[1] Scuola Normale Super Pisa, I-56127 Pisa, Italy
[2] Ist Nazl Fis Nucl, Sez Pisa, I-56127 Pisa, Italy
[3] Univ Pisa, Dipartimento Fis, I-56127 Pisa, Italy
[4] IRST, Fdn Bruno Kessler, Div Microsistemi, I-38050 Trento, Italy
[5] CNR, IPCF, Intense Laser Irradiat Lab, I-56127 Pisa, Italy
[6] Ist Nazl Fis Nucl, Sez Perugia, I-06123 Perugia, Italy
[7] Ist Nazl Fis Nucl, Sez Padova, Grp Collegato Trento, I-38050 Trento, Italy
[8] DEE Politecn Bari, I-70125 Bari, Italy
[9] Ist Nazl Fis Nucl, Sez Bari, I-70125 Bari, Italy