[1] Galway Mayo Inst Technol, Dept Life & Phys Sci, Galway, Ireland
[2] Harvard Smithsonian Ctr Astrophys, Fred Lawrence Whipple Observ, Amado, AZ 85645 USA
[3] Washington Univ, Dept Phys, St Louis, MO 63130 USA
[4] Univ Massachusetts, Dept Phys, Amherst, MA 01003 USA
[5] Univ Leeds, Sch Phys & Astron, Leeds LS2 9JT, W Yorkshire, England
[6] Smithsonian Astrophys Observ, Cambridge, MA 02138 USA
[7] Argonne Natl Lab, Argonne, IL 60439 USA
[8] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA
[9] Natl Univ Ireland Univ Coll Galway, Dept Phys, Galway, Ireland
[10] Adler Planetarium & Astron Museum, Dept Astron, Chicago, IL 60605 USA
[11] Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA
[12] Univ Utah, Dept Phys, Salt Lake City, UT 84112 USA
[13] Purdue Univ, Dept Phys, W Lafayette, IN 47907 USA
[14] Grinnell Coll, Dept Phys, Grinnell, IA 50112 USA
[15] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[16] Columbia Univ Barnard Coll, Dept Phys & Astron, New York, NY 10027 USA
[17] McGill Univ, Dept Phys, Montreal, PQ H3A 2T8, Canada
[18] Univ Delaware, Bartol Res Inst, Dept Phys & Astron, Newark, DE 19716 USA
[19] Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA
[20] Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA
[21] Univ Coll Dublin, Sch Phys, Dublin 2, Ireland
[22] Cork Inst Technol, Dept Appl Phys & Instrumentat, Cork, Ireland
[23] Univ Calif Santa Cruz, Santa Cruz Inst Particle Phys, Santa Cruz, CA 95064 USA
[24] Univ Calif Santa Cruz, Dept Phys, Santa Cruz, CA 95064 USA