Recent measurement of $\Delta G/G$ at COMPASS

The determination of the gluon polarization in the nucleon is one of the main goals of the COMPASS experiment at CERN. To do this, we collide a polarized 160 GeV muon beam on a nucleon in a polarized $^{6}$LiD target, and compute the resulting helicity asymmetry. $\frac{\Delta G}{G}$ is related to this asymmetry via the Photon-Gluon Fusion process, in which the virtual photon emitted by the muon interacts with a gluon from the nucleon to give a quark-antiquark pair. These processes are tagged either by the detection of a charmed D meson, or by requiring 2 hadrons with high transverse momentum in the final state. From the measured asymmetry of the latter channel, based on a preliminary analysis of 2002 and 2003 data, we were able to obtain the most precise direct estimation up to now of$\frac{\Delta G}{G}(x)$ at a nucleon momentum fraction x carried by the gluon around 0.1.