1. Center for Advanced Radiation Therapies, Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415‐3890
2. Medical Department, Brookhaven National Laboratory, Upton, New York 11973‐5000
3. HFR Unit, Joint Research Centre, Commission of the European Communities, Petten, The Netherlands NL‐1755 ZG
4. VTT Chemical Technology, Technical Research Centre of Finland, Reactor Laboratory, Espoo, Finland FIN‐02044
5. Department of Physics, University of Helsinki, Helsinki, Finland FIN‐00014
6. E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720