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
  We suggest a new approach to study the cosmis ray (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 atmospheric Cherenkov telescopes (IACTs) of a special architecture. This array consists of telescopes with a relatively small mirror size (~10 square meters) separated from each other by large distances (~500 meters) and equipped by multichannel cameras with a modest pixel size (0.3-0.5 degree) and a sufficiently large viewing angle (6-7 degree).   Compared to traditional IACT systems (like HEGRA, HESS or VERITAS) the IACT array considered here could provide a very large detection area (several square kilometers 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. 
F.A.Aharonian, V.V.Bugayov, J.Kettler, A.V.Plyasheshnikov, H.J.Voelk