John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Summary of Related Topics from the Miniworkshop on XFEL Short Bunch Measurement and Timing John Arthur LCLS

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 ICFA Future Light Sources Subpanel Miniworkshop on XFEL Short Bunch Measurement and Timing Stanford Linear Accelerator Center, July , Organizers: J. Hastings, P. Krejcik, H. Schlarb, J. Wu

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 This workshop will focus on the issues of measuring and synchronizing ultra-short bunches in linac-based FELs. Three primary themes will be addressed at the workshop: Measurement techniques for the determining the electron bunch length and arrival time. Measurement techniques, theory and simulation for diagnosing spontaneous undulator and XFEL radiation to determine its temporal profile. Issues of timing and synchronization of ultra-fast lasers to the electron bunch and RF.

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 P. Emma The workshop featured a concise, eccentric history of American baseball

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 X-ray diagnostics of FEL performance

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 W. Fawley Simulations show development of FEL beam in undulator

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 V. Sajaev Typical single-shot spectrum Average spectrum long bunch short bunch Distinctive spectral fluctuations of FEL pulses

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 D. Peter Siddons At 8 keV, Range of  E/E >10 -3 possible Resolution of possible Resolution of possible with backscattering and asymmetric reflections, but range would be reduced To resolve LCLS spectrum, need single-shot x-ray spectrometer with resolution of 10 -6

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Discussions of x-ray diagnostics and radiation properties Focused on diagnostics which will help FEL performance Intensity, propagation of pulse shape, spectrum are all important Spectral measurement needs dE/E<10 -6 to see spikes Ability to turn off undulator sections is vital Questions: Effect of reflections/aperturing by beam pipe How chirp helps or hurts How to organize data How best to correlate x-ray with optical laser How coherent (spatially) will the LCLS be

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Electron diagnostics for XFELs

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 EO Crystal Electro-Optic Sampling encodes electron pulse shape on a laser pulse

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 polarizing beamsplitter time; space time integrated intensity

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Single-Shot w/ high frequency filtering iCCD counts time (ps) color representation Timing Jitter Data (20 Successive Shots) time (ps) shot EOS data from SPPSA. Cavalieri

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Talks on EOS were given by A. Cavalieri, S. Düsterer, H. Loos, A. Winter, D. Reis, and S. Jamison

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 An interferometer can be used to autocorrelate Coherent Transition Radiation, giving a measure of electron bunch length P. Muggli

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Electron bunch measurements using a transverse RF deflector V 0  20 MV  z  50  m, E  28 GeV eeee zzzz 2.44 m cccc pppp   90° V(t)V(t)V(t)V(t) yyyyRF‘streak’ S-band P. Emma

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 Many other talks discussed aspects of timing jitter measurement and control

John Arthur LCLS Diagnostics and Commissioning September 22, 2004 General Conclusions Electron diagnostics seem to be more advanced than x-ray diagnostics Need to sharpen the requirements for diagnostics Need to coordinate/share results of experiments Simulations will play a large role What’s up with these Cub fans?