1. High Energy Density Science Division, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
2. Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
3. Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
4. BC Cancer, Provincial Health Services Authority, Victoria, British Columbia V8R 6V5, Canada
5. Physics Department, Stanford University, Stanford, California 94305, USA
6. Applied Physics Department, Stanford University, Stanford, California 94305, USA