Shape distortion of 128I ß −spectrum observed by a self-activated CsI(Tl) scintillator for high-sensitivity neutron measurements

In addition to the factors mentioned above, the efficiency of scintillation light collection by the photodetectors also affects the shape distortion of the ß− spectrum slightly through spectral line broadening due to the degradation of the energy resolution. This effect was estimated using a simple model with different discrimination settings for ß− pulse counting.