Space Sciences Lab, Universtity of California Centennial Drive at Grizzly Peak, Berkeley, CA 94720-7450, USA
Space Sciences Lab, Universtity of California Centennial Drive at Grizzly Peak, Berkeley, CA 94720-7450, USA; Physics Department, Universtiy of California, Berkeley, CA 94720-7300, USA
University of Glasgow, Kelvin Building, Glasgow, G128QQ United Kingdom
University of Maryland, Department of Physics, College Park, MD 20742, USA