A Criterion for the Mass Estimation of the Primary Particles of the Inclined Showers in SPHERE-2 Experiment

A new method for the separation of inclined extensive air showers (EAS) according to the their primary particle masses is considered based on the directly measurable characteristics of the lateral distribution (LD) of Cherenkov light (CL) and enabling to attribute the showers to one of the three mass groups in the event-by-event approach in the primary energy range & 10^16 eV. The method is destined for the processing of the inclined EAS events detected by SPHERE-2 experiment. Quantitative characteristics of the universal selection criterion are specified, its weak dependence on the night sky background is stated. The criterion’s quality measures are to be considered as the landmarks for the future work because they are assessed for CL LD at the snowed ground level and thus do not account for the the process of the reflected CL detection by SPHERE-2 telescope. The method might be interesting for the now active and future detector arrays intended for EAS studies using CL.