1. Geological Survey of Norway Leiv Erikssonssvei 39 Trondheim 7040 Norway
2. Department of Natural Sciences and Environmental Health University of South‐Eastern Norway Gullbringvegen 36 Bø 3800 Norway
3. Institute of Geological Sciences University of Bern Baltzerstrasse 1 Bern 3012 Switzerland
4. Jadar Geotjenester AS Kvernaland 4355 Norway
5. Laboratory of Ion Beam Physics ETH Zürich Zürich 8093 Switzerland