Radiation tolerance and afterglow of CsI:Tl crystals codoped with NO2− ions

This paper discusses the radiation tolerance, afterglow, and IR absorption spectra of CsI:Tl crystals grown with an addition of the salt NaNO3. Crystals 250mm in diameter and 360mm high are grown by a modified Kyropoulos method with replenishment of the melt, using a special crucible-feeder design. It is shown that adding 0.5 mass% NaNO3 to the feeder makes it possible to obtain crystals whose IR spectra includes an absorption band not of nitrate but of nitrite ions. The resulting crystals possess low afterglow (a factor of two less than with CsI:Tl) and maintain radiation tolerance to a dose of at least 103Gy, and this increases the possibilities of using them in practice.