The NA60 experiment readout architecture

The NA60 experiment was designed to identify signatures of a new state of matter, the Quark Gluon Plasma, in heavy-ion collisions at the CERN Super Proton Synchroton. The apparatus is composed of four main detectors: a muon spectrometer (MS), a zero degree calorimeter (ZDC), a silicon vertex telescope (VT), and a silicon microstrip beam tracker (BT). The readout of the whole experiment is based on a PCI architecture. The basic unit is a general purpose PCI card, interfaced to the different subdetectors via custom mezzanine cards. This allowed us to successfully implement several completely different readout protocols (from the VME like protocol of the MS to the custom protocol of the pixel telescope). The system was fully tested with proton and ion beams, and several million events were collected in 2002 and 2003. This paper presents the readout architecture of NA60, with particular emphasis on the PCI layer common to all the subdetectors.