Open-Charm results on gluon polarisation from COMPASS

The gluon polarisation in the nucleon has been determined by detecting open-charm production in photon-gluon fusion processes. The data were taken by the COMPASS Collaboration at CERN between 2002 and 2006, colliding a polarised muon beam on a polarised deuteron target. At leading order QCD, an average gluon polarisation of $\langle\Delta g/g\rangle_{x}= -$0.49 $\pm$ 0.27($stat$) $\pm$ 0.11($syst$) at a scale $\mu^{2}\approx$ 13 $(GeV/c)^{2}$, and at an average gluon momentum fraction $\langle x\rangle\approx$ 0.11, was estimated.