An approach for few femtosecond timing of fourth generation X-ray lightsources and single shot electron bunch diagnostics
by Dr. Michael Gensch (Helmholtz-Zentrum Dresden-Rossendorf)
Friday, March 25, 2011 from to (Europe/Berlin)
Fourth-generation X-ray light sources are being developed to deliver laser-like X-ray pulses at intensities and/or repetition rates that are beyond the reach of table-top devices. An important class of experiments at these new facilities comprises pump–probe experiments, which are designed to investigate chemical reactions and processes occurring on the molecular or even atomic level, and on the timescale of a few femtoseconds. Good progress has been made towards the generation of ultrashort X-ray pulses (for example, at FLASH or LCLS), but experiments suffer from the intrinsic timing jitter between the X-ray pulses and external laser sources. Here I present a new approach that provides few-femtosecond temporal resolution for pump probe experiments at FLASH. The method uses residual coherent terahertz radiation generated at the end of the X-ray undulator by the same electron bunch that emits the X-ray pulse. It can therefore be applied at any advanced light source working with ultrashort electron bunches and undulators. The employed instrumentation also has a high potential to allow analysis of the electron bunch form on a single shot basis. An outlook on how the method will be employed at the currently upgraded cw electron linac ELBE at the HZDR to aid laser-electron interaction experiments with dedicated TW and PW lasers is also given.