Influence of Impact Parameter on Thermal Description of Relativistic Heavy Ion Collisions at GSI/SIS

Attention is drawn to the role played by the size of the system in the thermodynamic analysis of particle yields in relativistic heavy ion collisions at SIS energies. This manifests itself in the non-linear dependence of K+ and K- yields in $AA$ collisions at 1 -- 2 A.GeV on the number of participants. It is shown that this dependence can be quantitatively well described in terms of a thermal model with a canonical strangeness conservation. The measured particle multiplicity ratios (pi+/p, pi-/pi+, d/p, K+/pi+ and K+/K- but not eta/pi0) in central Au-Au and Ni-Ni collisions at 0.8 -- 2.0 A.GeV are also explained in the context of a thermal model with a common freeze-out temperature and chemical potential. Including the concept of collective flow a consistent picture of particle energy distributions is derived with the flow velocity being strongly impact-parameter dependent.Comment: revtex, 20 figure

Study of prompt dimuon and charm production with proton and heavy ion beams at the CERN SPS: proposal.

NA6

The LHC1 pixel detector studied in a 120 GeV/c pion test beam

Hybrid assemblies of LHC1 read-out chips and 300 mu m thick silicon pixel detectors have been tested with a 120 GeV/c pion beam at the CERN SPS. The equivalent noise charge at the input of the preamplifier is similar to 200 e(-). The particle detection efficiency is higher than 99.9%. A 30 ns wide efficiency plateau is reached for a 60 ns wide trigger pulse applied after a similar to 2 mu s delay. The 50 mu m x 50 mu m pixels yield a spatial precision of sigma = 129.4 +/- 0.2 mu m in the large pitch direction. In the other direction the precision is sigma = 12.2 +/- 0.2 mu m for single-pixel clusters and sigma = 8.2 +/- 0.2 mu m for double-pixel clusters, yielding an average of sigma = 11.4 +/- 0.2 mu m. Three different detector layouts on the same pitch were characterized. (C) 2000 Elsevier Science B.V. All rights reserved

The LHC1 pixel detector studied in a 120 GeV/c pion test beam

Hybrid assemblies of LHC1 read-out chips and 300 mu m thick silicon pixel detectors have been tested with a 120 GeV/c pion beam at the CERN SPS. The equivalent noise charge at the input of the preamplifier is similar to 200 e(-). The particle detection efficiency is higher than 99.9%. A 30 ns wide efficiency plateau is reached for a 60 ns wide trigger pulse applied after a similar to 2 mu s delay. The 50 mu m x 50 mu m pixels yield a spatial precision of sigma = 129.4 +/- 0.2 mu m in the large pitch direction. In the other direction the precision is sigma = 12.2 +/- 0.2 mu m for single-pixel clusters and sigma = 8.2 +/- 0.2 mu m for double-pixel clusters, yielding an average of sigma = 11.4 +/- 0.2 mu m. Three different detector layouts on the same pitch were characterized. (C) 2000 Elsevier Science B.V. All rights reserved

J/ψ\psi production and suppression at SPS energies

NA50We present the set of measurements carried out by the NA50 experiment to study J$\psi$ production in proton- and ion-induced reactions. We also make use of results obtained previously under similar conditions by experiments NA51, NA38 and NA3. All these measurements were performed in fixed target experiments at the CERN SPS. Due to accelerator constraints, momentum was 450, 400 and 200 GeV/c for incident proton beams (corresponding to $\sqrt{s}$=29.0, 27.4, 19.4 GeV} respectively) whereas, for ion beams, incident momentum was 200 GeV/nucleon for oxygen and sulfur and 158 GeV/nucleon for Pb beams ($\sqrt{s}$=19.4 and $\sqrt{s}$=17.2 GeV} respectively). The p–A data allow us to determine with high accuracy the absorption cross section of the (pre-)resonant $c\bar{c}$ state with nuclear matter. The J$\psi$ production cross section normally expected for ion-induced reactions can then be determined and compared to the results obtained from the data collected for oxygen- and sulfur-induced collisions. Finally, we also present the most recent results on J$\psi$ production in Pb–Pb interactions. They are based on the last data sample collected with an improved experimental set-up and are compared with the expectations inferred from similar measurements on lighter nuclei collisions

J/ψ\psi production and suppression at SPS energies

Abstract We present the set of measurements carried out by the NA50 experiment to study J/ψ production in proton- and ion-induced reactions. We also make use of results obtained previously under similar conditions by experiments NA51, NA38 and NA3. All these measurements were performed in fixed target experiments at the CERN SPS. Due to accelerator constraints, momentum was 450, 400 and 200 GeV/c for incident proton beams (corresponding to sqrt{s}=29.0, 27.4, 19.4,{rm GeV} respectively) whereas, for ion beams, incident momentum was 200 GeV/nucleon for oxygen and sulfur and 158 GeV/nucleon for Pb beams (sqrt{s}=19.4 and sqrt{s}=17.2,{rm GeV} respectively). The p–A data allow us to determine with high accuracy the absorption cross section of the (pre-)resonant {rm c}bar{rm c} state with nuclear matter. The J/ψ production cross section normally expected for ion-induced reactions can then be determined and compared to the results obtained from the data collected for oxy..

Fission cross sections of lead projectiles in Pb-nucleus interactions at 40 and 158 GeV/c per nucleon

NA50 E