Wide field-of-view atmospheric Cherenkov telescope based on refractive lens

A wide field of view (FOV) is an important feature of a detector in the gamma ray observation of sporadic, extended, and transient sources. In this work, we discuss an atmospheric Cherenkov telescope (ACT) with a refractive water convex lens as its light collector, and we test the feasibility of this new approach. We determine the optical properties of a water lens with a diameter of 0.9 m, such as focal length, spot size, and transmittance. The first detection of cosmic rays (CRs) observed in coincidence with a scintillator extensive air shower (EAS) array is presented and discussed.