| Paper | Title | Page |
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| MOPCH051 | Operation of the First Undulator-based Femtoslicing Source | 154 |
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At the BESSY II storage ring, a source of sub-100-fs x-ray pulses with tunable polarization and excellent signal-to-background ratio has been constructed in 2004, based on laser-induced energy modulation ("femtoslicing"*) and subsequent angular separation of the short-pulse x-rays from an elliptical undulator. After commissioning and characterizing the source, short-pulse radiation is now routinely delivered for pump-probe applications. The paper summarizes the results from commissioning and operational experience as well as possible upgrade options.
*A. Zholents and M. Zoloterev, PRL 76 (1996), 912. |
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| THPLS015 | Spectral Fingerprints of Femtoslicing in the THz Regime | 3302 |
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Femtosecond (fs) THz pulses are observed as a consequence of laser-induced energy modulation of electrons in the BESSY II storage ring in order to generate fs x-ray pulses via femtoslicing*. The THz pulses are spectrally characterized by step-scan and rapid scan FTIR spectroscopy. The temporal shape of the laser-induced density modulation is reconstructed from the THz spectra. It is studied as a function of laser and storage ring parameters and monitored over several revolutions. The results are compared with numerical simulations. The THz spectra acquired over a few seconds are used to optimize the laser parameters for achieving minimum x-ray pulse lengths in femtoslicing experiments.
*A. Zholents and M. Zoloterev, PRL 76 (1996), 912. |
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| THPLS016 | Bunch Shape Diagnostics Using Femtoslicing | 3305 |
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Laser-energy modulation of relativistic electron bunches as needed for the BESSY femtosecond (fs) x-ray source is accompanied by the emission of fs THz pulses*. The total THz intensity probes the square of the longitudinal particle density within a slice of ~50 fs length (fwhm). The bunch shape can be directly monitored while sweeping the time delay between laser and bunch clock. The method is demonstrated for bunch lengths between 3 and 30 ps (rms) in different operation modes of BESSY II. The use of THz signals from successive turns and the influence of periodic bursts of coherent synchrotron radiation, which lock to the laser pulse under certain conditions, are discussed. The method is used for setting up and stabilizing the temporal overlap between a fs-laser and a relativistic electron bunch.
*K. Holldack et al., Phys. Rev. Lett. (2006), accepted Dec. 2005. |