1. Institute of Physics of Rennes, CNRS−University of Rennes 1, UMR 6251, F-35042 Rennes, France
2. Institut Laue-Langevin, 71 avenue des Martyrs, F-38000 Grenoble, France
3. Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science at MLZ Lichtenbergstrasse 1, 85748 Garching, Germany