypton, like the other noble gases, is used in lighting and photography. Krypton light has many spectral lines, and krypton Plasma (physics), plasma is useful in bright, high-powered gas lasers (krypton ion laser, ion and excimer laser, excimer lasers), each of which resonates and amplifies a single spectral line. krypton fluoride laser, Krypton fluoride also makes a useful laser medium. From 1960 to 1983, the history of the metre#Krypton standard, official definition of the metre was based on the wavelength of one spectral line of krypton-86, because of the high power and relative ease of operation of krypton discharge tubes. History Krypton was discovere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caesium Iodide
Caesium iodide or cesium iodide (chemical formula CsI) is the ionic compound of caesium and iodine. It is often used as the input phosphor of an X-ray image intensifier tube found in fluoroscopy equipment. Caesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths. Synthesis and structure Bulk caesium iodide crystals have the cubic CsCl crystal structure, but the structure type of nanometer-thin CsI films depends on the substrate material – it is CsCl for mica and NaCl for LiF, NaBr and NaCl substrates. Caesium iodide atomic chains can be grown inside double-wall carbon nanotubes. In such chains I atoms appear brighter than Cs atoms in electron micrographs despite having a smaller mass. This difference was explained by the charge difference between Cs atoms (positive), inner nanotube walls (negative) and I atoms (negative). As a result, Cs atoms are attracted to the walls and vibrate more strongly than I atoms, which are pushed toward the nanotube a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CERN
The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Geneva, on the France–Switzerland border. It comprises #Member states and budget, 24 member states. Israel, admitted in 2013, is the only full member geographically out of Europe. CERN is an official United Nations General Assembly observers#Intergovernmental organizations, United Nations General Assembly observer. The acronym CERN is also used to refer to the laboratory; in 2023, it had 2,666 scientific, technical, and administrative staff members, and hosted about 12,370 users from institutions in more than 80 countries. In 2016, CERN generated 49 Byte#Multiple-byte units, petabytes of data. CERN's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – consequently, numer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compact Muon Solenoid
The Compact Muon Solenoid (CMS) experiment is one of two large general-purpose particle physics detectors built on the Large Hadron Collider (LHC) at CERN in Switzerland and France. The goal of the CMS experiment is to investigate a wide range of physics, including the search for the Higgs boson, extra dimensions, and particles that could make up dark matter. CMS is 21 metres long, 15 m in diameter, and weighs about 14,000 tonnes. Over 4,000 people, representing 206 scientific institutes and 47 countries, form the CMS collaboration who built and now operate the detector. It is located in a cavern at Cessy in France, just across the border from Geneva. In July 2012, along with ATLAS, CMS tentatively discovered the Higgs boson. By March 2013 its existence was confirmed. Background Recent collider experiments such as the now-dismantled Large Electron-Positron Collider and the newly renovated Large Hadron Collider (LHC) at CERN, as well as the () recently clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetium–yttrium Oxyorthosilicate
Lutetium–yttrium oxyorthosilicate, also known as LYSO, is an inorganic chemical compound with main use as a scintillator crystal for gamma radiation detection. Its chemical formula is Lu2(1-x)Y2xSiO5. The percentage of yttrium varies considerably, with values in the literature ranging from 5% to 70%. It is commonly used to build screens and electromagnetic calorimeters in particle physics. LYSO crystals have the advantages of high light output and density, quick decay time, excellent energy resolution. The crystals are often grown in boules using the Czochralski process The Czochralski method, also Czochralski technique or Czochralski process, is a method of crystal growth used to obtain single crystals (monocrystals) of semiconductors (e.g. silicon, germanium and gallium arsenide), metals (e.g. palladium, plati ..., and cutting or polishing can be challenging because LYSO is brittle and hard. Intrinsic radiation in gamma spectroscopy LYSO scintillators contain naturally occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up quark, up and down quark, down quarks. Electrons are extremely lightweight particles that orbit the positively charged atomic nucleus, nucleus of atoms. Their negative charge is balanced by the positive charge of protons in the nucleus, giving atoms their overall electric charge#Charge neutrality, neutral charge. Ordinary matter is composed of atoms, each consisting of a positively charged nucleus surrounded by a number of orbiting electrons equal to the number of protons. The configuration and energy levels of these orbiting electrons determine the chemical properties of an atom. Electrons are bound to the nucleus to different degrees. The outermost or valence electron, valence electrons are the least tightly bound and are responsible for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gert Molière
Paul Friederich Gaspard Gert Molière (7 April 1909, Butzbach, Hessen – 1964, Tübingen) was a German theoretical physicist, specializing in nuclear physics and particle physics. He is known for the Molière radius, which is useful in studying Bhabha scattering. Education and career Gert Molière received in 1935 from the Humboldt University of Berlin his doctorate (Promotion) under the supervision of Max von Laue. In the same year Molière became a research assistant (and first theoretical physicist) at the Kaiser Wilhelm Institute (KWI) for physical chemistry and electrochemistry in Berlin-Dahlem (today's Fritz Haber Institute). At the institute he developed a quantum mechanical approach to X-ray scattering in extension of Laue's classical dynamic theory of diffraction. (At KWI, his younger brother Kurt Molière (1912–1994) completed his doctoral dissertation in 1939 on a related subject and after World War II headed a department.) After 1940, Gert Molière moved to the KW ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calorimeter (particle Physics)
In experimental particle physics, a calorimeter is a type of detector that measures the energy of subatomic particle, particles. Particles enter the calorimeter and initiate a particle shower in which their energy is deposited in the calorimeter, collected, and measured. The energy may be measured in its entirety, requiring total containment of the particle shower, or it may be sampled. Typically, calorimeters are segmented transversely to provide information about the direction of the particle or particles, as well as the energy deposited, and longitudinal segmentation can provide information about the identity of the particle based on the shape of the shower as it develops. Calorimetry design is an active area of research in particle physics. Types of calorimeters Electromagnetic versus hadronic such as electrons, positrons and photons. A . (See Particle shower#Types of showers, types of particle showers for the differences between the two.) Calorimeters are characterized b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
