Properties of ZnS(Ag)

Density [g/cm3]	4.09
Cleavage plane	polycrystalline
Wavelength of emission maximum [nm]	450
Lower wavelength cutoff [nm]	330
Refractive index at emission maximum	2.36
Photoelectron yield [% of NaI(Tl)] (for y-rays)	25 - 30

General description

Silver-activated zinc sulfide is one of the older inorganic scintillators. It has a very high scintillation efficiency comparable to that of NaI(Tl) but is only available as a polycrystalline powder. As a result, its use is limited to thin screens used primarily for a-particles or other heavy ion detection.

Thicknesses greater than about 25 mg/cm² become unusable because of the opacity of the multicrystalline layer to its own luminescence. ZnS(Ag) has a maximum in the scintillation emission spectrum at 450 nm.

The light conversion efficiency is relatively poor for fast electrons which may be an advantage when detecting heavy ionizing particles in a relatively intense y-ray background. Scintillation decay times between several hundreds of ns and 10 ms are reported and phosphorescence of still longer duration has been noted. The main application of ZnS(Ag) is in a-particle monitors.

Aside from ZnS(Ag), other scintillating powders with different properties can be used in screens for the detection of charged particles. Examples are ZnCdS(Ag) and materials such as Gd₂0₂S or Y₂0₂S doped with Tb or Eu.

[ Scintillator options available ]