Author/Authors :
Chen، نويسنده , , Y.K. and Cooper، نويسنده , , M.D. and Cooper، نويسنده , , P.S. and Dzemidzic، نويسنده , , M. and Gagliardi، نويسنده , , C.A. and Hogan، نويسنده , , G.E. and Hungerford، نويسنده , , E.V. and Kim، نويسنده , , G.J. and Knott، نويسنده , , J.E. and Lan، نويسنده , , K.J. and LIU، نويسنده , , F. and Mayes، نويسنده , , B.W. and Mischke، نويسنده , , R.E. and Phelps، نويسنده , , Nadia R. and Pinsky، نويسنده , , L.S. and Stantz، نويسنده , , K، نويسنده ,
Abstract :
The trigger for the MEGA detector system is based on signals from single, high-energy photons interacting in one of the three MEGA pair spectrometers. The trigger is divided into a fast and a slow stage. The first stage produces a fast output if a specific pattern of detector hits is observed in the scintillators and high-speed wire chambers of a pair spectrometer. The second, slow-stage interrogates drift chamber hit patterns and provides a veto when the pattern fails a minimal requirement for reconstruction of the hits into a pair of circular orbits. The trigger interacts with the photon detector electronics by gating limited sections of the detector during the read-out of an event. This paper describes the two stage trigger system, the photon detector electronics, and the implementation of the trigger outputs to strobe the data acquisition system. The performance of the trigger is compared to Monte Carlo simulations of the photon detector response.
