1. Clemson University, 118 Kinard Laboratory Clemson, Department of Physics and Astronomy, Clemson, South Carolina, United States
2. Washington University in St. Louis, Physics Department, St. Louis, Missouri, United States
3. University of Colorado, Boulder, Colorado, United States
4. National Institute of Standards and Technology, Boulder, Colorado, United States
5. University of New Hampshire, Space Science Center, Department of Physics and Astronomy, Durham, New Hampshire, United States