Telescopes for the High Energy Section of the Cherenkov Telescope Array

Abstract

The Cherenkov Telescope Array (CTA) will provide an unprecedented level of sensitivity to very-high-energy (VHE) gamma rays across an energy range from below 50 GeV to above 100 TeV. To achieve this, large, medium and small size telescopes are required, covering the low, inter mediate and high energy regimes, respectively. The small sizes telescope (SST) array will occupy an area on the ground of up to 10 km 2 and operate from around 1 TeV to several hundred TeV. It will allow CTA to probe the gamma-ray universe with the highest angular resolution yet obtained above the hard X-ray band, enabling morphological studies of PeV particle acceleration sites and discrimination between hadronic and leptonic cosmic ray acceleration models. Under consideration for the SST are a Davies-Cotton design with a mirror diameter of about 7 m and a dual mirror telescope with primary mirror diameter of about 4 m. The status of the optical and mechanical designs of each of these alternatives are presented and the pros and cons of each approach discussed. Comments are also made on the cameras needed for each of these instruments.