Measurement of the Gluon Polarization in the Nucleon at COMPASS

COMPASS (COmmon Muon and Proton Apparatus for Structure and Spectroscopy) is a fixed target experiment at CERN studying nucleon spin structure in polarized deep inelastic muon nucleon scattering and hadron spectroscopy using hadron beams. The main goal of the COMPASS spin physics program is the measurement of the helicity contribution of gluons to the nucleon spin, ΔG. Experimentally this quantity is mainly accessible via two processes in polarized deep inelastic scattering: The first one is the production of hadron pairs with large transverse momentum. The second one is open charm production which provides the cleanest and most direct measurement. The first method has a higher statistical accuracy but larger systematic uncertainties due to contributing background processes. Recent results of the COMPASS collaboration, indicating a small value for ΔG, obtained with the two methods will be presented