Study of the Scintillation Process

A phenomenological time-dependent relation between phosphor concentration and emission intensity, including effects of self-absorption, is derived for scintillation solutions. The dependence of the integrated intensity equation on concentration of phosphor and quencher is tested experimentally in several ways using α irradiation, and found to give agreement within the (occasionally large) experimental error. Application of this equation to measurements of the decline in scintillation efficiency of anthracene crystals on bombardment with α particles suggests a method of obtaining the effective exciton ``range,'' for which we estimate ∼3000 A as a lower limit. The question of the mechanism of energy transfer is discussed, and some photographic data are presented which indicate that the large (∼1 mm) transfer distances previously observed by Ageno et al. in similar experiments may have been due to phosphor photon absorption and reemission.