Detection of heavy quark resonances with heavy ion beams in CMS

Performances of CMS in measuring J/psi and Upsilon production in heavy ion collisions are investigated. Resonance cross-sections and secondary particle multiplicities are calculated as a function of the collision impact parameter. The most unfavourable assumptions are considered for the hadron multiplicity in central collisions and their P_T distributions. Results for lead and calcium beams are presented. The Upsilon acceptance reaches an acceptable value when the analysis is restricted to the barrel region ( |eta|<1.5) and to muons with a transverse momentum P_T > 3.5 GeV/c. The dimuon mass spectra obtained for one month of data taking are presented. Statistics and Signal/Background ratios allow to conclude that CMS has good capabilities for thess studies.