[1] Univ Alabama Huntsville, Dept Phys, ZP12, Huntsville, AL 35899 USA
[2] Goethe Univ, Inst Theoret Phys, D-60438 Frankfurt, Germany
[3] Inst Nucl Phys PAN, Ul Radzikowskiego 152, PL-31342 Krakow, Poland
[4] Univ Potsdam, Inst Phys & Astron, D-14476 Potsdam, Germany
[5] DESY, Platanenallee 6, D-15738 Zeuthen, Germany
[6] CSIC, Inst Astrofis Andalucia, Apartado 3004, E-18080 Granada, Spain
[7] Inst Space Sci, Atomistilor 409, RO-077125 Bucharest, Romania
[8] Univ Coll Cork, Dept Phys, Cork T12 YN60, Ireland
[9] Univ Copenhagen, Niels Bohr Inst, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
[10] Univ Ghent, Dept Phys & Astron, Proeftuinstr 86, B-9000 Ghent, Belgium
[11] Observ Paris, LUTH, 5 Pl Jules Jansen, F-92195 Meudon, France
[12] Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA
[13] Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA