Enhancement of the Yakutsk array by atmospheric Cherenkov telescopes to study cosmic rays above 1015 eV

The aim of the Yakutsk array enhancement project is to create an instrument to study the highest-energy galactic cosmic rays (CRs) - their sources, energy spectrum, and mass composition. Additionally, there will be unique capabilities for investigations in the transition region between galactic and extragalactic components of CRs. Using the well-developed imaging atmospheric Cherenkov telescope technique adapted to the energy region E>1015 eV, we plan to measure the longitudinal structure parameters of the shower, e.g. angular and temporal distributions of the Cherenkov signal related to Xmax and the mass composition of CRs. The main advantages of the Yakutsk array, such as its multi-component measurements of extensive air showers, and model-independent CR energy estimation based on Cherenkov light measurements, will be inherited by the instrument to be created.