Cherenkov Telescope Arrays

Michael Daniel, Durham University

The Earth's atmosphere is opaque to high energy photons, but the
effects of their atmospheric absorption are detectable at ground level
through the emission of secondary Cherenkov light. The flash of
Cherenkov light produced is very faint, but through the use of large
light collectors and fast electronics it can be picked out from the
background. Stereoscopic arrays of these Imaging Atmospheric Cherenkov
Telescopes (IACTs) have proven extremely successful in bringing the
field of VHE astronomy to maturity. The next generation Cherenkov
Telescope Array (CTA) aims to increase sensitivity by an order of
magnitude over current experiments by building an array of a few tens of
telescopes with baselines ranging from 50m up to a kilometre. This talk
will summarise the atmospheric Cherenkov technique, the instruments used
in exploiting it and the design work going into CTA.