[1] Univ Piemonte Orientale, DISTA, Alessandria, Italy
[2] Ist Nazl Fis Nucl, Alessandria, Italy
[3] CINVESTAV, Mexico City 14000, DF, Mexico
[4] Univ Turin, Dipartimento Fis Sperimentale, Turin, Italy
[5] Ist Nazl Fis Nucl, I-10125 Turin, Italy
[6] Univ Ferrara, Dipartimento Fis, I-44100 Ferrara, Italy
[7] Ist Nazl Fis Nucl, Ferrara, Italy
[8] Univ Min & Met Krakow, Fac Phys & Nucl Tech, Krakow, Poland
[9] CEADEN, Havana, Cuba
[10] Univ Bologna, Dipartimento Fis, Bologna, Italy
[11] Ist Nazl Fis Nucl, I-40126 Bologna, Italy