[1] Univ Washington, Dept Phys, Seattle, WA 98195 USA
[2] Univ Calif Berkeley, Lawrence Berkeley Lab, Div Nucl Sci, Berkeley, CA 94720 USA
[3] Jefferson Lab, Newport News, VA 23606 USA
[4] Univ Arizona, Dept Phys, Tucson, AZ 85721 USA
[5] Brookhaven Natl Lab, RIKEN BNL Res Ctr, Upton, NY 11973 USA