105 research outputs found
Design and operation of a fast high-granularity silicon detector system in a high-radiation environment
Abstract We have designed, realized and operated a fast silicon detector system (50 MHz sampling frequency) to measure the angular distribution and the multiplicity of charged secondaries produced in high-energy PbâPb interactions, within the NA50 experiment. We present here the detector design, discuss some of the problems faced during the commissioning and report on the first results on the operation of the full system. In particular, the questions related to the operation of an integrated high-speed binary readout in a high-radiation environment (1014 particles/cm2 and about 10 Mrads) and to the radiation effects on the system during the run will be addressed
Anomalous suppression in Pb-Pb interactions at 158 GeV per nucleon
The Drell-Yan and J/psi cross-sections measured in Pb-Pb collisions are compared with the values extrapolated from the results obtained in proton and light ion induced reactions. While the Drell-Yan production exhibits the normal expected behaviour, the yield of J/psi in Pb-Pb interactions is abnormally low, as it lies 9 standard deviations below the expected value. Moreover, the departure from the expected behaviour increases significantly from peripheral to central collisions. (C) 1997 Elsevier Science B.V
Charmonium production in Pb-Pb collisions
NA50The elaboration of specific media-planning is necessary to communicate with an opinion leader. Opinion leaders in 27 product categories are selected from a 10,000 sample of French representative consumers. Magazine is the favorite media of opinion leaders; the more important is the number of product categories in which a consumer is leaders, the greater the media consumption. Leaders do not systematically prefer the Internet, their preference appears to be category specific. However, a second study conducted among 600 brand website visitors shows that brand sites represent a major information source for the leaders
Transverse momentum distributions of , Drell-Yan and continuum dimuons produced in Pb-Pb interactions at the SPS
NA50Muon pairs produced in Pb-Pb interactions at 158~GeV/ per nucleon are used to study the transverse momentum distributions of the \jpsi, \psip\ and dimuons in the mass continuum. In particular, the dependence of these distributions on the centrality of the Pb-Pb collision is investigated in detail
Results on Charmonium States in Pb-Pb Interactions
We present cross-sections for J/, and Drell-Yan production in lead-lead interactions at 158 GeV/nucleon. The Pb-Pb data, when compared with previous results obtained with lighter target or projectiles, show a similar behaviour for Drell-Yan, but exhibit an anomalous J/ suppression, which increases with centrality
Low mass dimuon production in proton and ion induced interactions at SPS
The low mass dimuon spectra collected in p-U collisions by the NA38 experiment significantly exceeds the total cross section expected from previous analysis, done by other experiments. The `excess' events have a harder \pt\ distribution than the muon pairs from and Dalitz decays, expected to dominate the mass window 0.4--0.65~GeV/. We conjecture that the excess events might be due to \qqbar\ annihilations, negligible at low \pt\ but made visible by the \mt\ cut applied in the NA38 data. Taking this assumption to parametrise the p-U spectra, we proceed with the analysis of the S-Cu, S-U and Pb-Pb data, collected by the NA38 and NA50 experiments, where we find that the measured mass spectra does not seem to exceed the expected low mass `cocktail' by more than 20\,\%
Low mass dimuon production in proton and ion induced interactions at SPS
The low mass dimuon spectra collected in -U collisions by the NA38 experiment significantly exceeds the total cross section expected from previous analysis, done by other experiments. The 'excess' events have a harder distribution than the muon pairs from and Dalitz decays, expected to dominate the mass window 0.4â0.65~GeV/. We conjecture that the excess events might be due to annihilations, negligible at low but made visible by the cut applied in the NA38 data. Taking this assumption to parametrise the -U spectra, we proceed with the analysis of the S-Cu, S-U and Pb-Pb data, collected by the NA38 and NA50 experiments, where we find that the measured mass spectra does not seem to exceed the expected low mass `cocktail' by more than 20%
- âŠ