COMPASS experiment is dedicated to the study of the structure of nucleon. The previous COMPASS programme, which lasted till 2011, focused on the measurement of the gluon polarisation Delta_g/g (via two different approaches, the open charm photoproduction and the high p_T physics), of the longitudinal and the transverse quark spin structure and of the fragmentation functions. With a hadron beam, COMPASS studies the pion polarisabilities and some spectroscopy issues, as the production of new mesons and baryons, namely exotics or hybrids. COMPASS uses high intensity beams, that is, a polarised muon (or hadron) beam impinging on a longitudinally or transversely polarised target (or a liquid hidrogen target) followed by a two stage spectrometer: a first one with a large angular acceptance, followed downstream by a second one with a reduced acceptance, designed to detect particles up to more than 100 GeV/c. In its original design, as stated in the first Proposal, each spectrometer is equipped with a magnet surrounded by trackers, a set of electromagnetic and hadronic calorimeters, muon filters and a Cerenkov detector (RICH) for particle identification. The data acquisition system is based in a parallel read-out of the front-end electronics plus a distributed set of event-builders, specially designed to cope with huge data volumes.

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Contacts

Group Leader:  

Catarina Quintans