Aluminum-based segmented mirrors for gamma-ray Cherenkov Telescopes via replication: status and perspectives

Current generation Imaging Atmospheric Cherenkov Telescopes (IACTs) like HESS, MAGIC and VERITAS, operated in array-mode, have opened a new astronomical window in high energy gamma-ray band from a few tens GeV to a hundred TeV, allowing to observe the most energetic phenomena on going in our Universe. New generation arrays like ASTRI, with its 9 small-class telescopes operated at Tenerife, Canary Islands, and the very ambitious Cherenkov Telescope Array Observatory (CTAO - with its two sites at the northern and southern hemispheres and about 70 telescopes of different classes) will need to fabricate a few thousand square meters of reflective segments of about 1 m2 area and different shapes for making the primary mirrors. Different low-cost technologies have been used so far, like the direct figuring and polishing of glass slabs, the diamond turning of pre-formed aluminum sandwiched panels and the replica of thin glass foils for making composite sandwiched mirrors. In this paper we will present a further alternative solution, based on the replica of aluminum foils - precoated with a high reflectivity and durability multilayer film - for making sandwiched mirrors. This approach will simplify a lot the production chain, allowing us to make low-cost panels entirely made of aluminum. The method of production of the aluminum replicated panels is discussed and the preliminary performance results obtained with a prototype mirror presented.