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Gaisser–Hillas Function
The Gaisser–Hillas function is used in astroparticle physics. It parameterizes the longitudinal particle density in a cosmic ray Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the ... air shower. The function was proposed in 1977 by Thomas K. Gaisser and Anthony Michael Hillas. The number of particles N(X) as a function of traversed atmospheric depth X is expressed as :N(X)= N_\text\left(\frac\right)^\exp\left(\frac\right), where N_\text is maximum number of particles observed at depth X_\text, and X_0 and \lambda are primary mass and energy dependent parameters. Using substitutions n=\frac, x=\frac and m=\frac the function can be written in an alternative one-parametric (''m'') form as :n(x)=\left(\frac\right)^m\exp(m-x)=\frac=\exp\left(m\,(\ln x-\ln m)-(x-m)\right)\, . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astroparticle Physics
Astroparticle physics, also called particle astrophysics, is a branch of particle physics that studies elementary particles of astrophysical origin and their relation to astrophysics and cosmology. It is a relatively new field of research emerging at the intersection of particle physics, astronomy, astrophysics, detector physics, relativity, solid state physics, and cosmology. Partly motivated by the discovery of neutrino oscillation, the field has undergone rapid development, both theoretically and experimentally, since the early 2000s. History The field of astroparticle physics is evolved out of optical astronomy. With the growth of detector technology came the more mature astrophysics, which involved multiple physics subtopics, such as mechanics, electrodynamics, thermodynamics, plasma physics, nuclear physics, relativity, and particle physics. Particle physicists found astrophysics necessary due to difficulty in producing particles with comparable energy to those found in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parametric Equation
In mathematics, a parametric equation expresses several quantities, such as the coordinates of a point (mathematics), point, as Function (mathematics), functions of one or several variable (mathematics), variables called parameters. In the case of a single parameter, parametric equations are commonly used to express the trajectory of a moving point, in which case, the parameter is often, but not necessarily, time, and the point describes a curve, called a parametric curve. In the case of two parameters, the point describes a Surface (mathematics), surface, called a parametric surface. In all cases, the equations are collectively called a parametric representation, or parametric system, or parameterization (also spelled parametrization, parametrisation) of the object. For example, the equations \begin x &= \cos t \\ y &= \sin t \end form a parametric representation of the unit circle, where is the parameter: A point is on the unit circle if and only if there is a value of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Density (packed Density)
{{refimprove, date=September 2016 The particle mass density or particle density of a material (such as particulate solid or powder) is the mass density of the particles that make up the powder. Particle density is in contrast to the ''bulk density'', which measures the average density of a large volume of the powder in a specific medium (usually air). The particle density is a relatively well-defined quantity, as it is not dependent on the degree of compaction of the solid, whereas the bulk density has different values depending on whether it is measured in the freely settled or compacted state (tap density). However, a variety of definitions of particle density are available, which differ in terms of whether pores are included in the particle volume, and whether voids are included. Measurement The measurement of particle density can be done in a number of ways: Archimedes' principle The powder is placed inside a pycnometer of known volume, and weighed. The pycnometer is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmic Ray
Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own galaxy, and from distant galaxies. Upon impact with Earth's atmosphere, cosmic rays produce showers of secondary particles, some of which reach the surface, although the bulk are deflected off into space by the magnetosphere or the heliosphere. Cosmic rays were discovered by Victor Hess in 1912 in balloon experiments, for which he was awarded the 1936 Nobel Prize in Physics. Direct measurement of cosmic rays, especially at lower energies, has been possible since the launch of the first satellites in the late 1950s. Particle detectors similar to those used in nuclear and high-energy physics are used on satellites and space probes for research into cosmic rays. Data from the Fermi Space Telescope (2013) have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Shower (physics)
Air showers are extensive Particle shower, cascades of subatomic particles and ionized nuclei, produced in the Earth's atmosphere, atmosphere when a ''primary'' cosmic ray enters the atmosphere. Particles of cosmic radiation can be protons, Atomic nucleus, nuclei, electrons, photons, or (rarely) positrons. Upon entering the atmosphere, they interact with molecules and initiate a particle cascade that lasts for several generations, until the energy of the primary particle is fully converted. If the primary particle is a hadron, mostly light mesons like pions and kaons are produced in the first interactions, which then fuel a hadronic shower component that produces shower particles mostly through pion decay. Primary photons and electrons, on the other hand, produce mainly electromagnetic showers. Depending on the energy of the primary particle, the detectable size of the shower can reach several kilometers in diameter. The air shower phenomenon was unknowingly discovered by Bruno Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas K
Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (other) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the Apostle * Thomas (bishop of the East Angles) (fl. 640s–650s), medieval Bishop of the East Angles * Thomas (Archdeacon of Barnstaple) (fl. 1203), Archdeacon of Barnstaple * Thomas, Count of Perche (1195–1217), Count of Perche * Thomas (bishop of Finland) (1248), first known Bishop of Finland * Thomas, Earl of Mar (1330–1377), 14th-century Earl, Aberdeen, Scotland Geography Places in the United States * Thomas, Idaho * Thomas, Illinois * Thomas, Oklahoma * Thomas, Oregon * Thomas, South Dakota * Thomas, Virginia * Thomas, Washington * Thomas, West Virginia * Thomas County (other) * Thomas Township (other) Elsewhere * Thomas Glacier (Greenland) Arts and entertainment * ''Thomas'' (Burton novel), a 1969 nove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anthony Michael Hillas
Alexander Michael Hillas (June 1932 – 26 November 2017) was an English cosmic ray physicist. He is known for the Gaisser–Hillas function, the Hillas parameters, and MOCCA, a Monte Carlo computer code used for simulation of extensive air showers (EASs) in the energy range from 1012 (tera-) eV to 1021 (zetta-) eV. Early life and education Born in a village near Leeds, A. Michael Hillas attended school in York. He studied at Bootham School from 1947 to 1950. In secondary school, he showed remarkable signs of talent for computation. At the University of Leeds, he graduated with a B.Sc. in physics in 1955 with First Class Honours and with a Ph.D. in 1958. His Ph.D. thesis is entitled ''The interaction of stopped negative muons with atomic nuclei''. As a postdoc, Hillas held a fellowship at Harwell Science and Innovation Campus. In 1959 at Harwell, Michael Hillas and Thomas Edwin "Ted" Cranshaw (1922–2016) measured, with extreme accuracy, the charge difference between the proton an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pergamon Press
Pergamon Press was an Oxford-based publishing house, founded by Paul Rosbaud and Robert Maxwell, that published scientific and medical books and journals. Originally called Butterworth-Springer, it is now an imprint of Elsevier. History The core company, Butterworth-Springer, started in 1948 to bring the "Springer know-how and techniques of aggressive publishing in science"Joe Haines (1988) ''Maxwell'', Houghton Mifflin, p. 137. to Britain. Paul Rosbaud was the man with the knowledge. When Maxwell acquired the company in 1951, Rosbaud held a one-quarter share. They changed the house name to Pergamon Press, using a logo that was a reproduction of a Greek coin from Pergamon. Maxwell and Rosbaud worked together growing the company until May 1956, when, according to Joe Haines, Rosbaud was sacked. When Pergamon Press started it had only six serials and two books. Initially the company headquarters was in Fitzroy Square in West End of London. In 1959, the company moved into He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
