A space fiber-optic X-ray burst detector

Describes a novel, lightweight X-ray burst detector that can be embedded in a satellite structure, thus forming a “smart skin,” which has minimal impact on the host satellite. The design is based on two types of optical fibers coupled to photodiodes. The first is a scintillating fiber, which gives a fast signal for timing. The second is a germanium-doped silica fiber, which darkens for a few milliseconds when irradiated with a burst of X-rays. The resulting slow signal is used to discriminate against electrostatic discharges. The coincidence of a fast signal from the scintillating fiber with a slow signal from the darkening fiber is the signature of an X-ray burst. The response is linear at low doses and becomes nonlinear at high doses. The authors have two techniques to test the instrument in a space experiment scheduled for 1994. First, a small, space-qualified flash X-ray unit can illuminate the fibers. Second, the authors can detect space background radiation. The cumulative dose will be monitored by RADFET dosimeters. Future work on embedding the fibers and the electronics as application specific integrated circuits (ASICs) in the spacecraft skin could lead to the use of these detectors on many satellites