[1] Ist Nazl Fis Nucl, Sez Napoli, I-80125 Naples, Italy
[2] Univ Naples Federico II, I-80126 Naples, Italy
[3] Univ Salerno, I-84084 Fisciano, Salerno, Italy
[4] Ist Nazl Fis Nucl, Sez Perugia, I-06100 Perugia, Italy
[5] Univ Perugia, I-06123 Perugia, Italy
[6] Ist Nazl Fis Nucl, Sez Pisa, Pisa, Italy
[7] Univ Pisa, I-56127 Pisa, Italy
[8] Observ Cote Azur, Dept Artemis, F-06304 Nice, France
[9] Ist Nazl Fis Nucl, Lab Nazl Frascati, I-00044 Frascati, Roma, Italy
[10] EGO, I-56021 Cascina, PI, Italy
[11] Univ Paris 11, CNRS, IN2P3, LAL, F-91898 Orsay, France
[12] Lab Annecy Le Vieux Phys Particules, F-74941 Annecy Le Vieux, France
[13] ESPCI, F-75005 Paris, France
[14] Ist Nazl Fis Nucl, Sez Roma, Rome, Italy
[15] Univ Roma La Sapienza, I-00185 Rome, Italy
[16] Ist Nazl Fis Nucl, Sez Firenze Urbino, I-50019 Urbino, Italy
[17] Univ Florence, I-50125 Florence, Urbino, Italy
[18] Univ Urbino, I-60129 Urbino, Italy
[19] LMA, F-69622 Villeurbanne, Lyon, France