| Paper | Title | Page |
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TUOB03 |
Complete Ultrafast X-ray Pulse Characterization at FELs | |
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| The ability to fully characterize X-ray pulses from free electron-lasers will underpin their exploitation in experiments ranging from single-molecule imaging to extreme timescale X-ray science. This issue is especially acute when confronted with the characteristics of current generation FELs operating on the principle of SASE, as most parameters fluctuate strongly from pulse to pulse. Here, we have extended the techniques of attosecond metrology with the use of single-cycle terahertz (THz) pulses, allowing for simultaneous, in-line, single-shot measurement of both the arrival time and temporal profile of FEL pulses on an absolute scale. The technique is non-invasive and could be incorporated in pump-probe experiments, eventually leading to characterization before and after interaction with most sample environments. Optical-laser-driven THz streaking measurements, revealing X-ray pulse structure shorter than 50 fs FWHM in the soft X-ray regime at FLASH and in the ~ keV range at LCLS will be discussed. With clear potential for improvement in resolution to the sub-10 fs regime, this method will ultimately allow for characterization of the shortest predicted few-femtosecond FEL pulses. | ||
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Slides TUOB03 [15.857 MB] | |
| WEPD54 | Characterization of Single-cycle THz Pulses at the CTR Source at FLASH | 500 |
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| At the coherent transition radiation source at the free-electron laser in Hamburg (FLASH) at DESY, single-cycle THz pulses with electric field strengths exceeding one MV/cm are generated. We present the temporal and spatial characterization of this source with the technique of electro-optic sampling using a laser system synchronized with the accelerator to better than 100 fs. This method offers a quantitative detection of the electric field of the THz pulses in the time domain. Compared to other electron-accelerator driven sources like undulator radiation, the transition radiation source provides pulses with a high bandwidth and durations shorter than one picosecond. This enables time-resolving and non-destructive experiments with radiation in the THz regime including THz pump / THz probe experiments. Broadband and intense THz pulses are expected to be valuable tools for the study of dynamics of excitation of complex materials in transient electric and magnetic fields. | ||