The authors apologise for omitting a group of authors from the author list in the published article. The missing names are listed here:
Raffaella Testoni, Antonio Zurzolo, Roberto Bonifetto, Antonio Froio
Affiliation:
Energy Department, Politecnico di Torino, Corsa Duca degli Abruzzi, 24 Torino (Italy)
INFN Torino, via Pietro Giuria 1, Torino (Italy)