Undoped cesium iodide or CsI(pure) has high density, sufficiently small radiation length (1,86 sm) and much lower hygroscopicity than CsI(Tl). CsI(pure) has fluorescence spectrum with maximum at 315 nm with the short decay time (about 16 ns) and long-wave component which allows effectively using this scintillation material for medium- and high-energy physics experiments. Therefore, CsI(pure) can be used when high counting rate is required. CsI(pure) differs from CsI(Tl) and CsI(Na) scintillators by a much faster response and lower light yield.
Undoped CsI has higher radiation stability than when doped with thallium or sodium, and its properties can be largely restored after а certain time. No substantial radiation damage was observed in CsI up to doses of 105 rad.