File Lead shielding.jpg thumb Lead bricks are commonly used as radiation shielding. Lead shielding refers to the use of lead as a form of radiation protection to radiation shield shield people or objects from radiation . Lead can effectively attenuate certain kinds of radiation because of its high density and high atomic number principally, it is effective at stopping alpha ray s, gamma ray s, and x ray s. Lead s high density is caused by the combination of its high atomic mass and the relatively small size of its bond lengths and atomic radius. The high atomic mass means that more electron s are needed to maintain a neutral charge and the small bond length and a small atomic radius means that many atoms can be packed into a particular lead structure. Because of lead s density and large number of electrons, it is well suited to scattering x rays and gamma rays. These rays form photon s, a type of boson , which impart energy onto electrons when they come into contact. Without a lead shield, the electrons within a person s body would be affected, which could damage their DNA and cause cancer . When the radiation attempts to pass through lead, its electrons absorb and scatter the energy. Eventually though, the lead will degrade from the energy to which it is exposed. However, lead is not effective against all types of radiation. High energy electrons including beta radiation incident on lead may create bremsstrahlung radiation, which is potentially more dangerous to tissue than the original radiation. Furthermore, lead is not a particularly effective absorber of neutron radiation . Use Lead is used for shielding in x ray machines, nuclear power plant s, Laboratory lab s, military equipment, and other places radiation may be encountered. There is great variety in the types of shielding available both to protect people and to shield equipment and experiments. Personal shielding includes lead aprons such as the familiar garment used during dental Radiography x rays , thyr ... more details
Image urabe instal.jpg thumb Masayoshi Urabe live at the Instal festival, Glasgow, 2004 Nihongo Masayoshi Urabe Urabe Masayoshi born 1965 is a Japanese musician, best known for his intensely physical style of free improvisation on the alto saxophone and his deployment of long, laden silences. He has sometimes been compared to the late Japanese free jazz altoist Kaoru Abe . br He has played with many underground musicians in Japan, including Chie Mukai Ch SHIZU , Kan Mikami Sanjah , Hiroshi Hasegawa Astro band Astro , C.C.C.C. band C.C.C.C. , Junko Hijokaidan and the psychedelic rock group Kousokuya . Recently he formed the group Sanjah, with folk singer Kan Mikami and drummer Toshi Ishizuka . He also performs with the Paris based dancer Yukiko Nakamura . Discography Solo Solo LP CD PSF, 1996 Ju A Brute 2LP no label, 2000 Rock n Roll Breathing video There, 2001 Urklang CD Tiliqua, 2001 Soingyokusaiseyo LP Elevage de Poussiere, 2002 Ware wa seidai no kyojo zo CD PSF, 2003 V.A., Amaterasu 2CD Fractal, 2003 V.A., Undecided CD PSF, 2004 V.A., Somethings 1 CD Last Visible Dog, 2007 The Flag of Midsummer CD PSF, 2008 Collaborations Nazareth CD w Ch SHIZU PSF, 1993 The Dark Spot CD w Kousokuya PSF, 1997 Duo 1988 LP w Hiroshi Hasegawa Siwa, 1999 Masayoshi Urabe & Gary Smith CD w Gary Smith guitarist Gary Smith Paratactile, 2001 Dual Anarchism LP w Chie Mukai Siwa, 2002 Dual Anarchism video w Chie Mukai There, 2002 Chi no kioku video w Yuji Itsumi PSF, 2003 V.A., PSF & Alchemy 20th Anniversary Live CD w Junko PSF, 2005 Musen Izu CD w Sanjah PSF, 2006 Samples Urabe Breathes on Cory Allen musician Cory Allen s album Gesemi Tropisms Bremsstrahlung , 2005 References Interview. Opprobrium , issue 5, July 1998. pp. 3 10. English External links http www.lethe voice.com 2002 1003 6 uk.html Photographs and movie of Urabe at Lethe Voice festival http www.monoculartimes.co.uk monomusic masayoshi urabe.shtml Live review Leeds, 2002 Persondata name Urabe, Masayoshi alter ... more details
refimprove date October 2009 cleanup date October 2009 John M.J. Madey is a professor of Physics at the University of Hawaii at Manoa , ref www.phys.hawaii.edu people faculty madey.html ref a former director of the Free Electron Laser Centre at Duke University , and formerly a tenured professor at Stanford University. He ist best known for his development of the free electron laser FEL at Stanford University in the 1970s. ref New Light What is free electron laser, Isamu Sato, International Symposium of Maxillofacial and Oral regenerative biology in Okayama 2003 ref ref Stimulated Emission of Bremsstrahlung in a Periodic Magnetic field Magnetic Field , John Madey, J. Appl. Phys. 42, 1906 1971 ref Stanford University refused to patent this idea so Madey filed for a patent on his own. In the following, he developed an innovative laser research program which was highly regarded in the scientific community . An opportunity arose for Madey to leave Stanford, taking a tenure d position at the Physics Department of Duke University, which Madey accepted in 1988, moving his FEL research laboratory with him in 1989. This laboratory contained substantial equipment which required Duke to build an addition to its physics building to house the lab. In addition, while at Stanford, Madey had obtained sole ownership of two patents practiced by some of the equipment in the FEL lab. At Duke, Madey served for almost a decade as director of the FEL lab. During that time the lab continued to achieve success both in securing research funding and in generating scientific breakthroughs. A dispute arose, however, between Madey and Duke. Duke contends that, despite his scientific prowess, Madey had ineffectively managed the lab. Madey contends that Duke sought to use the lab s equipment for research areas outside the allocated scope of certain government funding, and that when he objected, Duke sought to remove him as lab director. Duke eventually removed Madey as director of the lab in 1997. ... more details
Technical date September 2010 Kramers opacity law describes the behavior of the opacity optics opacity in terms of the ambient density and temperature when the opacity is dominated by ionization bound free absorption the ionization of a bound electron or free free absorption also called bremsstrahlung . ref Phillips 1999 , p. 92. ref It is named after the Dutch people Dutch physicist Hendrik Kramers , who first derived the form in 1923. ref name Carroll274 Carroll 1996 , p. 274. ref The general functional form of the opacity law is math bar kappa kappa 0 rho T 7 2 , math where math bar kappa math is the average opacity, math kappa 0 math is a parameter that encapsulates fractional abundances and quantum mechanical corrections, math rho math is the density, and math T math is the temperature. This form alone is useful for understanding how changes in either the density or temperature will affect the opacity, which in turn is important in understanding radiative transfer , particularly in stellar atmosphere s. ref Carroll 1996 , p. 274 276. ref The specific forms for bound free and free free are Bound free math bar kappa 4.34 times 10 25 frac g bf t Z 1 X rho T 7 2 rm cm 2 g 1 , math Free free math bar kappa 3.68 times 10 22 g ff 1 Z 1 X rho T 7 2 rm cm 2 g 1 . math Here, math g bf math and math g ff math are the Gaunt factor s associated with bound free and free free transitions, respectively, and are quantum mechanical correction terms. The math t math is an additional correction factor, typically having a value between 1 and 100. math Z math is the fractional abundance by mass of elements heavier than hydrogen , and math X math is the fractional abundance by mass of hydrogen. ref name Carroll274 References Reflist Bibliography Cite book author Carroll, Bradley Ostlie, Dale year 1996 title Modern Astrophysics publisher Addison Wesley location url http books.google.com books?id yXR QgAACAAJ Cite book author Phillips, A. C. year 1999 title The Physics of Stars publish ... more details
jet events in e sup sup e sup sup annihilation and evidence for gluon bremsstrahlung journal Physics ... Evidence for gluon bremsstrahlung in e sup sup e sup sup annihilations at high energies journal Physics ... more details
Unreferenced date January 2012 In particle physics , a shower is a cascade of secondary subatomic particle 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 of showers Image Schematic of a particle shower.svg thumb right The start of an electromagnetic shower. 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 hadron s i.e. nucleon s and other particles made of quark s , 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 Electron volt MeV , below which photoelectric effect and Compton scattering are dominant , photons interact with matter primarily via pair production &mdash that is, they convert into an electron positron pair, interacting with an atomic nucleus or electron in order to conserve momentum . High energy electrons and positrons primarily emit photons, a process called bremsstrahlung . These two processes continue in turn, until the remaining particles have lower energy. Electrons and photons then lose energy via scattering until they are absorbed by atoms. The shower depth is approximately determined by the relation math X X 0 frac ln E 0 E c ln2 , math where math X 0 math is the radiation length of the matter, and math E c math is the critical energy . It logarithmically depends on the initial energy. The characteristic radius of the shower is the Moli re radius . Hadronic showers A hadronic shower ... more details
Unreferenced date March 2007 file The MAGIC Telescope at night.jpg thumb 300px MAGIC telescope MAGIC , a Cherenkov telescope in operation on the Canary island of La Palma . On foggy nights, the lasers that are used to focus the mirrors can be seen. The IACT or Imaging Atmospheric Cherenkov Technique is the method whereby very high energy gamma ray photon s in the 50 GeV to 50 TeV range can be detected by ground based telescope s. There are currently four major ground based telescopes including CANGAROO III , MAGIC telescope MAGIC , HESS and VERITAS . Currently under design are the Cherenkov Telescope Array CTA , and the Advanced Gamma ray Imaging System AGIS . Due to the rapidly falling flux of gamma ray photons from cosmos cosmic sources in this energy regime, space based detectors become ineffective due to their small collection areas which are often limited to some tens or hundreds of square centimeters. In the case of the IACT, the Earth s atmosphere is used as the detection medium, implying a collection area of many hundreds of square meters. This enables IACT instruments to detect gamma ray photons in an energy regime inaccessible to space based instruments. The IACT works by imaging the very brief flash of Cherenkov effect Cherenkov radiation generated by the cascade of relativistic charged particle s produced when a very high energy gamma ray strikes the atmosphere. This shower of charged particles, known as an Air shower physics Extensive Air Shower EAS is initiated at an altitude of 10 20 km. The incoming gamma ray photon undergoes pair production in the vicinity of the atomic nucleus nucleus of an atmosphere atmospheric molecule . The electron positron pair produced are of extremely high energy and immediately undergo Bremsstrahlung or Braking Radiation . This radiation produced is itself extremely energetic, with many of the photons undergoing further pair production. A cascade of charged particles ensues which, due to its extreme energy, ... more details
A super star cluster SSC is a very large region that is thought to be the precursor of a globular cluster . ref name gallagher02 cite journal author Gallagher & Grebel year 2002 title Extragalactic Star Clusters Speculations on the Future journal Extragalactic Star Clusters, IAU Symposium pages 207 bibcode 2002IAUS..207..745G arxiv astro ph 0109052 ref They typically contain a very large number of T Tauri Star young , OB star massive stars that ionize a surrounding H II region , similar to our Milky Way Galaxy Milky Way s so called Ultra dense H II regions UDHIIs . ref name kobulnicky99 cite journal author Kobulnicky & Johnson year 1999 title Signatures of the Youngest Starbursts Optically Thick Thermal Bremsstrahlung Radio Sources in Henize 2 10 journal ApJ pages 154 166 issue 1 volume 527 bibcode 1999ApJ...527..154K doi 10.1086 308075 last2 Johnson first2 Kelsey E. arxiv astro ph 9907233 ref An SSC s H II region is in turn surrounded by a cocoon of cosmic dust dust . In many cases, the stars and the H II regions will be invisible to optical observations due to high levels of extinction astronomy extinction . As a result, the youngest SSCs are best observed in radio astronomy radio and infrared astronomy infrared . ref name johnson04 cite journal author Johnson year 2004 title Extragalactic Ultracompact HII Regions Probing the Birth Environments of Super Star Clusters journal Astronomical Society of the Pacific Conference Series pages 322 volume 527 bibcode 2004ASPC..322..339J arxiv astro ph 0405125 ref The unique characteristics of SSCs are their large electron Density densities math n e 10 3 math math 10 6 math cm math 3 math and pressure s math P math Boltzmann s constant math k b math math 10 7 math math 10 10 math Kelvin K cm math 3 math . ref name johnson04 While there are many examples of SSCs in other galaxies, Westerlund 1 may be the only cluster in the Milky Way deserving of the title. ref cite news date March 22, 2005 title Young and Exotic Stellar Zoo E ... more details
Infobox scientist name Bj rn Wiik image filename only image size caption birth date Birth date 1937 2 17 df y birth place Bruvik , Norway death date Death date and age 1999 2 26 1937 2 17 df y death place Hamburg , Germany residence citizenship nationality ethnicity fields Particle physics workplaces Stanford Linear Accelerator Center br German Electron Synchrotron DESY alma mater doctoral advisor academic advisors doctoral students notable students known for author abbrev bot author abbrev zoo influences influenced awards religion signature filename only footnotes Bj rn Havard Wiik born 17 February 1937 in Bruvik , Norway died 26 February 1999 in Hamburg, Germany was a Norwegian elementary particle physicist, noted for his role on the experiment that produced the first experimental evidence for gluons and for his influential role on later accelerator projects. Biography Bj rn Wiik lived in his home town Bruvik until he began his physics studies at Germany s Technical University of Darmstadt . In 1965, he got his doctorate degree there. Two years later he began working at the Stanford Linear Accelerator Center in Menlo Park, California . In 1972, Wiik returned to Germany, to the German Electron Synchrotron DESY in Hamburg where, four years later, he was appointed lead scientist. In 1978, Wiik and his collaborators began using DESY s newly commissioned PETRA electron positron storage ring to look for hard gluon bremsstrahlung events that would provide experimental support for the existence and role of gluons in mediating strong interactions among quarks . Wiik and his team soon observed and reported a type of event never described before three particle jets whose momenta lay in a plane. These results, widely believed to represent the after effects of two quarks plus a gluon, were soon confirmed by many other groups. In 1995, the European Physical Society awarded its Prize for High Energy and Particle Physics to four physicists representing the TASSO collaboration Pau ... more details
of Bremsstrahlung X rays. In the case of beta radiation positron s , the gamma radiation from ... the radiation interacts with the shielding material and creates bremsstrahlung Secondary radiation ... produces bremsstrahlung and Auger electron s, which are below the detector s energy threshold ... more details
energy electrons are produced. Such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung ... by electrons either in orbitals outside of the nucleus, or while being accelerated to produce Bremsstrahlung type radiation , ref Bremsstrahlung radiation is braking radiation , but acceleration is being ... at 10 to 20 MeV, and known to be produced by the Bremsstrahlung mechanism. Another example is gamma ... electron positron annihilation , neutral pion decay , bremsstrahlung , inverse Compton scattering ... by bremsstrahlung as they collide with and slowed by atoms in the atmosphere. High energy gamma rays ... bremsstrahlung at energies of tens of MeV or more are produced when cosmic ray electrons interact ... of relativistic speed charged particles, which produce gamma rays bremsstrahlung when these charged ... to the production of high energy photons in megavoltage radiation therapy machines see bremsstrahlung ... again by inverse Compton scattering, synchrotron radiation , or bremsstrahlung, likely produce ... more details
cross sections. Therefore the vast majority of ions end up expending their energy on bremsstrahlung ... and bremsstrahlung . Although it makes a useful neutron generator, the apparatus is not intended ... will leak energy at a rapid rate due to bremsstrahlung produced when electron s in the plasma physics ... 2 Nuclide Link tritium 3 reaction and can be considered a measure of the economic potential. Bremsstrahlung ... x ray radiation of 10 30 keV energy Bremsstrahlung . The Sun and stars are Opacity optics opaque to x ... sub P sub Bremsstrahlung sub Nuclide deuterium 2 Nuclide tritium 3 50 140 Nuclide deuterium 2 Nuclide ... of fusion to Bremsstrahlung power will likely be significantly lower for several reasons. For one ... ions, which then lose energy to the electrons by collisions, which in turn lose energy by Bremsstrahlung ... confinement scheme. Finally, all channels of energy loss other than Bremsstrahlung have been neglected ... confinement will be poor, too. The temperatures maximizing the fusion power compared to the Bremsstrahlung ... operating point for Nuclide Link deuterium 2 Nuclide Link tritium 3 very much because the Bremsstrahlung ... 2 Nuclide Link helium 3 , Bremsstrahlung losses will be a serious, possibly prohibitive problem ... p sup sup Nuclide Link boron 11 the Bremsstrahlung losses appear to make a fusion reactor using ... more details
losses. While all three are IEC devices, only the last is actually a fusor . BremsstrahlungBremsstrahlung ... a surface. One oft presented concern for fusor operation is bremsstrahlung . In http hdl.handle.net ... , Todd Rider shows that a quasineutral isotropic plasma will lose energy due to Bremsstrahlung at a rate ... more details
Expert verify date May 2009 Citation style date September 2009 quantum stub Quantum 1 f noise is claimed to be an intrinsic part of quantum mechanics see the debate section below . The model is based on the scattering of different particles off one another in solid state physics. Quantum 1 f noise is also claimed to be a source of Chaos theory chaos in such systems. Other noise data sets 1 f noise has also recently claimed to be seen in higher ordered self constructing functions, as well as complex systems, both biological, chemical, and physical. The theory The basic derivation of quantum 1 f was made by Dr. Peter Handel, a theoretical physicist at the UMSL University of Missouri St. Louis , and published in Physical Review A , in August 1980. Several hundreds of papers have been published by many authors on Handel s quantum theory on 1 f noise, which is a new aspect of quantum mechanics. They verified, applied, and further developed the quantum 1 f noise formulas. See the General Quantum 1 f Bibliography at http www.umsl.edu handel. Aldert van der Ziel , the nestor of the electronic noise field, verified and applied it in many devices and systems, together with dozens of his PhD students. It is described in the last of his 12 books Noise in electronic devices and circuits published by Wiley in 1986. He also updated and generalized many verifications, practical applications, etc., in his authoritative 1988 review Unified Description of 1 f Noise in Proceedings of IEEE. ref Cite doi 10.1109 5.4401 ref For more on Quantum 1 f noise, see P.H. Handel Phys. Rev. Letters of June 16, 1975 2 papers , and also 1 f Macroscopic Quantum Fluctuations of Electric Currents Due to Bremsstrahlung with Infrared Radiative Corrections , Zeitschrift fuer Naturforschung 30a, p. 1201 1975 . For the coherent quantum 1 f effect, see the Physica Status Solidi paper of 1996 , the Transactions in Electron Devices paper of 1994, and the Proceedings of IEEE paper with graduate student Adam ... more details
Event generators are software library computer science libraries that generate simulated high energy particle physics event particle physics events . ref http arjournals.annualreviews.org doi abs 10.1146 annurev.nucl.55.090704.151505 M. L. Mangano & T. J. Stelzer, Ann. Rev. Nucl. Part. Sci. 55, 555 2005 . ref ref http arxiv.org abs hep ph 0403045 M. A. Dobbs et al. , hep ph 0403045. ref They randomly generate events as those produced in particle accelerators , collider experiments or during the initial phases of the Universe creation. Events come in different types called processes as discussed in the Automatic calculation of particle interaction or decay article. Despite the simple structure of the tree level perturbation theory perturbative quantum field theory description of the collision and radioactive decay decay processes in an event, the observed high energy process usually contains significant amount of modifications, like photon and gluon bremsstrahlung or loop Feynman diagram diagram corrections, that usually are too complex to be easily evaluated in real calculations directly on the diagrammatic level. Furthermore, the non perturbative nature of Quantum chromodynamics QCD bound state s makes it necessary to include information that is beyond the reach of perturbative quantum field theory, and well beyond present ability of computation in lattice QCD . And in collisional systems more complex than a few lepton s and hadron s e.g. heavy ion collisions , the collective behavior of the system would involve a phenomenology particle physics phenomenological description that also cannot be easily obtained from the fundamental field theory by a simple calculus. Any realistic test of the underlying physical process in a particle accelerator experiment , therefore, requires an adequate inclusion of these complex behaviors surrounding the actual process. Based on the fact that in most processes a factorization of the full process into individual problems is possible ... more details
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