1990-1993:   European Committee for Future Accelerators, EFCA

2000-2009:   Physics Working Group of SCAR (Scientific Committee on Antarctic Research)

2001-2008:   External Review Committee of ANTARES

2003-2012:   Peer Review Committee of ApPEC (Astroparticle Physics European Coordination)

2006-2012:   Chair of the ApPEC Peer Review Committee

2003-2006:   Chair of the R.W. Pohl Price Committee, DPG

2003-2006:   External Review Committee APC (Paris)

2007-2013:   Komitee für Astroteilchen-Physik, KAT

2011-2013:   Chair of Komitee für Astroteilchen-Physik, KAT

2008-2011:   PANAGIC (Particle And Nuclear Astrophysics and Gravitational International Committee)

since 2008:   Editorial Board of the European Journal of Physics C

2009-2014:   CERN Science Policy Committee

2011-2016:   Kuratorium Physik Journal

2011-2012:   KM3NeT Scientific Standing Committee

since 2011:   NIKHEF Scientific Committee

since 2012:   CTA Scientific and Technical Advisory Committee

since 2012:   INFN International Evaluation Committeee

2013-2017:   Stellv. Vorsitzender des Fachverbandes Teilchenphysik in der DPG

2013-2014:   Scientific Committee of the Modane Underground Laboratory

since 2013:   KM3NeT Scientific and Technical Advisory Committee

since 2013:   Auger Scientific Advisory Committee

2014-2016:   Astroparticle Physics International Committee (ApPIC)

since 2014:   Science Advisory Committee of Baikal GVD

since 2014:   Kuratorium Welt der Physik

since 2014:   Chair GVD Technical Advisory Board