1. Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Kbh K, Denmark;
2. Ravnholtvej 23, Rårup, DK-7130 Juelsminde, Denmark;
3. Division of Nuclear Physics, Department of Physics, Lund University, Professorsgatan 1, 221 00 Lund, Sweden;
4. Rennesveien 14, N-4513 Mandal, Norway;