1 The James Franck Institute and Department of Physics, The University of Chicago, Chicago, IL 60637; Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439;
2 The James Franck Institute and Department of Physics, The University of Chicago, Chicago, IL 60637; Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831;
3 School of Physics, The University of Bristol, Bristol BS8 1TL, United Kingdom; and.
4 The James Franck Institute and Department of Physics, The University of Chicago, Chicago, IL 60637;
5 Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831;
6 Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439;
7 Department of Physics and Astronomy and Brockhouse Institute for Material Research, McMaster University, Hamilton, ON, Canada L8S 4M1.
8 The James Franck Institute and Department of Physics, The University of Chicago, Chicago, IL 60637; tfr@caltech.edu.