Affiliation: | (1) Department of Physics and Astronomy, Queen’s University, Belfast, BT7 1NN, UK;(2) Blackett Laboratory, Imperial College, London, SW7 2BZ, UK;(3) SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK;(4) Central Laser Facility, CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK |