Optical design study, testing and qualification of a Schwarzschild-Couder telescope for CTA and an assessment on the Intensity Interferometry capabilities with CTA

There is a growing common effort in the very high energy community towards the development of new research infrastructures to answer the fundamental questions of modern high-energy astrophysics and astroparticle physics. The Cherenkov Telescope Array Observatory (CTAO) is an international project aiming to deploy two separate arrays to observe the whole VHE sky between E = 20 GeV up to E = 300 TeV in a long term plan of about 30 years of operations. CTA is designed to increase the sensitivity by a factor 10 at 1 TeV, to enlarge the detection area, the angular resolution and the field of view over the facilities operating today. The observatory will be characterized by high flexibility, enhanced monitoring and deep survey capabilities, short time scale and simultaneous observations in multiple fields. This PhD thesis addresses the optical design study and testing of dual mirror Imaging Atmospheric Cherenkov Telescopes (IACTs) for the incoming CTAO. All of the IACTs facilities currently operating rely on single mirror solutions, which are mostly parabolic or Davies-Cotton optical designs, however there is a novel interest in the development of dual mirror configurations following the Schwarzschild-Couder optical design. This peculiar design, based on two highly aspherical mirrors promises wide-field, aplanatic telescopes characterized by small f-numbers and more compact structures. Dual mirror solutions allow use smaller camera pixels (3-6 mm) based on Silicon Photo Multiplier technology in substitution of the larger Photo Multiplier Tubes (1 inch) currently in use. The increased complexity in terms of optics manufacturing, replication and alignment is motivated from the attractive new capabilities of such configuration. In this context the Italian National Institute for Astrophysics (INAF) supported by the Italian Ministry of Education, University and Research (MIUR), is developing a small sized telescope prototype for CTA, named ASTRI, which is based upon the Schwar