Measurement and calculation of the `Electron efficiency' on the `CLIO' Free-Electron Laser R. Prazeres, F. Glotin and J. M. Ortega Eur. Phys. J. Appl. Phys., 29 3 (2005) 223-230 Published online: 21 December 2004 DOI: 10.1051/epjap:2004218