1. Physics Department, Duke University, Durham, North Carolina, USA 27708, USA
2. Triangle Universities Nuclear Laboratory, Durham, North Carolina, USA 27708, USA
3. Physics Department, North Carolina State University, Raleigh, North Carolina, USA 27695, USA
4. Triangle Universities Nuclear Laboratory, Durham, North Carolina, USA 27708, USA
5. Duke University Free-Electron Laser Laboratory, Durham, North Carolina, USA 27708, USA
6. Physics Department, Penn State Altoona, Altoona, Pennsylvania, USA 16601, USA
7. Institute of Physics, Jagiellonian University, PL-30059 Cracow, Poland