Luminescence Yield in Roentgenography with High-Energy X-Rays

A universal energy transfer function is derived that applies to absorption of X-rays or gamma rays in all thin luminescent screens over a wide range of incident energies. This function is evaluated for monoenergetic incident radiation and for bremsstrahlung originating in gold targets. A scaled universal luminescence yield is given, in terms of the energy transfer function minus an energy escape function which accounts for the energy loss by electron escape from the phosphor. Under conditions where the energy escape is small, the dominant dependence of the luminescence yield on the phosphor appears only as a multiplicative material characteristic constant.