CDC Trigger System

The CDC trigger is one of the key elements of the Belle trigger system. It is required to be fully efficient for tracks originating from the interaction point and relatively insensitive to background tracks from other sources. CDC provides two types of triggers: the $r$-$\phi$ trigger based on signals from axial super-layers and the $z$-trigger which is formed from the direct z information provided by the cathode strips and z coordinates inferred from the axial and stereo super-layers.