[1] Univ Siegen, D-57068 Siegen, Germany
[2] Univ Tecn Lisboa, LIP, P-1100 Lisbon, Portugal
[3] Univ Tecn Lisboa, Inst Super Tecn, P-1096 Lisbon, Portugal
[4] Univ Turin, Osservatorio Astron Torino, INAF, Turin, Italy
[5] Ist Nazl Fis Nucl, I-10125 Turin, Italy
[6] Univ Wisconsin, Madison, WI USA
[7] Fermilab Natl Accelerator Lab, Batavia, IL USA
[8] Univ Sao Paulo, Inst Fis, BR-01498 Sao Paulo, Brazil
[9] Ctr Atom Bariloche, San Carlos De Bariloche, Rio Negro, Argentina
[10] CNEA UNCuyo CONICET, Inst Balseiro, San Carlos De Bariloche, Rio Negro, Argentina
[11] NYU, New York, NY USA
[12] Ohio State Univ, Columbus, OH 43210 USA
[13] Univ Tecnol Nacl, Facultad Reg Buenos Aires, Buenos Aires, DF, Argentina
[14] Inst Tecnol Detecc Astroparticulas, CNEA, CONICET, UNSAM, Buenos Aires, DF, Argentina
[15] Univ Nacl Autonoma Mexico, Mexico City 04510, DF, Mexico
[16] Univ Santiago de Compostela, Santiago De Compostela, A Coruna, Spain
[17] Univ Hamburg, Hamburg, Germany
[18] Univ Naples Federico II, Naples, Italy
[19] Sezione Ist Nazl Fis Nucl, Naples, Italy
[20] Radboud Univ Nijmegen, IMAPP, NL-6525 ED Nijmegen, Netherlands
[21] Univ Wisconsin, Milwaukee, WI 53201 USA
[22] Rudjer Boskovic Inst, Zagreb 10000, Croatia
[23] Univ Complutense Madrid, Madrid, Spain
[24] Univ Paris 06, CNRS IN2P3, LPNHE, Paris, France
[25] Univ Paris 07, CNRS IN2P3, LPNHE, Paris, France
[26] Univ Grenoble 1, CNRS IN2P3, LPSC, Grenoble, France
[27] Nacl Energia Atom, Observat Pierre Auger & Comis, Malargue, Argentina
[28] Univ Politehn Bucuresti, Bucharest, Romania
[29] Univ Adelaide, Adelaide, SA, Australia
[30] Univ Paris 11, CNRS IN2P3, LAL, Orsay, France
[31] Karlsruhe Inst Technol, Inst Kernphys, D-76021 Karlsruhe, Germany
[32] Karlsruhe Inst Technol, Inst Expt Kernphys, D-76021 Karlsruhe, Germany
[33] Ohio State Univ, Columbus, OH 43210 USA
[34] Berg Univ Wuppertal, Wuppertal, Germany
[35] Max Planck Inst Radioastron, D-53121 Bonn, Germany
[36] Acad Sci Czech Republ, Inst Phys, Prague, Czech Republic
[37] Ist Nazl Fis Nucl, Lab Nazl Gran Sasso, Assergi, Italy
[38] Univ Fed Rio de Janeiro, Inst Fis, Rio De Janeiro, Brazil
[39] Inst Nucl Phys PAN, Krakow, Poland
[40] Colorado State Univ, Ft Collins, CO 80523 USA
[41] Horia Hulubei Natl Inst Phys & Nucl Engn, Bucharest, Romania
[42] Colorado State Univ, Pueblo, CO USA
[43] Univ Granada, Granada, Spain
[44] CAFPE, Granada, Spain
[45] Penn State Univ, University Pk, PA 16802 USA
[46] Univ Milan, Milan, Italy
[47] Sezione Ist Nazl Fis Nucl, Milan, Italy
[48] Univ Roma Tor Vergata, I-00173 Rome, Italy
[49] Sezione Ist Nazl Fis Nucl, Rome, Italy
[50] Univ Catania, Catania, Italy