Background rejection techniques in CCD X-ray detectors for astronomy

A number of different charge-coupled devices (CCDs) have been exposed to gamma and beta sources in order to simulate the charged-particle background response of spaceborne X-ray astronomy detectors. Two rejection techniques have been investigated: energy veto and pixel-to-pixel anticoincidence. In the most favorable conditions, a rejection of >99.9% has been obtained. The latter selection criterion can be used to reject X-ray data in which the event charge is incompletely collected. Improved X-ray energy resolution is obtained, and an upper limit to the Fano factor in silicon is measured. A novel technique for minimizing systematic errors in the X-ray-energy-to-charge-conversion factor is described.<>