1. Nuclear Physics Group, School of Physics and Astronomy, Schuster Laboratory, The University of Manchester, Brunswick Street, Manchester M13 9PL, United Kingdom
2. Department of Physics, University of Jyväskylä, Survontie 9, FI-40014 Jyväskylä, Finland
3. CERN, CH-1211, Geneva 23, Switzerland
4. Department of Quantum Engineering, Nagoya University, Nagoya, Aichi 464-8603, Japan