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PVLAS
PVLAS (Polarizzazione del Vuoto con LASer, "polarization of the vacuum with laser") aims to carry out a test of quantum electrodynamics and possibly detect dark matter at the Department of Physics and National Institute of Nuclear Physics in Ferrara, Italy. It searches for vacuum polarization causing nonlinear optical behavior in magnetic fields. Experiments began in 2001 at the INFN Laboratory in Legnaro (Padua, Italy) and continue today with new equipment. Background Nonlinear electrodynamic effects in vacuum have been predicted since the earliest days of quantum electrodynamics (QED), a few years after the discovery of positrons. One such effect is vacuum magnetic birefringence, closely connected to elastic light-by-light interaction. The effect is extremely small and has never yet been observed directly. Although today QED is a very well-tested theory, the importance of detecting light-by-light interaction remains. First, QED has always been tested in the presence of charged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photon-photon Scattering
Two-photon physics, also called gamma–gamma physics, is a branch of particle physics that describes the Fundamental interaction, interactions between two photons. Normally, beams of light pass through each other unperturbed. Inside an optical material, and if the intensity of the beams is high enough, the beams may affect each other through a variety of Nonlinear optics, non-linear optical effects. In pure vacuum, some weak scattering of light by light exists as well. Also, above some threshold of this center-of-mass energy of the system of the two photons, matter can be matter creation, created. Astronomy Cosmological/intergalactic gamma rays Photon–photon interactions limit the spectrum of observed gamma-ray photons at moderate cosmological distances to a photon energy below around 20 GeV, that is, to a wavelength of greater than approximately . This limit reaches up to around 20 TeV at merely intergalactic distances. An analogy would be light traveling through a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axion
An axion () is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest as a possible component of cold dark matter. History Strong CP problem As shown by Gerard 't Hooft, strong interactions of the Standard Model, QCD, possess a non-trivial vacuum structure that in principle permits violation of the combined symmetries of charge conjugation and parity, collectively known as CP. Together with effects generated by weak interactions, the effective periodic strong CP-violating term, , appears as a Standard Model input – its value is not predicted by the theory, but must be measured. However, large CP-violating interactions originating from QCD would induce a large electric dipole moment (EDM) f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Electrodynamics
In particle physics, quantum electrodynamics (QED) is the Theory of relativity, relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomenon, phenomena involving electric charge, electrically charged particles interacting by means of exchange of photons and represents the quantum mechanics, quantum counterpart of classical electromagnetism giving a complete account of matter and light interaction. In technical terms, QED can be described as a perturbation theory (quantum mechanics), perturbation theory of the electromagnetic Quantum vacuum state, quantum vacuum. Richard Feynman called it "the jewel of physics" for its precision tests of QED, extremely accurate predictions of quantities like the anomalous magnetic moment of the electron and the Lamb shift of the energy levels of hydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum
A vacuum (: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective (neuter ) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a ''perfect'' vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term ''in vacuo'' is used to describe an object that is surrounded by a vacuum. The ''quality'' of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressur ... [...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 The National A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CERN Axion Solar Telescope
The CERN Axion Solar Telescope (CAST) is an experiment in astroparticle physics to search for axions originating from the Sun. The experiment, sited at CERN in Switzerland, was commissioned in 1999 and came online in 2002 with the first data-taking run starting in May 2003. The successful detection of solar axions would constitute a major discovery in particle physics, and would also open up a brand new window on the astrophysics of the solar core. CAST is currently the most sensitive axion helioscope. Theory and operation If the axions exist, they may be produced in the Sun's core when X-rays scatter off electrons and protons in the presence of strong electric fields. The experimental setup is built around a 9.26 m long decommissioned test magnet for the LHC capable of producing a field of up to . This strong magnetic field is expected to convert solar axions back into X-rays for subsequent detection by X-ray detectors. The telescope observes the Sun for about 1.5 h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAMA/LIBRA
The DAMA/LIBRA experiment is a particle detector experiment designed to detect dark matter using the direct detection approach, by using a matrix of NaI(Tl) scintillation detectors to detect dark matter particles in the galactic halo. The experiment aims to find an annual modulation of the number of detection events, caused by the variation of the velocity of the detector relative to the dark matter halo as the Earth orbits the Sun. It is located underground at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. It is a follow-on to the DAMA/NaI experiment which observed an annual modulation signature over 7 annual cycles (1995-2002). The experiment was first proposed by Dr. Pierluigi Belli, who is now the research director of the Italian National Institute of Nuclear Physics. While DAMA/LIBRA has published exciting results, the validity of those results has been widely disputed; they have not made their data or practices publicly available, and their methods of backgro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAMA/NaI
The DAMA/NaI experiment investigated the presence of dark matter particles in the galactic halo by exploiting the model-independent annual modulation signature. Based on the Earth's orbit around the Sun and the Solar System's speed with respect to the center of the galaxy (which on short time scales can be considered constant), the Earth should be exposed to a higher flux of dark matter particles around June 1, when its orbital speed is added to that of the Solar System with respect to the galaxy and to a smaller one around December 2, when the two velocities are subtracted. The annual modulation signature is distinctive since the effect induced by dark matter particles must simultaneously satisfy many requirements. Description The experimental set-up was located deep underground in the Laboratori Nazionali del Gran Sasso in Italy. The experimental set-up was made by nine 9.70 kg low-radioactivity scintillating thallium-doped sodium iodide crystals aI(Tl) Each crys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Scientific
World Scientific Publishing is an academic publisher of scientific, technical, and medical books and journals headquartered in Singapore. The company was founded in 1981. It publishes about 600 books annually, with more than 170 journals in various fields. In 1995, World Scientific co-founded the London-based Imperial College Press together with the Imperial College of Science, Technology and Medicine. Company structure The company head office is in Singapore. The Chairman and Editor-in-Chief is Dr Phua Kok Khoo, while the Managing Director is Doreen Liu. The company was co-founded by them in 1981. Imperial College Press In 1995 the company co-founded Imperial College Press, specializing in engineering, medicine and information technology Information technology (IT) is a set of related fields within information and communications technology (ICT), that encompass computer systems, software, programming languages, data processing, data and information processing, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Budker Institute Of Nuclear Physics
The Budker Institute of Nuclear Physics (BINP) is one of the major centres of advanced study of nuclear physics in Russia. It is located in the Siberian town Akademgorodok, on Academician Lavrentyev Avenue, Novosibirsk, Academician Lavrentiev Avenue. The institute was founded by Gersh Budker in 1959. Following his death in 1977, the institute was renamed in honour of Budker. Despite its name, the centre was not involved either with military atomic science or nuclear reactors instead, its concentration was on high-energy physics (particularly Plasma (physics), plasma physics) and particle physics. In 1961 the institute began building :ru:ВЭП-1, VEP-1,A. N. Skrinsly"Accelerator field development at Novosibirsk (history, status, prospects)", Particle Accelerator Conference, Proceedings of the 1995.V. N. Baier, "Forty years of acting electron-positron colliders"arXiv:hep-ph/0611201 [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen L
Stephen or Steven is an English first name. It is particularly significant to Christians, as it belonged to Saint Stephen ( ), an early disciple and deacon who, according to the Book of Acts, was stoned to death; he is widely regarded as the first martyr (or " protomartyr") of the Christian Church. The name, in both the forms Stephen and Steven, is often shortened to Steve or Stevie. In English, the female version of the name is Stephanie. Many surnames are derived from the first name, including Stephens, Stevens, Stephenson, and Stevenson, all of which mean "Stephen's (son)". In modern times the name has sometimes been given with intentionally non-standard spelling, such as Stevan or Stevon. A common variant of the name used in English is Stephan ( ); related names that have found some currency or significance in English include Stefan (pronounced or in English), Esteban (often pronounced ), and the Shakespearean Stephano ( ). Origins The name "Stephen" (and its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Field
A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function (mathematics), function assigning a Euclidean vector, vector to each point of space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
