1. Department of Physics, University of Central Florida 1 , Orlando, Florida 32816, USA
2. Linac Coherent Light Source, SLAC National Accelerator Laboratory 2 , 2575 Sand Hill Road, Menlo Park, California 94025, USA
3. CREOL, The College of Optics and Photonics, University of Central Florida 3 , Orlando, Florida 32816, USA
4. Department of Physics, The Ohio State University 4 , 191 W Woodruff Ave, Columbus, Ohio 43210, USA