# Particle

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**Particle in a spherically symmetric potential**— In quantum mechanics, the particle in a spherically symmetric potential describes the dynamics of a particle in a potential which has spherical symmetry. The Hamiltonian for such a system has the form:hat{H} = frac{hat{p}^2}{2m 0} + V(r)where m 0 …92

**Particle velocity level**— The particle velocity level or the sound velocity level tells the ratio of a sound incidence in comparison to a reference level of 0 dB in a medium, mostly air.It shows the ratio of the particle velocity v 1 and the particle velocity v 0.The… …93

**Particle shower**— In particle physics, a shower is a cascade of secondary 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… …94

**Particle physics and representation theory**— There is a natural connection, first discovered by Eugene Wigner, between the properties of particles, the representation theory of Lie groups and Lie algebras, and the symmetries of the universe. According to it, the different states of an… …95

**Particle density**— The particle density or true density of a particulate solid or powder, is the density of the particles that make up the powder, in contrast to the bulk density, which measures the average density of a large volume of the powder in a specific… …96

**Particle in a ring**— In quantum mechanics, the case of a particle in a one dimensional ring is similar to the particle in a box. The Schrödinger equation for a free particle which is restricted to a ring (technically, whose configuration space is the circle S^1) is …97

**Particle horizon**— NOTOC In physical cosmology, particle horizon is the maximum distance from which particles could have traveled to the observer in the age of the universe. It represents the portion of the universe which we could have conceivably observed at the… …98

**Particle (ecology)**— In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater, however they eventually settle (rate determined by Stokes law) and accumulate as sediment. Some can enter the… …99

**Particle acceleration**— In a compressible sound transmission medium mainly air air particles get an accelerated motion: the particle acceleration or sound acceleration with the symbol a in metre/second sup2;. In acoustics or physics, acceleration (symbol: a ) is defined …100

**Particle beam cooling**— To be developed as a jump page related to particle accelerators Cooling techniques are important for the control the emittance of particle beams in particle accelerators. Usually, these techniques take advantage, in some way, of the electric or… …