Wohlenberg, T.; Carlsen, F.; Henriksen, L.; Johnson, E.; Ytterhus, J. A.; Wohlenberg, T.; Physical Laboratory II, H. C. Ørsted Institute, University of Copenhagen; Carlsen, F.; Physical Laboratory II, H. C. Ørsted Institute, University of Copenhagen; Henriksen, L.; Physical Laboratory II, H. C. Ørsted Institute, University of Copenhagen; Johnson, E.; Physical Laboratory II, H. C. Ørsted Institute, University of Copenhagen; Ytterhus, J. A.; Physical Laboratory II, H. C. Ørsted Institute, University of Copenhagen; Danish AEC Research Establishment