On the potential of the imaging atmospheric Cherenkov technique for study of the mass composition of primary cosmic radiation in the energy region above 30 TeV

Abstract The technique of imaging atmospheric Cherenkov telescopes (IACTs) has proved to be an effective tool to register cosmic γ-rays in the very high energy region. The high detection rate of the IACT technique and its capability to reconstruct accurately the air shower parameters make it attractive to use this technique for the study of the mass composition of cosmic rays (CRs). In this article we suggest a new approach to study the CR mass composition in the energy region from 30 TeV/nucleus up to the “knee” region, i.e. up to a few PeV/nucleus, using an array of imaging telescopes of a special architecture. This array consists of telescopes with a relatively small mirror size (∼10 m 2 ) separated from each other by large distances (∼500 m) and equipped by multi-channel cameras with a modest pixel size (0.3–0.5°) and a sufficiently large viewing angle (6–7°). Compared to traditional IACT systems (like HEGRA, HESS or VERITAS) the IACT array considered in this study could provide a very large detection area (several km 2 or more). At the same time, it allows an accurate measurement of the energy of CR-induced air showers (the energy resolution ranges within 25–35%) and an effective separation of air showers created by different nuclei. Particularly, it is possible to enrich air showers belonging to the nucleus group assigned for selection up to ∼90% purity at a detection efficiency of 15–20% of such showers.