Single photon counting approach for imaging atmospheric Cherenkov telescopes

The aim of this article is to present a single photon counting technique applied to the imaging atmospheric Cherenkov telescopes as an alternative to the charge integration technique used by most experiments in the field. A comparison of the two techniques has been performed, assuming suitable and realistic telescope layouts but different methods to treat and convert the electrical signals at the output of the light sensors. A set of γ-ray induced showers, with primary energies ranging from 300 GeV to 10 TeV, has been simulated for this comparison. The study has been performed both for a single telescope and for a three-telescope array. The results show, in both cases, considerably higher trigger efficiencies in the single photon counting method, with respect to the analog one, particularly at the lowest energies. Single telescope energy thresholds for the two methods are also reported and discussed.