Open AccessNon‐invasive online wavelength measurements at FLASH2 and present benchmark
Author(s) -
Braune Markus,
Buck Jens,
Kuhlmann Marion,
Grunewald Sören,
Düsterer Stefan,
Viefhaus Jens,
Tiedtke Kai
Publication year - 2018
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577517013893
Subject(s) - spectrometer , wavelength , photoelectric effect , data acquisition , laser , optics , computer science , benchmark (surveying) , flash (photography) , physics , geodesy , geography , operating system
At FLASH2, the free‐electron laser radiation wavelength is routinely measured by an online spectrometer based on photoionization of gas targets. Photoelectrons are detected with time‐of‐flight spectrometers and the wavelength is determined by means of well known binding energies of the target species. The wavelength measurement is non‐invasive and transparent with respect to running user experiments due to the low gas pressure applied. Sophisticated controls for setting the OPIS operation parameters have been created and integrated into the distributed object‐oriented control system at FLASH2. Raw and processed data can be stored on request in the FLASH data acquisition system for later correlation with data from user experiments or re‐analysis. In this paper, the commissioning of the instrument at FLASH2 and the challenges of space charge effects on wavelength determination are reported. Furthermore, strategies for fast data reduction and online data processing are presented.