Scintillations from Organic Crystals: Specific Fluorescence and Relative Response to Different Radiations

The scintillation response S of organic crystals depends on the nature and energy E of the incident ionizing particle, of residual range r. The specific fluorescence dS/dr is not in general proportional to the specific energy loss dE/dr. By considering the quenching effect of the molecules damaged by the particle on the `excitons' produced by it, it is shown that dS/dr = (A dE/dr)/(1 + kB dE/dr). A and kB are constants, which have been evaluated for anthracene from observations of S and E, and the range-energy data. Curves are computed for the relative response S of anthracene to electrons, protons, deuterons and α-particles of E up to 15 MeV, and these are shown to agree closely with the available experimental results. The method used for evaluating the relative response is applicable to ionizing particles of any nature or energy, and also to the other organic scintillation crystals