[1] Univ Salerno, Dipartimento Fis ER Caianiello, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy
[2] Univ Salerno, Ist Nazl Fis Nucl, Grp Collegato Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy
[3] Univ Salerno, CNISM, Unita Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy
[4] Univ Campania L Vanvitelli, Dipartimento Matemat & Fis, Viale Lincoln 5, I-81100 Caserta, Italy
[5] CNR, Ist Sistemi Complessi, Via Madonna Piano 10, I-50019 Sesto Fiorentino, Italy
[6] Ist Nazl Fis Nucl, Sez Firenze, Via G Sansone 1, I-50019 Sesto Fiorentino, Italy