Speaker
Frédéric Fleuret
(LLR Ecole Polytechnique, IN2P3/CNRS)
Description
Twenty five years ago, CERN pioneered the study of quarkonium production in heavy ion collisions at the SPS with the aim of characterizing the QGP phase transition and testing lattice QCD predictions. In 1997, the NA50 experiment observed an anomalous suppression of J/psi production in Pb+Pb collisions. Since then, these quarkonium studies have been extended to regimes of significantly higher energies as reached at BNL-RHIC and CERN-LHC. In addition with the results obtained at RHIC on J/psi and more recently at LHC on quarkonium states, hints of the theoretically expected sequential suppression start to emerge.
Nevertheless, the experimental validations of such a scenario as well as the characterization of the phase transition require full control of the feed-down sequence. In particular, a precise measurement of quarkonium 1P states which significantly contribute to the yields of quarkonium 1S states is mandatory. For charmonium, the measurement of chi_c production together with J/psi and psi’ is needed to prove the sequential suppression scenario.
For this purpose, we propose a new experiment at the CERN SPS, which makes use of modern ultra-granular technologies to perform the measurement of chi_c -> J/psi+photon in Pb+Pb high multiplicity collisions.
In this talk, after a quick reminder of the physics case, we describe the proposed apparatus and present its expected performances.
Author
Frédéric Fleuret
(LLR Ecole Polytechnique, IN2P3/CNRS)
