Freiburg 2008 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 74: Gammaastronomie III
T 74.3: Vortrag
Mittwoch, 5. März 2008, 17:15–17:30, KGII-HS 2006
An analog sum trigger for Cherenkov Telescopes for low energy thresholds: Concept and realization — •Thomas Schweizer1, Adam Nepomuk Otte2, Michael Rissi3, Maxim Shayduk2, Eckart Lorenz1, Razmik Mirzoyan1, and Masahiro Teshima1 for the MAGIC collaboration — 1Max Plank institute, Muenchen — 2Humboldt Universitaet, Berlin — 3ETH Zurich
A new analog trigger concept which allows to reduce significantly the energy threshold of Cherenkov telescopes has been designed and implemented for the MAGIC telescope. The analog signals of a patch in the camera consisting of 10-18 pixels are summed up in an analog way. In order to prevent triggers from PMT-afterpulses and noise the signals are clipped at a certain amplitude. The average cosmic ray induced signals of MAGIC are 2.6ns FWHM. This allows us to keep the coincidence time window very short and strongly suppress accidental triggers from night sky background (NSB). Also, unlike the usual digital trigger designs, all low photon signals in the given patch in the camera are summed up and contribute into the trigger. As a result one can significantly lower the threshold setting. This trigger concept provides a low cost trigger installation and very effective and stable trigger for Cherenkov telescopes.