Characterizing Temporal Structure of the Relativistic Electron Bunch
  Using proper beam energy chirp and the undulator detuning effect, we propose a modified optical replica synthesizer scheme to characterize the temporal structure of a relativistic electron bunch, which predicts a 100-fs temporal resolution in numerical simulation. The proof of principle experiment demonstrates a peak current of 9 A and a slice energy spread of about 0.5 keV for the uncompressed electron beam of the Shanghai Deep UV Free Electron Laser Facility. 
Haixiao Deng, Chao Feng, Bo Liu, Dong Wang, Xingtao Wang, Meng Zhang
physics.acc-ph physics.optics