1. Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
2. Swiss Plasma Center, Ecole Polytechnique Fédérale de Lausanne, 5232 Villigen PSI, Switzerland
3. Laboratory for Particle Physics, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
4. Laboratory for Scientific Developments and Novel Materials, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland