Glossary Radiation Physics Phase
Glossary Radiation Physics Phase space co-ordinates : (x,y,z,E,θ,φ), where (x,y,z) are the Cartesian coordinates of the point in configuration space where the field is evaluated, E is the particle (generically including photons) energy, and (θ,φ) are the spherical polar coordinates describing the particle direction of motion. Condensed form of phase space coordinates: (r,E) where r'xLx%yLy%zLz and E=EΩ. The vector Ω'sinθcosφLx%sinθsinφLy%cosθLz , and is a unit vector pointing in the direction of the particle velocity. Phase space volume element: d 3rd 3E'd 3rdEdΩ'dxdydzdEsinθdθdφ (cm 3&MeV&Sr) Total number of particles or photons at time t: N(t) Angular number density spectrum: d 6N n˜(r,E,t)' (cm &3&Mev &1&Sr &1) d 3rd 3E Number density spectrum: n(r,E,t)' n˜(r,E,t)dΩ m 4π Angular fluence rate spectrum: d 6N n˜ (r,E,t)'n˜(r,E,t)v' (cm &2&MeV &1&Sr &1&s &1) 3 dAzd Edt 3 where (d r'dAzvdt) Also known as angular flux density spectrum. Fluence rate spectrum: d 4N n(r,E,t)' n˜ (r,E,t)dΩ' (cm &2&MeV &1&s &1) m dAdEdt 4π Where dA is the cross sectional area of sphere centered at r Vector Fluence rate spectrum or current density: J(r,E,t)' n˜ (r,E,t)ΩdΩ (cm &2&MeV &1&s &1) m 4π d 4N J(r,E,t)@ν' Where dA is an elemental area with normal ν dAdEdt Angular fluence spectrum: t Φ˜ (r,E)' φ˜(r,E,tN)dtN (cm &2&MeV &1&Sr &1) m 0 Where t is the total exposure duration Fluence Spectrum: Φ(r,E)' Φ˜ (r,E)dΩ (cm &2&MeV &1) m 4π Energy flow vector: g(r,t)' φ˜(r,E,t)Ed 3E (MeV&cm &2&s &1) m Spectral radiance: The radiant flux per unit cross sectional area per unit solid angle per unit wave length 6 d R &2 &1 &1 Lλ(r,Ω,λ,t)' (W&m Sr nm ) dAzdΩdλ Spectral irradiance: The radiant flux per unit surface area per unit wavelength: E (r,λ,t)' L (r,Ω,λ,t)cosθdΩ (W&m &2nm &1) λ m λ Linear attenuation coefficient: The probability per unit particle path length for an interaction with the medium in which it is propagating.
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