[1] Univ Roma Tor Vergata, I-00173 Rome, Italy
[2] Sezione Ist Nazl Fis Nucl, Rome, Italy
[3] UNCuyo, CONICET, CNEA, Ctr Atom Bariloche, San Carlos De Bariloche, Rio Negro, Argentina
[4] UNCuyo, CONICET, CNEA, Inst Balseiro, San Carlos De Bariloche, Rio Negro, Argentina
[5] UTN, CONICET, FRBA, Comis Nacl Energia Atom,Ctr Atom Constituyentes, Buenos Aires, DF, Argentina
[6] Univ Buenos Aires, Dept Fis, FCEyN, RA-1053 Buenos Aires, DF, Argentina
[7] Univ Nacl La Plata, IFLP, La Plata, Buenos Aires, Argentina
[8] Consejo Nacl Invest Cient & Tecn, La Plata, Buenos Aires, Argentina
[9] Consejo Nacl Invest Cient & Tecn, Inst Astron & Fis Espacio, RA-1033 Buenos Aires, DF, Argentina
[10] Natl Technol Univ, CONICET, CNEA, Fac Mendoza, Mendoza, Argentina
[11] Pierre Auger So Observ, Malargue, Argentina
[12] Comis Nacl Energia Atom, Malargue, Argentina
[13] Univ Adelaide, Adelaide, SA, Australia
[14] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil
[15] Pontificia Univ Catolica Rio de Janeiro, Rio De Janeiro, Brazil
[16] Univ Sao Paulo, Inst Fis, Sao Carlos, SP, Brazil
[17] Univ Sao Paulo, Inst Fis, BR-01498 Sao Paulo, Brazil
[18] Univ Estadual Campinas, IFGW, Campinas, SP, Brazil
[19] Univ Estadual Sudoeste Bahia, Vitoria Da Conquista, BA, Brazil
[20] Univ Fed Bahia, Salvador, BA, Brazil
[21] Univ Fed ABC, Santo Andre, SP, Brazil
[22] Univ Fed Rio de Janeiro, Inst Fis, Rio De Janeiro, Brazil
[23] Rudjer Boskovic Inst, Zagreb 10000, Croatia
[24] Charles Univ Prague, Fac Math & Phys, Inst Particle & Nucl Phys, Prague, Czech Republic
[25] Acad Sci Czech Republ, Inst Phys, Prague, Czech Republic
[26] Palacky Univ, CR-77147 Olomouc, Czech Republic
[27] Univ Paris 11, CNRS, IPNO, IN2P3, F-91405 Orsay, France
[28] Univ Paris 07, CNRS, Lab AstroParticule & Cosmol, IN2P3, Paris, France
[29] Univ Paris 11, CNRS, LAL, IN2P3, F-91405 Orsay, France
[30] Univ Paris 06, CNRS, IN2P3, LPNHE, Paris, France
[31] Univ Paris 07, CNRS, IN2P3, LPNHE, Paris, France
[32] Univ Grenoble 1, CNRS, IN2P3, LPSC,INPG, Grenoble, France
[33] CNRS, IN2P3, SUBATECH, Nantes, France
[34] Berg Univ Wuppertal, Wuppertal, Germany
[35] Karlsruhe Inst Technol, Inst Kernphys, Karlsruhe, Germany
[36] Karlsruhe Inst Technol, Inst Prozessdatenverarbeitung & Elekt, Karlsruhe, Germany
[37] Karlsruhe Inst Technol, Inst Expt Kernphys, Karlsruhe, Germany
[38] Max Planck Inst Radioastron, D-5300 Bonn, Germany
[39] Rhein Westfal TH Aachen, Phys Inst A 3, Aachen, Germany
[40] Univ Hamburg, Hamburg, Germany
[41] Univ Siegen, Siegen, Germany
[42] Dept Fis Univ, Genoa, Italy
[43] Ist Nazl Fis Nucl, I-16146 Genoa, Italy
[44] Univ Aquila, I-67100 Laquila, Italy
[45] Sezione Ist Nazl Fis Nucl, Milan, Italy
[46] Univ Milan, Milan, Italy
[47] Univ Salento, Dipartimento Fis, Lecce, Italy
[48] Sezione Ist Nazl Fis Nucl, Lecce, Italy
[49] Univ Naples Federico II, Naples, Italy
[50] Sezione Ist Nazl Fis Nucl, Naples, Italy