X-ray Detectors for Astrophysics

Astrophysical observations in the X-ray band require the detection of the photons in combination with an imaging system. This imaging system can vary from focusing mirrors characterized by their effective area and angular resolution to a simple collimated system where photons from a small solid angle on the sky are selected. An overview of these optical systems is given in Section 1 of this handbook (Part II, “Optics for X-Ray Astrophysics”). In this section, we give an introduction to X-ray detectors ranging from the soft to the X-rays, corresponding to 0.1 to 100 keV (or 124 Å to 0.124 Å). As an introduction to this section, we describe in this paper the basic physical processes on which the detection of photons is based and give an overview of the relevant detector classes and their actual use in space missions. It should also be noted that some of the detectors are used in other fields, including medicine and material science, but we will not address this.