1. Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14623, USA
2. Department of Physics and Astronomy, Rice University, 6100 S. Main, Houston, TX 77521, USA
3. Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA
4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA