%\cite{Ferrari:FEL2015-TUB04} \bibitem{Ferrari:FEL2015-TUB04} E.~Ferrari, E.~Allaria, M.B.~Danailov, G.~De Ninno, S.~Di Mitri, D.~Gauthier, \emph{et al.}, % E. Ferrari \emph{et al.}, \textquotedblleft{Influence of a Non-Uniform Longitudinal Heating on High Brightness Electron Beams for FEL}\textquotedblright, % presented at FEL2015, Daejeon, Republic of Korea, August 2015, paper TUB04, unpublished. presented at the 37th International Free Electron Laser Conference (FEL2015), Daejeon, Republic of Korea, August 2015, paper TUB04, unpublished.