The status of the COMPASS experiment

The COMPASS experiment at the SPS at CERN is investigating the spin structure of the nucleon via deep inelastic scattering of polarised muons on polarised nucleons. Currently, the main emphasis lies on the measurement of the gluon polarisation and a study of transverse quark distributions. For this purpose we use a newly built 2-stage large acceptance spectrometer supplemented by particle identification via RICH, calorimetry and muon identification. This setup allows to detect events in the quasi-real photoproduction regime which is required for the measurement of the gluon polarisation. First data were taken in 2002 with longitudinally and transversely polarised LiD targets. Currently the data are being analysed, the reconstruction is mostly done while improvements of the algorithms are still going on. The Analysis is concentrated on Lambda polarisation, vector meson production, gluon polarisation, transverse asymmetries and semi- inclusive DIS. (5 refs).