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HERA-B
The HERA-B detector was a particle physics experiment at the HERA accelerator at the German national laboratory DESY that collected data from 1993 to 2003. It measured 8 m x 20 m x 9 m and weighed 1000 tons. The HERA-B collaboration consisted of some 250 scientists from 32 institutes in 13 countries. Its primary aim was to measure CP violation in the decays of heavy B mesons in the late 1990s, several years ahead of the Large Hadron Collider and B Factory programs. Unlike most particle physics detectors, the particles were produced not by colliding two circulating beams head-on, nor by slamming the beam into a stationary target, but by moving a thin wire target directly into the waste 'halo' of the circulating proton beam of the HERA accelerator. The beam was unaffected by this 'scraping' but the collision rate produced could be made extremely high, around 5 to 10 million interactions per second (5–10 MHz). The collaboration developed a novel scheme for moving the wires an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DESY
The Deutsches Elektronen-Synchrotron (English ''German Electron Synchrotron''), commonly referred to by the abbreviation DESY, is a national research center in Germany. It operates particle accelerators used to investigate the structure of matter, and conducts a broad spectrum of inter-disciplinary scientific research in three main areas: particle and high energy physics; photon science, and the development, construction and operation of particle accelerators. Its name refers to its first project, an electron synchrotron. DESY is publicly financed by the Federal Republic of Germany, the States of Germany, and the German Research Foundation (DFG). DESY is a member of the Helmholtz Association and operates at sites in Hamburg and Zeuthen. Functions DESY's function is to conduct fundamental research. It specializes in particle accelerator development, construction and operation, particle physics research to explore the fundamental characteristics of matter and forces, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B Factory
In particle physics, a B-factory, or sometimes a beauty factory, is a particle collider experiment designed to produce and detect a large number of B mesons so that their properties and behavior can be measured with small statistical uncertainty. Tau leptons and D mesons are also copiously produced at B-factories. History and development A sort of "prototype" or "precursor" B-factory was the HERA-B experiment at DESY that was planned to study B-meson physics in the 1990–2000s, before the actual B-factories were constructed/operational. However, usually HERA-B is not considered a B-factory. Two B-factories were designed and built in the 1990s, and they operated from late 1999 onward: the Belle experiment at the KEKB collider in Tsukuba, Japan, and the BaBar experiment at the PEP-II collider at SLAC in California, United States. They were both electron-positron colliders with the center of mass energy tuned to the ϒ(4S) resonance peak, which is just above the threshold f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and bosons (force-carrying particles). There are three generations of fermions, but ordinary matter is made only from the first fermion generation. The first generation consists of up and down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are electromagnetism, the weak interaction, and the strong interaction. Quarks cannot exist on their own but form hadrons. Hadrons that contain an odd number of quarks are called baryons and those that contain an even number are called mesons. Two baryons, the proton and the neutron, make up most of the mass of ordinary matter. Mesons are unstable and the longest-lived last for only a few hundredths of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HERA
In ancient Greek religion, Hera (; grc-gre, Ἥρα, Hḗrā; grc, Ἥρη, Hḗrē, label=none in Ionic and Homeric Greek) is the goddess of marriage, women and family, and the protector of women during childbirth. In Greek mythology, she is queen of the twelve Olympians and Mount Olympus, sister and wife of Zeus, and daughter of the Titans Cronus and Rhea. One of her defining characteristics in myth is her jealous and vengeful nature in dealing with any who offend her, especially Zeus' numerous adulterous lovers and illegitimate offspring. Her iconography usually presents her as a dignified, matronly figure, upright or enthroned, crowned with a ''polos'' or diadem, sometimes veiled as a married woman. She is the patron goddess of lawful marriage. She presides over weddings, blesses and legalises marital unions, and protects women from harm during childbirth. Her sacred animals include the cow, cuckoo and the peacock. She is sometimes shown holding a pomegranate, as an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
INSPIRE-HEP
INSPIRE-HEP is an open access digital library for the field of high energy physics (HEP). It is the successor of the Stanford Physics Information Retrieval System (SPIRES) database, the main literature database for high energy physics since the 1970s. History SPIRES was (in addition to the CERN Document Server (CDS), arXiv and parts of Astrophysics Data System) one of the main Particle Information Resources. A survey conducted in 2007 found that SPIRES database users wanted the portal to provide more services than the, at that time, already 30-year-old system could provide. On the second annual Summit of Information Specialists in Particle Physics and Astrophysics in May 2008, the physics laboratories CERN, DESY, SLAC and Fermilab therefore announced that they would work together to create a new Scientific Information System for high energy physics called INSPIRE. It interacts with other HEP service providers like arXiv.org, Particle Data Group, NASA's Astrophysics Data System. and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CP Violation
In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle (C-symmetry) while its spatial coordinates are inverted ("mirror" or P-symmetry). The discovery of CP violation in 1964 in the decays of neutral kaons resulted in the Nobel Prize in Physics in 1980 for its discoverers James Cronin and Val Fitch. It plays an important role both in the attempts of cosmology to explain the dominance of matter over antimatter in the present universe, and in the study of weak interactions in particle physics. Overview Until the 1950s, parity conservation was believed to be one of the fundamental geometric conservation laws (along with conservation of energy and conservation of momentum). After the discovery of parity violation in 1956, CP-symmetry was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B Meson
In particle physics, B mesons are mesons composed of a bottom antiquark and either an up (), down (), strange () or charm quark (). The combination of a bottom antiquark and a top quark is not thought to be possible because of the top quark's short lifetime. The combination of a bottom antiquark and a bottom quark is not a B meson, but rather ''bottomonium'', which is something else entirely. Each B meson has an antiparticle that is composed of a bottom quark and an up (), down (), strange () or charm () antiquark respectively. List of B mesons – oscillations The neutral B mesons, and , spontaneously transform into their own antiparticles and back. This phenomenon is called flavor oscillation. The existence of neutral B meson oscillations is a fundamental prediction of the Standard Model of particle physics. It has been measured in the – system to be about , and in the – system to be measured by CDF experiment at Fermilab. A first estimation of the lower an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Hadron Collider
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundreds of universities and laboratories, as well as more than 100 countries. It lies in a tunnel in circumference and as deep as beneath the France–Switzerland border near Geneva. The first collisions were achieved in 2010 at an energy of 3.5 teraelectronvolts (TeV) per beam, about four times the previous world record. After upgrades it reached 6.5 TeV per beam (13 TeV total collision energy). At the end of 2018, it was shut down for three years for further upgrades. The collider has four crossing points where the accelerated particles collide. Seven detectors, each designed to detect different phenomena, are positioned around the crossing points. The LHC primarily collides proton beams, but it can also accelerate beams of heavy ion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collider
A collider is a type of particle accelerator which brings two opposing particle beams together such that the particles collide. Colliders may either be ring accelerators or linear accelerators. Colliders are used as a research tool in particle physics by accelerating particles to very high kinetic energy and letting them impact other particles. Analysis of the byproducts of these collisions gives scientists good evidence of the structure of the subatomic world and the laws of nature governing it. These may become apparent only at high energies and for tiny periods of time, and therefore may be hard or impossible to study in other ways. Explanation In particle physics one gains knowledge about elementary particles by accelerating particles to very high kinetic energy and letting them impact on other particles. For sufficiently high energy, a reaction occurs that transforms the particles into other particles. Detecting these products gives insight into the physics involved. To do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one hertz is the reciprocal of one second. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon, via the Planck relation ''E'' = ''hν'', where ''E'' is the photon's energy, ''ν'' is its freq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Experiments
In the Outline of physical science, physical sciences, a particle (or corpuscule in older texts) is a small wikt:local, localized physical body, object which can be described by several physical property, physical or chemical property, chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from subatomic particles like the electron, to microscopic scale, microscopic particles like atoms and molecules, to macroscopic scale, macroscopic particles like powder (substance), powders and other granular materials. Particles can also be used to create scientific models of even larger objects depending on their density, such as humans moving in a crowd or celestial bodies in motion (physics), motion. The term ''particle'' is rather general in meaning, and is refined as needed by various scientific fields. Anything that is composed of particles may be referred to as being particulate. However, the noun ''particulates, particulate'' is most frequently ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B Physics
The bottom quark or b quark, also known as the beauty quark, is a third-generation heavy quark with a charge of − ''e''. All quarks are described in a similar way by electroweak and quantum chromodynamics, but the bottom quark has exceptionally low rates of transition to lower-mass quarks. The bottom quark is also notable because it is a product in almost all top quark decays, and is a frequent decay product of the Higgs boson. Name and history The bottom quark was first described theoretically in 1973 by physicists Makoto Kobayashi and Toshihide Maskawa to explain CP violation. The name "bottom" was introduced in 1975 by Haim Harari. The bottom quark was discovered in 1977 by the Fermilab E288 experiment team led by Leon M. Lederman, when collisions produced bottomonium. Kobayashi and Maskawa won the 2008 Nobel Prize in Physics for their explanation of CP-violation. While the name "beauty" is sometimes used, "bottom" became the predominant usage by analogy of "to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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