P. Finetti, E. Allaria, B. Diviacco, C. Callegari, B. Mahieu, J. Viefhaus, M. Zangrando, G. De Ninno, G. Lambert, E. Ferrari, J. Buck, M. Ilchen, B. Vodungbo, N. Mahne, C. Svetina, C. Spezzani, S. Di Mitri, G. Penco, M. Trovò, W. Fawley, P. Rebernik, D. Gauthier, C. Grazioli, M. Coreno, B. Ressel, A. Kivimäki, T. Mazza, L. Glaser, F. Scholz, J. Seltmann, P. Gessler, J. Grünert, A. De Fanis, M. Meyer, A. Knie, S. Moeller, L. Raimondi, F. Capotondi, E. Pedersoli, O. Plekan, M. Danailov, A. Demidovich, I. Nikolov, A. Abrami, J. Gautier, J. Lüning, P. Zeitoun, L. Giannessi
FERMI, based at Elettra (Trieste, Italy) is the first free electron laser (FEL) facility operated for user experiments in
seeded mode. Another unique property of FERMI, among other FEL sources, is to allow control of the polarization state
of the radiation. Polarization dependence in the study of the interaction of coherent, high field, short-pulse ionizing
radiation with matter, is a new frontier with potential in a wide range of research areas. The first measurement of the
polarization-state of VUV light from a single-pass FEL was performed at FERMI FEL-1 operated in the 52 nm-26 nm
range. Three different experimental techniques were used. The experiments were carried out at the end-station of two
different beamlines to assess the impact of transport optics and provide polarization data for the end user. In this paper
we summarize the results obtained from different setups. The results are consistent with each other and allow a general
discussion about the viability of permanent diagnostics aimed at monitoring the polarization of FEL pulses.
Free-electron lasers offer a variety of unique properties for spectroscopy and imaging. The combination of high peak brilliance and a high repetition rate opens a window to experiments that have not been feasible so far but also introduces challenges in sample preparation and refreshment. First experiments at the Linac Coherent Light Source (LCLS) in Stanford showed the potential of free electron lasers for serial X-ray crystallography as well as for imaging non-reproducible objects. Owing to the superconducting accelerator technology, the European X-ray Free-Electron Laser Facility (European XFEL) will allow an average repetition rate of up to 27 kHz with bunch separation in the order of 200 ns. This extremely high repetition rate gives great chances for the scientific impact of the European XFEL, but it also comes with challenges for providing fresh samples for each bunch. This contribution will give an overview of the sample environment techniques that are in consideration for the European XFEL Facility. These techniques include gas phase, liquid, and aerosol sources for life science and physics experiments.
KEYWORDS: Diagnostics, Spectroscopy, Polarization, X-rays, Field programmable gate arrays, Gases, Principal component analysis, Free electron lasers, Data storage, Photoemission spectroscopy
The European X-ray Free Electron Laser (XFEL.EU) under construction will provide highly brilliant soft to hard X-ray (<280 eV - <20 keV) radiation with an intra-bunch train repetition rate of 4.5 MHz by employing the self-amplified spontaneous emission process. The resulting statistical fluctuations of important beam characteristics makes pulse-to-pulse diagnostics data of the photon beam a mandatory reference during user experiments. We present our concepts of analysing the photoemission from rare gases with a time-of-flight spectrometer for non-invasive, pulse-to-pulse measurements of the photon spectrum and polarization with a special emphasis on real-time processing with a low latency of ≤ 10−5 s.
X-ray Free-Electron-Laser (XFEL) facilities like the Linac Coherent Light Source (LCLS) in the USA, SACLA in Japan,
and the European XFEL under construction in Germany are 4th generation light sources which allow research of at the
same time extremely small structures (Ångström resolution) and extremely fast phenomena (femtosecond resolution).
Unlike the pulses from a conventional optical laser, the radiation in these sources is created by the Self-Amplified
Spontaneous Emission (SASE) process when electron bunches pass through very long segmented undulators. The shot
noise at the origin of this process leads to significant pulse-to-pulse variations of pulse intensity, spectrum, wavefront,
temporal properties etc. so that for user experiments an online monitoring of these properties is mandatory. Additionally,
the adjustment of the long segmented undulators requires dedicated diagnostics such as an undulator commissioning
spectrometer and spontaneous radiation analysis.
The extreme brilliance and resulting single-shot damage potential are difficult to handle for any XFEL diagnostics. Apart
from the large energy range of operation of the facility from 280eV to 25keV in FEL fundamental, the particular
challenge for the European XFEL diagnostics is the high intra bunch train photon pulse repetition rate of 4.5MHz,
potentially causing additional damage by high heat loads and making shot-to-shot diagnostics very demanding. This
presentation reports on the facility concepts, recent progress in instrumentation development, and the choices to
compromise diagnostics performance between resolution/accuracy on one hand and shot-to-shot capabilities and energy
range on the other.
At the European X-ray Free Electron Laser facility one‐ or two‐ Si(111) channel (cut) crystal X‐ray monochromator (Kmonochromator) are planned for photon beam based alignment: gap tuning of the undulator segments and phase tuning of the phase shifters during commissioning and maintenance of the undulators. A prototype device has been built using a single channel-cut crystal and was characterized at PETRAIII synchrotron (at P01, which is the only beamline with two undulator segments) by applying different undulator adjustment methods, intended for the European XFEL, that use imaging and intensity detection. This paper presents the setup and the first results from the experimental qualification of the K-monochromator prototype.
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