Vacuum ultraviolet and x-ray luminescence efficiencies of Y₃Al₅O₁₂:Ce phosphor screens

Phosphor screens are used in many applications to convert incident radiation to visible wavelengths that can be readily measured by modern detectors. For many such systems it is necessary to tailor the phosphor screen thickness to the wavelength range of interest in order to maximize the efficiency. Here, we describe the experiments made to determine the luminescent efficiency of thin Y₃Al₅O₁₂:Ce (P-46) phosphor screens (1–22 mg cm^-2) in the vacuum ultraviolet and x-ray ranges. We use current and previous measurements to obtain fitting parameters for a granular unidimensional radiation transfer model developed. In the model, we take into account the effects of scattering and absorption of the luminescent light emitted and we discuss the effects of grain size and shape on the model. Finally, we find that a screen thickness of ∼1.7 mg cm^-2 is optimum for incident radiation between 1.2 and 124 nm but this thickness becomes wavelength dependent at shorter wavelengths (0.025–1.2 nm). © 1999 American Institute of Physics.