[1] Politecn Torino, Dipartimento Elettron & Telecomunicazioni, I-10129 Turin, Italy
[2] INFN Sez Torino, I-10125 Turin, Italy
[3] INFN Sez Pisa, I-56127 Pisa, Italy
[4] INFN Sez Milano, I-20133 Milan, Italy
[5] Univ Pavia, Dipartimento Fis, I-27100 Pavia, Italy
[6] INFN Sez Pavia, I-27100 Pavia, Italy
[7] Univ Roma Tor Vergata, Dipartimento Ingn Ind, I-00133 Rome, Italy
[8] INFN Sez Roma Tor Vergata, I-00133 Rome, Italy
[9] Univ Pisa, Dipartimento Ingn Informaz, I-56122 Pisa, Italy
[10] INFN Lab Nazl Legnaro, I-35020 Legnaro, Italy
[11] Scuola Normale Super Pisa, NEST, I-56127 Pisa, Italy
[12] Ist Nanosci CNR, I-56127 Pisa, Italy
[13] Univ Camerino, Scuola Sci & Tecnol, Div Fis, I-62032 Camerino, Italy
[14] INFN Sez Perugia, I-06123 Perugia, Italy
[15] Univ Torino, Dipartimento Fis, I-10125 Turin, Italy
[16] Univ Pisa, Dipartimento Fis, I-56127 Pisa, Italy
[17] Univ Milan, Dipartimento Fis, I-20133 Milan, Italy
[18] Paul Scherrer Inst, CH-5232 Villigen, Switzerland
[19] Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, England
[20] Univ Pavia, Dipartimento Ingn Ind & Informaz, I-27100 Pavia, Italy
[21] Univ Napoli Federico II, Dipartimento Fis, I-80126 Naples, Italy
[22] Univ Modena & Reggio Emilia, Dipartimento Sci Fis Informat & Matemat, I-41125 Modena, Italy
[23] Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy
[24] Univ Roma Tor Vergata, Dipartimento Ingn Elettron, I-00133 Rome, Italy
[25] Swinburne Univ Technol, Space Technol & Ind Inst, Hawthorn, Vic 3122, Australia
[26] Univ Milan, Dipartimento Informat, I-20133 Milan, Italy