1. K. Zioutas is at the Physics Department, University of Thessaloniki, 52114 Thessaloniki, Greece, and at CERN, 1211 Geneva 23, Switzerland.
2. D. H. H. Hoffmann is at the Institut für Kernphysik, TU-Darmstadt, Schlossgartenstr. 9, 64289 Darmstadt, Germany.
3. K. Dennerl is at the Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany.
4. Th. Papaevangelou is at CERN, 1211 Geneva 23, Switzerland.