Author/Authors :
Bernet، نويسنده , , C. and Bravar، نويسنده , , A. and Hannappel، نويسنده , , J. and Harrach، نويسنده , , D.v. and Hermann، نويسنده , , R. and Kabuك، نويسنده , , E. and Klein، نويسنده , , F. and Korzenev، نويسنده , , A. and Leberig، نويسنده , , M. and Ostrick، نويسنده , , M. and Pretz، نويسنده , , J. and Windmolders، نويسنده , , R. and Zhao، نويسنده , , J.، نويسنده ,
Abstract :
The trigger system of the COMPASS experiment at the CERN polarized muon beam is presented. It detects muon scattering events on (polarized) nucleons with a relative energy loss exceeding a selectable value y min independent of the four-momentum transfer. The requirement of a minimum energy deposit in a hadron calorimeter rejects background events like scattering on electrons, elastic and quasi-elastic radiative events as well as events from beam halo tracks. The trigger system which can be considered as a tagger for quasi-real photon events is now, along with larger trigger hodoscope system for deep inelastic scattering events, in regular use for the measurement of the gluon polarisation Δ G / G .
Keywords :
trigger , Muon beam , Scintillators , Calorimeter , COMPASS spectrometer , Polarised deep inelastic lepton scattering
