280 research outputs found

    PCI Based Read-out Receiver Card in the ALICE DAQ System

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    The Detector Data Link (DDL) is the high-speed optical link for the ALICE experiment. This link shall transfer the data coming from the detectors at 100 MB/s rate. The main components of the link have been developed: the destination Interface Unit (DIU), the Source Interface Unit (SIU) and the Read-out Receiver Card (RORC). The first RORC version is based on the VME bus. The performance tests show that the maximum VME bandwidth could be reached. Meanwhile the PCI bus became very popular and is used in many platforms. The development of a PCI-based version has been started. The document describes the prototype version in three sections. An overview explains the main purpose of the card: to provide an interface between the DDL and the PCI bus. Acting as a 32bit/33MHz PCI master the card is able to write or read directly to or from the system memory from or to the DDL, respectively. Beside these functions the card can also be used as an autonomous data generator. The card has been designed to be well adapted to applications, which require small software overhead such the high-speed data acquisition systems. The implementation of the firmware will be presented. For the logic design we are using VHDL and schematic draw. Software library routines were written in C and are available on Linux OS. The results of performance measurements will be available to allow the comparison between the VME-RORC and PCI-RORC. In the conclusion the future plans and the idea of the improved (64bit/66MHz) PCI-RORC will be shown

    New results from the NA57 experiment

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    We report results from the experiment NA57 at CERN SPS on hyperon production at midrapidity in Pb-Pb collisions at 158 AA GeV/cc and 40 AA GeV/cc. Λ\Lambda, Ξ\Xi and Ω\Omega yields are compared with those from the STAR experiment at the higher energy of the BNL RHIC. Λ\Lambda, Ξ\Xi, Ω\Omega\ and preliminary KS0K_S^0 transverse mass spectra are presented and interpreted within the framework of a hydro-dynamical blast wave model.Comment: 8 pages, 3 figures, contribution to the proceedings of The XXXVIIIth Rencontres de Moriond "QCD and High Energy Hadronic Interactions

    Study of the transverse mass spectra of strange particles in Pb-Pb collisions at 158 A GeV/c

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    The NA57 experiment has collected high statistics, high purity samples of \PKzS and \PgL, Ξ\Xi and Ω\Omega hyperons produced in Pb-Pb collisions at 158 AA GeV/cc. In this paper we present a study of the transverse mass spectra of these particles for a sample of events corresponding to the most central 53% of the inelastic Pb-Pb cross-section. We analyse the transverse mass distributions in the framework of the blast-wave model for the full sample and, for the first time at the SPS, as a function of the event centrality.Comment: 22 pages, 14 figures, submitted to J. Phys. G: Nucl. Phy

    Expansion dynamics of Pb-Pb collisions at 40 A GeV/c viewed by negatively charged hadrons

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    In this paper we present results on transverse mass spectra and Hanbury-Brown and Twiss correlation functions of negatively charged hadrons, which are expected to be mostly negative pions, measured in Pb-Pb collisions at 40 A GeV/c beam momentum. Based on these data, the collision dynamics and the space-time extent of the system at the thermal freeze-out are studied over a centrality range corresponding to the most central 53% of the Pb--Pb inelastic cross section. Comparisons with freeze-out conditions of strange particles and HBT results from other experiments are discussed.Comment: 29 pages, 18 figure
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