By Kara Zielinski1, Shuo Sui2, Suzette A. Pabit, Daniel A. Rivera, Tong Wang, Qingyue Hu, Maithri M. Kashipathy, Stella Lisova, Chris B. Schaffer, Valerio Mariani, Mark S. Hunter3, Christopher Kupitz3, Frank R. Moss, Frédéric P. Poitevin, Thomas D. Grant, Lois Pollack4
1. Center for Free-Electron Laser Science 2. Unicersity of Massachusetts Amherst 3. SLAC National Accelerator Laboratory 4. Cornell University