Microsecond Measurement of the Phosphorescence of X-Ray Fluorescent Screens

Abstract

Microsecond square‐wave x‐ray pulses, repeated a thousand times a second, were obtained by operating an x‐ray tube directly from a radar pulser. The phosphorescent build‐up and decay of light emitted by fluorescent materials when irradiated by the x‐ray pulses was observed with a multiplier phototube connected to an oscilloscope. Oscillograms of CaWO₄ (radiographic intensifying screen) and BaSO₄ indicate simple exponential response, with decay to 1/eth intensity in 6 and 0.8 microseconds, respectively. MgWO₄ and Patterson B (fluoroscopic) and D (photofluorographic) screens were found to complete their main response to microsecond excitation in 10 to 100 microseconds, but their decay is not exponential.