15830879
Centrality dependence of the expansion dynamics in Pb Pb collisions at 158-A-GeV/c
Two-particle correlation functions of negatively charged hadrons from Pb-Pb collisions at 158?GeV?c-1/nucleon have been measured by the WA97 experiment at the CERN SPS. A Coulomb correction procedure that assumes an expanding source has been implemented. Within the framework of an expanding thermalized source model the size and dynamical state of the collision fireball at freeze-out have been reconstructed as a function of the centrality of the collision. Less central collisions exhibit a different dynamics than central ones: both transverse and longitudinal expansion velocities are slower, the expansion duration is shorter and the system freezes out, showing smaller dimensions and higher temperature.
121444459
Heavy flavours in ALICE
The ALICE experiment, currently in the commissioning phase, will study nucleus?nucleus and proton?proton collisions at the CERN large hadron collider (LHC). We review the ALICE heavy-flavour physics program and present a selection of results on the expected performance.
7281568
New results from the NA57 experiment
The production of hyperons in Pb–Pb and p–Be interaction at 40 A GeV/c beam momentum has been measured by the NA57 experiment. Strange particle enhancements at 40 A GeV/c are presented for the first time and compared to those measured at 158 A GeV/c. The transverse mass spectra of high statistics, high purity samples of K0S, Λ, Ξ and Ω particles produced in Pb–Pb collisions at 158 A GeV/c have been studied in the framework of the blast-wave model. The dependence of the freeze-out parameters on particle species and event centrality is discussed.
119200364
NA57 main results
The CERN NA57 experiment was designed to study the production of strange and multi-strange particles in heavy-ion collisions at SPS energies; its physics programme is essentially completed. A review of the main results is presented.
118028873
Results on Lambda and Xi production in Pb-Pb collisions at 160 GeV/c per nucleon from the NA57 experiment
The NA57 experiment has been designed to study the onset of enhanced production of strange baryons and anti-baryons in Pb-Pb collisions with respect to p-Be collisions. This enhancement is considered a sensitive signature for a phase transition to a new state of matter -- the Quark Gluon Plasma (QGP). In this paper, we report results on Lambda and Xi hyperon production in central Pb-Pb collisions at 160 GeV/c per nucleon beam momentum.
119458644
Feasibility study of a XML-based software environment to manage data acquisition hardware devices
A Software environment to describe configuration, control and test systems for data acquisition hardware devices is presented. The design follows a model that enforces a comprehensive use of an extensible markup language (XML) syntax to describe both the code and associated data. A feasibility study of this software, carried out for the CMS experiment at CERN, is also presented. This is based on a number of standalone applications for different hardware modules, and the design of a hardware management system to remotely access to these heterogeneous subsystems through a uniform web service interface.
15045293
The bakelite for the RPCs of the experiment CMS
Results from aging tests on the bakelite used for the CMS RPCs are presented. Samples of melaminic bakelite were exposed to a heavy gamma and neutron radiation. Data on the bulk resistivity were collected while accumulating gamma and neutron doses and particles fluence up to values well beyond those expected in 10 years of RPCs operation in the barrel region of CMS. The test with gamma radiation was performed at the CERN Gamma Irradiation Facility (GIF) with a 20 Ci 137Cs source. A total absorbed dose of 5 Gy was accumulated during an irradiation period of about one month. The test with both neutron and gamma radiation was held at the Triga Mark II 250 kW reactor located in Pavia. A total of 80 h of exposure were accumulated integrating a neutron and gamma dose of about 80 Gy and a fast neutron fluence of some . Experimental data on dose rate in both the test facilities have been compared to simulation output and show a good agreement.
209834550
Measurement of the differential cross section for isolated prompt photon production in pp collisions at 7 TeV
A measurement of the differential cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data sample corresponds to an integrated luminosity of 36 inverse picobarns recorded by the CMS detector at the LHC. The measurement covers the pseudorapidity range |eta|<2.5 and the transverse energy range 25 < ET < 400 GeV, corresponding to the kinematic region 0.007 < xT < 0.114. Photon candidates are identified with two complementary methods, one based on photon conversions in the silicon tracker and the other on isolated energy deposits in the electromagnetic calorimeter. The measured cross section is presented as a function of ET in four pseudorapidity regions. The next-to-leading-order perturbative QCD calculations are consistent with the measured cross section.
120807924
Results from a complete simulation study of the RPC based muon trigger system for the CMS experiment
The performance of the Resistive Plate Chambers-based muon trigger of the CMS detector has been studied by means of a full simulation of the system under realistic operating conditions. Requirements on the performance of the chambers are deduced.
56416813
Aging study for Resistive Plate Chambers of the CMS Muon Trigger Detector
A long-term aging test of a Resistive Plate Chamber (RPC) was carried out with an intense gamma source. The detector was operated in avalanche mode and had the bakelite surface treated with linseed oil. After the irradiation the estimated dose, charge and fluence were approximately equal to the expected values after 10 years of operation in the CMS barrel region. During and after the irradiation, the RPC performance was monitored with cosmic muons and showed no relevant aging effects. Moreover, no variation of the bakelite resistance was observed.