An alpha tagged X-ray source for the calibration of space borne X-ray detectors

Calibration of X-ray detectors is very important to understand the performance characteristics of the detectors and their variation with time and changing operational conditions. This enables the most accurate translation of the measurements to absolute and relative values of the incident X-ray photon energy so that physical models of the source emission can be tested. It is a general practice to put a known X-ray source (radio active source) in the detector housing for the calibration purpose. This, however, increases the background. Tagging the calibration source with the signal from a simultaneously emitted charge particle (like alpha particle) can identify the X-ray event used for calibration. Here in this paper, we present a new design for an alpha-tagged X-ray source using Am 241 radio active source and describe its performance characteristics. Its application for the upcoming Astrosat satellite is also discussed.