Thickness Measurements of Thin CsI(Tl) Scintillators

A γ-activation method for measuring the thickness of thin CsI(Tl) polycrystalline films deposited by evaporation on large-area (∼150 cm2) backings is described. Scintillators specially prepared to be used in the FASA installation as detectors of intermediate-mass fragment multiplicity were measured. It was shown that the distribution of the film thickness along the scintillator surface can be determined by β-activity scanning. It has been shown that the film thickness decreases from the middle of the backing to its periphery by ≈25% for scintillators with a linear size of 140 mm.