Small-size pulsed X-ray source for measurements of scintillator decay time constants

Summary form only given. The main scintillator characteristics such decay time, light output, emission spectrum, are usually measured at excitation by gamma quanta or particles (electrons, protons, neutrons). Rather recently, subnanosecond X-ray pulses have been used for study of scintillators. In this work, we describe the small-size short-pulsed X-ray source. The basic elements of the source are three-electrode X-ray tube, which operates at 30 kV, 0.5 A, and fast GaAs modulator coaxial matched with grid electrode of the tube. The source has the following limiting parameters pulse duration /spl sim/0.5 ns, pulse frequency 100 kHz, required power /spl sim/50 W. The source is constructed in form of cylinder with 15 cm length and 10 cm diameter (together with lead radiation protection). Such system, like PMT, is easily matched with cryostat. The advantages of the tube with thermocathode over light-excited X-ray tube is higher anode current (0.5 A compared with 50 mA in last case) and lower cost. The decay curve of conventional scintillator BaF/sub 2/ with fast (0.88/spl plusmn/0.02 ns) and slow (850/spl plusmn/5 ms) components was measured to illustrate the capabilities of the set-up. Some traditional and new scintillating materials have been also investigated.