1. Institut Max von Laue-Paul Langevin, 38042 Grenoble, France
2. The European Organization for Nuclear Research, 1211 Geneva, Switzerland
3. Physics Department, University of Virginia, Charlottesville, VA 22904, USA
4. Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
5. Laboratoire de Physique Subatomique et de Cosmologie/IN2P3-UJF-INPG, 38000 Grenoble, France