Experimental manifestations of CsI:Na crystal hygroscopicity

Abstract

Hygroscopicity of CsI:Na crystal has a focal nature and can be observed visually but at specific conditions. Formation of liquid puddles on the boundary crystal–air course a negative change in surface relief. Further transformation of NaI to NaHCO3 and water puddles to a loose coating course a change in reflectivity, its uniformity and in energy resolution. To prevent these negative changes it is sufficient to wipe the crystal surface dry before removing of scintillator from dry room. Another way is consisted in application of hydrophobic protective coating on the crystal surfaces