An investigation on the characteristics of `pure´ CsI crystals

Over 20 small crystals of undoped CsI, referred to as CsI (pure), have been grown and evaluated for optical and scintillation performance. Some of these crystals exhibit a single emission band, while other crystals exhibit more than one emission band, occurring in the region from 300 nm to 600 nm. The emission spectra are compared. The gamma ray scintillation efficiency varies by about -0.6%/°C for crystals having only one emission band at 315 nm from 25 to 120°C. The material is linear for gamma rays from 0.06 to 2.6 MeV. The stability of the heat-induced emission band over a function of time is measured. CsI (pure) scintillation performance is compared to that of NaI(Tl), BaF₂, Bi₄Ge₃O₁₂, and CsF