1. Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin, Germany
2. Department of Physics, King’s College London, Strand, London WC2R 2LS, United Kingdom
3. Photek Ltd., 26 Castleham Rd., Saint Leonards-on-Sea TN38 9NS, United Kingdom
4. Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany