"Linear Attenuation Coefficient"@en . "http://en.wikipedia.org/wiki/Attenuation_coefficient"^^ . . "\\(\\mu = -\\frac{1}{J}\\frac{dJ}{dx}\\), where \\(J\\) is the magnitude of the current rate of a beam of particles parallel to the \\(x-direction\\).\n\nOr:\n\n\\(\\mu(\\lambda) = \\frac{1}{\\Phi_\\lambda(\\lambda)}\\frac{d\\Phi_\\lambda(\\lambda)}{dl}\\), where \\(\\frac{d\\Phi}{\\Phi}\\) is the relative decrease in the spectral radiant flux \\(\\Phi\\) of a collimated beam of electromagnetic radiation corresponding to the wavelength \\(\\lambda\\) during traversal of an infinitesimal layer of a medium and \\(dl\\) is the length traversed."^^ . . "\\(\\mu\\)"^^ . . . . . . "\"Linear Attenuation Coefficient\", also called the attenuation coefficient, narrow beam attenuation coefficient, or absorption coefficient, is a quantity that characterizes how easily a material or medium can be penetrated by a beam of light, sound, particles, or other energy or matter." . "http://www.iso.org/iso/catalogue_detail?csnumber=31895"^^ . . . .