[1] Univ Salerno, Phys Dept, I-84084 Fisciano, Italy
[2] Ist Nazl Fis Nucl, Grp Collegato Salerno, I-84084 Fisciano, Italy
[3] CNR SPIN Salerno Sect, I-84084 Fisciano, Italy
[4] Univ Milano Bicocca, Phys Dept, I-20126 Milan, Italy
[5] Ist Nazl Fis Nucl, Sez Milano Bicocca, I-20126 Milan, Italy
[6] Univ Salento, Math & Phys Dept, I-73100 Lecce, Italy
[7] Ist Nazl Fis Nucl, Sez Lecce, I-73100 Lecce, Italy
[8] CNR INO, I-38123 Povo, Italy
[9] Univ Trento, Phys Dept, I-38123 Povo, Italy
[10] Fdn Bruno Kessler, I-38123 Povo, Italy
[11] Ist Nazl Fis Nucl, TIFPA, I-38123 Povo, Italy
[12] Ist Nazl Fis Nucl, Lab Nazl Frascati, I-00044 Frascati, Italy
[13] INRiM Ist Nazl Ric Metrol, I-10135 Turin, Italy
[14] CNR IFN, I-38123 Povo, Italy
[15] Politecn Torino, I-10129 Turin, Italy
[16] Univ Sannio, Sci & Technol Dept, I-82100 Benevento, Italy
[17] Univ Sannio, Engn Dept, I-82100 Benevento, Italy
[18] Ist Nazl Fis Nucl, Sez Torino, I-10125 Turin, Italy