|
CLEO (particle Detector)
CLEO was a general purpose particle detector at the Cornell Electron Storage Ring (CESR), and the name of the collaboration of physicists who operated the detector. The name CLEO is not an acronym; it is short for Cleopatra and was chosen to go with CESR (pronounced Caesar). CESR was a particle accelerator designed to collide electrons and positrons at a center-of-mass energy of approximately 10 GeV. The energy of the accelerator was chosen before the first three bottom quark Upsilon resonances were discovered between 9.4 GeV and 10.4 GeV in 1977. The fourth Υ resonance, the Υ(4S), was slightly above the threshold for, and therefore ideal for the study of, B meson production. CLEO was a hermetic detector that in all of its versions consisted of a tracking system inside a solenoid magnet, a calorimeter, particle identification systems, and a muon detector.CLEO I NIMCLEO II NIM The detector underwent five major upgrades over the course of its thirty-year lifetime, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Detector
In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a particle accelerator. Detectors can measure the particle energy and other attributes such as momentum, spin, charge, particle type, in addition to merely registering the presence of the particle. Examples and types Many of the detectors invented and used so far are ionization detectors (of which gaseous ionization detectors and semiconductor detectors are most typical) and scintillation detectors; but other, completely different principles have also been applied, like Čerenkov light and transition radiation. Historical examples *Bubble chamber * Wilson cloud chamber (diffusion chamber) * Photographic plate ;Detectors for radiation protection The following types of particle detector ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Lepton
The tau (), also called the tau lepton, tau particle, tauon or tau electron, is an elementary particle similar to the electron, with negative electric charge and a spin of . Like the electron, the muon, and the three neutrinos, the tau is a lepton, and like all elementary particles with half-integer spin, the tau has a corresponding antiparticle of opposite charge but equal mass and spin. In the tau's case, this is the "antitau" (also called the ''positive tau''). Tau particles are denoted by the symbol and the antitaus by . Tau leptons have a lifetime of and a mass of (compared to for muons and for electrons). Since their interactions are very similar to those of the electron, a tau can be thought of as a ''much'' heavier version of the electron. Because of their greater mass, tau particles do not emit as much bremsstrahlung radiation as electrons; consequently they are potentially much more highly penetrating than electrons. Because of its short lifetime, the range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Energy
The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United States. The DOE oversees the U.S. nuclear weapons program, nuclear reactor production for the United States Navy, energy-related research, and domestic energy production and energy conservation. The DOE was created in 1977 in the aftermath of the 1973 oil crisis. It sponsors more physical science research than any other U.S. federal agency, the majority of which is conducted through its system of National Laboratories. The DOE also directs research in genomics, with the Human Genome Project originating from a DOE initiative. The department is headed by the Secretary of Energy, who reports directly to the president of the United States and is a member of the Cabinet. The current Secretary of Energy is Jennifer Granholm, who has served ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Science Foundation
The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health. With an annual budget of about $8.3 billion (fiscal year 2020), the NSF funds approximately 25% of all federally supported basic research conducted by the United States' colleges and universities. In some fields, such as mathematics, computer science, economics, and the social sciences, the NSF is the major source of federal backing. The NSF's director and deputy director are appointed by the President of the United States and confirmed by the United States Senate, whereas the 24 president-appointed members of the National Science Board (NSB) do not require Senate confirmation. The director and deputy director are responsible for administration, planning, budgeting and day-to-day operations of the foundation, while t ... [...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] |
Flavor Changing Neutral Current
In particle physics, flavor-changing neutral currents or flavour-changing neutral currents (FCNCs) are hypothetical interactions that change the flavor of a fermion without altering its electric charge. Details If they occur in nature (as reflected by Lagrangian interaction terms), these processes may induce phenomena that have not yet been observed in experiment. Flavor-changing neutral currents may occur in the Standard Model beyond the tree level, but they are highly suppressed by the GIM mechanism. Several collaborations have searched for FCNC. The Tevatron CDF experiment observed evidence of FCNC in the decay of the strange B-meson to phi mesons in 2005. FCNCs are generically predicted by theories that attempt to go beyond the Standard Model, such as the models of supersymmetry or technicolor. Their suppression is necessary for an agreement with observations, making FCNCs important constraints on model-building. Example Consider a toy model in which an undiscovered boson ... [...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] |
ARGUS (experiment)
ARGUS (A Russian-German-United States-Swedish Collaboration; later joined by Canada and the former Yugoslavia) was a particle physics experiment that ran at the electron–positron collider ring DORIS II at the German national laboratory DESY. Its aim was to explore properties of charm and bottom quarks. Its construction started in 1979, the detector was commissioned in 1982 and operated until 1992. The ARGUS detector was a hermetic detector with 90% coverage of the full solid angle. It had drift chambers, a time-of-flight system, an electromagnetic calorimeter and a muon chamber system. It is the first experiment that observed the mixing of the B mesons into its antiparticle, the anti-B meson (in 1987). This observation led to the conclusion that the second-heaviest quark – the bottom quark – could under certain circumstances convert into a different, hitherto unknown quark, which had to have a huge mass. This quark, the top quark, was discovered in 1995 at Fermilab.Abe, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PETRA
Petra ( ar, ٱلْبَتْرَاء, Al-Batrāʾ; grc, Πέτρα, "Rock", Nabataean Aramaic, Nabataean: ), originally known to its inhabitants as Raqmu or Raqēmō, is an historic and archaeological city in southern Jordan. It is adjacent to the mountain of Jebel al-Madhbah, Jabal Al-Madbah, in a Depression (geology), basin surrounded by mountains forming the eastern flank of the Arabah valley running from the Dead Sea to the Gulf of Aqaba. The area around Petra has been inhabited from as early as 7000 BC, and the Nabataeans might have settled in what would become the capital city of Nabataean Kingdom, their kingdom as early as the 4th century BC. Archaeological work has only discovered evidence of Nabataean presence dating back to the second century BC, by which time Petra had become their capital. The Nabataeans were nomadic Arabs who invested in Petra's proximity to the incense trade routes by establishing it as a major regional trading hub. The trading business gained ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPEAR
A spear is a pole weapon consisting of a shaft, usually of wood, with a pointed head. The head may be simply the sharpened end of the shaft itself, as is the case with fire hardened spears, or it may be made of a more durable material fastened to the shaft, such as bone, flint, obsidian, iron, steel, or bronze. The most common design for hunting or combat spears since ancient times has incorporated a metal spearhead shaped like a triangle, lozenge, or leaf. The heads of fishing spears usually feature barbs or serrated edges. The word '' spear'' comes from the Old English '' spere'', from the Proto-Germanic ''speri'', from a Proto-Indo-European root ''*sper-'' "spear, pole". Spears can be divided into two broad categories: those designed for thrusting as a melee weapon and those designed for throwing as a ranged weapon (usually referred to as javelins or darts). The spear has been used throughout human history both as a hunting and fishing tool and as a weapon. Along ... [...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 for deca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
