Analytic representation of bremsstrahlung spectra from thick radiators as a function of photon energy and angle
A convenient, analytic representation of the bremsstrahlung spectrum as a function of both photon energy and angle has been developed. The representation accommodates radiators of thicknesses up to the range of the incident electrons, and is primarily intended for electrons in the energy range ∼ 5-20 MeV. The basis is a linear integrated-over-angle intensity spectrum, a Gaussian bremsstrahlung cross section angular distribution, a Gaussian electron multiple scattering angular distribution, a constant electron stopping power, and a linear function representing both photon attenuation within the radiator and the electron transmission function through the radiator, from which is derived an analytic expression involving the exponential integral ei( x). On comparing with measurements and Monte Carlo computations, the present expression is found to deviate by ∼ 20%.