1. Radiochemistry Unit, Department of Chemistry, University of Helsinki, A.I. Virtasen aukio 1, 00014 Helsinki, Finland
2. Department of Geosciences and Geography, University of Helsinki, Gustaf Hällströmin katu 2, 00014 Helsinki, Finland
3. Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland
4. Helsinki Institute of Physics, PO Box 64, FI-00014 Helsinki, Finland