M. Sitta

Observation of a threshold effect in the anomalous J/ψ suppression

Abstract We report on a search for a phase transition from ordinary nuclear matter to a state of deconfined quarks and gluons as predicted by lattice QCD calculations. A new measurement of charmonium production in Pb-Pb interactions at 158 GeV/ c per nucleon agrees with our previous results and confirms the anomalous J/ ψ suppression we had already observed on a significantly smaller data sample. New event selection and analysis techniques show that, for peripheral collisions, the J/ ψ cross-section per nucleon-nucleon collision agrees with the precise suppression pattern inferred from a wide range of measurements extending from p-p up to S-U collisions. As the collisions become more central, the Pb-Pb cross-section exhibits a clear departure from this normal behaviour. The onset of the anomalous J/ ψ suppression reported here is the first clear observation of a threshold effect in heavy ion collisions and can be considered as a strong indication of the production of a deconfined quark-gluon phase in central Pb-Pb collisions.

Charmonium production and nuclear absorption in p-A interactions at 450 GeV

Abstract.The production of

Transverse momentum distributions of J/ψ, ψ′, Drell–Yan and continuum dimuons produced in Pb–Pb interactions at the SPS

{\rm J}/\psi

Results on leptonic probes from NA50

and

Transverse momentum distribution of J/Ψ produced in PbPb and p-A interactions at the CERN SPS

\psi^\prime

Charmonia absorption in p-A collisions at the CERN SPS results and implications for PbPb interactions

charmonium states in proton-nucleus interactions has been investigated by the NA50 experiment, at the CERN SPS. High statistics data sets were collected with collisions induced by 450 GeV protons incident on Be, Al, Cu, Ag and W targets. The

Operation and calibration of the Silicon Drift Detectors of the ALICE experiment during the 2008 cosmic ray data taking period

{\rm J}/\psi

J/ψ azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon

and

The production of phi , omega and rho mesons in p-, d-, S- and Pb-induced reactions at the CERN SPS

\psi^\prime

Results on open charm from NA50

production cross-sections have been determined for each p-A system and their dependences on the nucleus size have been studied, leading to the so-called normal nuclear absorption. Comparing the two patterns we see that the nuclear absorption is stronger for the