The readout system for the ALICE Zero Degree Calorimeters

ALICE (A Large Ion Collider Experiment) at the CERN LHC will investigate the physics of strongly interacting matter at extreme energy densities where the formation of the Quark Gluon Plasma is expected. Its properties can be studied from observations like the production of mesons with charm and beauty quarks. These observations have to be studied as a function of energy density which is determined by the centrality of collisions. The energy carried by the spectator nucleons, related to the centrality, is measured by the Zero Degree Calorimeters (ZDC). The ZDC readout consists of a VME system with a ZDC readout card (ZRC), a VME Processor, Discriminators, a ZDC Trigger Card (ZTC), scalers, QDCs and TDCs. The system was successfully tested during the 2009 data taking and is currently operational at the LHC. This paper describes the readout system of the ZDC.