What is it about?
We introduce a software tool that evaluates the spectra of a Free-Electron-Laser as they are recorded and calculates an estimation for the current average photon pulse duration (femtoseconds; averaged over the last few hundred shots).
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Why is it important?
Measurement of FEL photon pulse duration is often unavailable or linked to a large experimental effort. Not so the here introduced tool. It can estimate the photon pulse duration whenever high-resolution spectra are recorded, which are at FLASH routinely available at the PG2 beamline. Our spectra-evaluation can help to get an idea of the pulse duration and its fluctuations on a minute-timescale during the experiment. The also available, more in-dept offline statistical-spectral-analysis further provides several common statistical information on previously recorded spectra.
Perspectives
When experimenting with randomly fluctuating light sources like SASE FELs, I feel it to be imperative to have a grasp on the statistical properties of the beam. With our evaluation software, we make a first step into the direction of providing a statistical analysis to users without requiring a much effort and beamtime. Currently, our evaluation software does not provide perfectly accurate results for the absolute pulse duration, but it trumps by its simple availability and the ability to monitor long-term fluctuations. The development of the tools is being continued and I believe that they have the potential to form the basics of a statistical analysis that will be routinely used to provide valuable feedback to operators and experimenters alike during FEL operation.
Mr Robin Yoel Engel
Universitat Hamburg
Read the Original
This page is a summary of: Quasi-real-time photon pulse duration measurement by analysis of FEL radiation spectra, Journal of Synchrotron Radiation, January 2016, International Union of Crystallography,
DOI: 10.1107/s1600577515022997.
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