Correct method for energy resolution and instrumental function calculation for scintillation spectrometers

An approach is described and formulae are derived for calculating instrumental functions and energy resolution of a scintillation spectrometer with several photomultipliers when taking account of multiple particle scattering in a crystal. According to the approach the photoelectron distribution on the first dynode of a photoelectron multiplier is simulated and then absorbed energy spectrum is checked against the Gauss distribution. A correct expression for amplitude distribution at the spectrometer output is derived