1. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025
2. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720
3. Department of Physics, University of California, Davis, Davis, California 95616
4. Synchrotron-SOLEIL, Saint-Aubin, BP48, F91192 Gif sur Yvette Cedex, France
5. Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
6. Department of Physics, Temple University, Philadelphia, Pennsylvania 19122