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Online Tender X-ray Spectrometer at SwissFEL

English title Online Tender X-ray Spectrometer at SwissFEL
Applicant Juranic Pavle
Number 177003
Funding scheme R'EQUIP
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Other disciplines of Physics
Start/End 01.09.2018 - 28.02.2021
Approved amount 240'000.00
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Keywords (4)

Online; Single-shot; Diagnostics; Spectroscopy

Lay Summary (German)

X-ray free electron lasers (XFEL) sind sehr starke Werkzeuge für die Forschung der natürlichen Phänomenen, aber benötigen die konstante Überwachung ihren Eigenschaften, die puls-zu-puls sich ändern. Ein grosser Aufwand ist die on-line Messung des X-ray Spektrums für die benutzte Photon Pulsen in der so-genannte tender X-ray Region. Diese Region ist sehr wichtig für biologische und chemische Forschung, und es gab kein Werkzeug, damit man das Spektrum on-line messen könnte. Das Tender X-ray Spektrometer (TXS) ist gebaut, diese Welt-weite Unzulänglichkeit zu korrigieren.
Lay summary

Forscher wollten seit Jahren den vollen Strahl der X-rays in den tender Energiebereich bei FELs ausnutzen, aber brauchen dafür neue Art online Diagnostikgerate, damit ihre Experimente auf dem höchsten Niveau von Precision gemacht sein können.   Eine von den Eigenschaften, die gemessen sein muss, um diesen Niveau zu erreichen, ist die nicht-zusteuernden pulse-zu-pulse Spektralmessung, die jetzt mit dem TXS gemacht sein können.  Das TXS benutzt Methoden, Technologien und Detektoren, die von dem Schweizer Paul Scherrer Institut (PSI) entwickelt sind, um dünne Folien, gebogene Kristalle, und hoch-genauigkeit X-ray Roentgenstrahlungdetektoren zu kombinieren, und damit die Photoenergiespektrum jedes Pulses in der Tender  X –ray Energie Bereich zu messen.   Das TXS wird in der Alvra Beamline des SwissFELs bei PSI eingebaut, aber wird klein genügend sein, auch problemlos zu anderen FELs transportiert und installiert zu sein.

Direct link to Lay Summary Last update: 21.06.2018

Responsible applicant and co-applicants


A compact and versatile tender X-ray single-shot spectrometer for online XFEL diagnostics
Rehanek Jens, Milne Christopher J., Szlachetko Jakub, Czapla-Masztafiak Joanna, Schneider Jörg, Huthwelker Thomas, Borca Camelia N., Wetter Reto, Patthey Luc, Juranić Pavle (2018), A compact and versatile tender X-ray single-shot spectrometer for online XFEL diagnostics, in Journal of Synchrotron Radiation, 25(1), 16-19.


Experiments with a free electron laser (FEL) typically require dedicated end stations that are at the disposal of the users who come to measure at the FEL facility. These stations are physically and organizationally separated from the standard FEL beamline components, like mirrors, slits, vacuum systems, and screens, focused on providing users with the tools they need to do experiments instead of just providing a light source, which is the job of the machine and the beamline.The end station A (ESA) at SwissFEL is a dedicated laser pump, x-ray probe setup that is fo-cused on allowing users to perform experiments in the so-called ‘tender’ X-ray regime between 2 keV and 5 keV photon energy. It is meant for x-ray absorption spectroscopy, x-ray emission spectroscopy, x-ray diffuse scattering, and nanocrystallography. Though most of the require-ments for experiments performed in these fields are met by the current design of the end station, new experiments that wish to achieve single-shot reconstructions of nanocrystalline structures and shifts in material properties induced by x-rays have more advanced requirements, one of which is to precisely measure the spectrum of the incoming x-rays for easier and faster data analysis. The tender x-ray spectrometer (TXS) requested here would fulfill that requirement, and be invaluable to users to push the above-mentioned techniques to new frontiers.As every FEL x-ray pulse at SwissFEL is generated from a stochastic process, the spectrum of the pulses changes on a shot-to-shot basis. For experiments that wish to observe the x-ray spectra emitted or reflected by a sample exposed to the non-monochromatized FEL x-ray pulses, the knowledge of the spectrum of the incoming x-ray beam is of greatest importance. The TXS consists of a thin foil of polypropylene, Mylar, polyimide, cyclic olefin copolymer (COC), or cyclic olefin polymer (COP), set up in a vacuum chamber as a scattering target for a von Hamos spectrometer. The von Hamos spectrometer is built with a large concave crystal grating to measure the spectra of the x-rays that elastically scatter off the thin foil, focusing them on a high-speed pixelated x-ray detector, where the spectra are recorded. The spectra are recorded non-destructively as over 80% of the bema is transmitted through the thin foils.