The ALICE muon spectrometer: trigger detector performance and readiness for the first physics measurements.

In the context of the ALICE muon trigger system, the first item of this thesis work consists in the commissioning “in situ” of the RPCs operated in highly-saturated avalanche mode and the monitoring of their performances in the first two years of LHC operations. The effects of the medium produced in ion collisions on the production process of J/psi can be quantified using as a reference the measurements of the same process in proton-proton collisions at the same N-N centre of mass energy. Since p-p data at this reference energy are not available at all or the statistics do not permit exhaustive differential kinematical distribution measurements, phenomenological approaches have been developed for predicting the inclusive J/psi production cross section in proton-proton collisions and its kinematical distributions at energies of interest for heavy-ion data studies.