Measurements of the $\Delta G/G$ at COMPASS

The main goal of the COMPASS collaboration at CERN is a quantitative determination of $\Delta G/G$. Three different approaches based on the Photon Gluon Fusion process are utilised. They rely on the PGF tagging via open charm mesons or via high–$p_{T}$ hadron pairs detection. The latter is measured in the DIS (Q$^{2} >$ 1 GeV$^{2}$) and in the quasi–real photoproduction (Q$^{2} <$ 1 GeV$^{2}$) kinematical regimes. The measurement is done with a two–stage spectrometer capable of particle registration and identification in a wide momentum range. The experiment uses a solid state, polarised $^{6}$LiD target and a 160 GeV polarised muon beam.