SEMI-INTELLIGENT TRIGGER-GENERATION SCHEME FOR CHERENKOV LIGHT IMAGING CAMERAS

We propose here an improved trigger-generation scheme for TeV gamma-ra y imaging telescopes. Based on a memory-based Majority Coincidence Cir cuit, this scheme involves deriving two- or three-pixel nearest-neighb our coincidences as against the conventional approach of generating pr ompt coincidences using any two photomultiplier detector pixels of an imaging-camera. As such, the new method can discriminate better agains t shot-noise-generated triggers and, to a significant extent, also aga inst cosmic-ray and local-muon-generated background events, without co mpromising on the telescope response to events of gamma-ray origin. An optional feature of the proposed scheme is that a suitably scaled-up value of the chance-trigger rate can be independently derived, thereby making it possible to use this parameter reliably for keeping a log o f the ''health'' of the experimental system.