Technological developments toward the small size telescopes of the Cherenkov Telescope Array

Abstract

In the last two decades a new window for ground-based high energy astrophysics has been opened. This explores the energy band from about 100 GeV to 10 TeV by making use of Imaging Atmospheric Cherenkov Telescopes (IACTs). Research in Very High Energy (VHE) gamma-ray astronomy is progressing rapidly and, thanks to the newest facilities such as MAGIC, HESS and VERITAS, astronomers and particle physicists are obtaining data with far-reaching implications for theoretical models. The Cherenkov Telescope Array (CTA) is the ambitious international next-generation facility for gamma-ray astronomy and astrophysics that aims to provide a sensitivity of a factor of 10 higher than current instruments, extend the energy band coverage from below 50 GeV to above 100 TeV, and improve significantly the energy and angular resolution to allow precise imaging, photometry and spectroscopy of sources. To achieve this, an extended array composed of nearly 100 telescopes of large, medium and small dimensions is under development. Those telescopes will be optimized to cover the low, intermediate and high energy regimes, respectively. In this paper, we focus our attention on the Small Size Telescopes (SSTs): these will be installed on the CTA southern hemisphere site and will cover an area of up to 10 km 2 . The energy range over which the SSTs will be sensitive is from around 1 TeV to several hundreds of TeV. The status of the optical and mechanical designs of these telescopes is presented and discussed. Comments are also made on the focal surface instruments under development for the SSTs.