Readout upgrade, hardware and software, for the ALICE Data Acquisition program

Abstract ALICE [experiment web site, May 10, 2009 〈 http://public.web.cern.ch/public/en/LHC/ALICEen.html 〉 ] (A Large Ion Collider Experiment) is an experiment at the LHC (Large Hadron Collider) optimized for the study of heavy-ion collisions. The main aim of the experiment is to study the behavior of strongly interaction matter and quark gluon plasma. The ALICE DAQ (Data Acquisition) system has been deployed and used intensively during the commissioning of the experiment. This paper will present the evolution of one particular area of the system: the detector readout. The data produced by each detector are received by DATE [ALICE data acquisition web site, May 10, 2009 〈 http://phdepaid.web.cern.ch/phdepaid/ 〉 ] (ALICE Data Acquisition program) using PCI (Peripheral Component Interconnect) based card called D-RORC [web site, May 10, 2009 〈 http://alice-proj-ddl.web.cern.ch/alice-proj-ddl/rorc_intro.html 〉 ] (DAQ Readout Receiver Card). Of the order of 400 of these cards are installed in the PCs of the DAQ farm, and they are connected by optical links called DDL [web site, May 10, 2009 〈 http://alice-proj-ddl.web.cern.ch/alice-proj-ddl/ddl_intro.html 〉 ] (Detector Data Link) to the detector readout electronics. The D-RORC is controlled by the readout software, part of the DATE program that reads the events coming from these cards. We will present the results obtained during the performance tests of the new release of the D-RORC, PCI Express, in development at CERN. The paper will review the working principles of the D-RORC, its use by the readout software and the benefits in using PCI Express instead PCI-X. It will also introduce the work in progress for the new release of the readout software towards the next hardware platform based on 64-bit computer architecture and DDLs based on 10G Ethernet.