[1] Paul Scherrer Inst, Villigen, Switzerland
[2] Swiss Fed Inst Technol, Inst Teilchen & Astrophys, Zurich, Switzerland
[3] Johannes Gutenberg Univ Mainz, PRISMA Cluster Excellence, Mainz, Germany
[4] Johannes Gutenberg Univ Mainz, Inst Nucl Phys, Mainz, Germany
[5] KULeuven, Inst Kern En Stralingfys, B-3001 Leuven, Belgium
[6] LKB Paris, Paris, France
[7] Univ Groningen, VSI, Groningen, Netherlands
[8] Max Planck Inst Kernphys, Heidelberg, Germany
[9] Johannes Gutenberg Univ Mainz, Inst Phys, Mainz, Germany
[10] Univ Pisa, Dept Phys, Pisa, Italy
[11] Univ Victoria, Victoria, BC, Canada
[12] Perimeter Inst, Waterloo, ON, Canada
[13] Univ Paris Sud, CSNSM, CNRS, IN2P3, Orsay, France
[14] Inst Laue Langevin, CS 20156, F-38042 Grenoble 9, France