ABSTRACT
This chapter considers the techniques and technologies used in astronomical instruments. Because the Earth’s atmosphere is completely opaque to X and γ radiation, it is normally only possible to carry out observations from high-altitude balloons or better from space. The signatures of very high-energy γ rays and cosmic ray particles can be observed from the ground through their interactions with the atmosphere leading to showers of particles and radiation, which can reach ground-based detectors. The performance of charge coupled device arrays in space can be adversely affected by damage to the crystal structure caused by ionising particle hits, especially high-energy protons. The proportional counter uses gas to absorb the incoming X-ray photon, producing a degree of ionisation proportional to its energy. A scintillation detector uses a material, which has luminescent centres. The conversion of γ-ray energy to electrical signal in a scintillation detection system involves several stages.
