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0. ). The, J. Daillant, A. Nadji, P. Morin, A. Taleb et al., Rousse for their support. The authors would like also to thank members of the Accelerator and Engineering Division and of the Experimental Division of SOLEIL, J. L. Lancelot

S. C. Author, J. G. , J. P. , G. L. , B. M. et al., worked on the laserbased electron acceleration. The line was designed by