[1] Rutherford Appleton Lab STFC, ISIS Facil, Didcot OX11 0QX, Oxon, England
[2] UCL, Dept Phys & Astron, London WC1E 6BT, England
[3] Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 71110, Crete, Greece
[4] Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France
[5] Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08854 USA