Mainz 2017 – scientific programme

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A: Fachverband Atomphysik

A 3: XUV/X-ray spectroscopy I

A 3.4: Talk

Monday, March 6, 2017, 15:30–15:45, N 2

Calibration of the fluence of an x-ray free-electron laser using XATOM — •Koudai Toyota, Zoltan Jurek, Sang-Kil Son, and Robin Santra — CFEL, DESY, Hamburg

We report on a numerical procedure to calibrate the spatial intensity profile of x-ray free-electron laser pulses (XFELs). Extracting the reliable pulse parameters is indispensable to quantitatively analyze the experimental results and eventually to understand the non-linear physics in matter induced by high intensity XFELs. So far, we have conducted calibrations based on charge state distributions (CSDs) of atomic ions [1] calculated by XATOM toolkit [2]. Such a method has the advantage that the calibration is based on observables directly reflecting the experimental conditions within the interaction volume. By convolving theoretical CSDs with a spatial fluence distribution of a double Gaussian shape profile, which is defined by a few parameters, the experimental CSD was successfully recovered. However, our previous analysis was lacking a comprehensive framework and was manually implemented.

Our new procedure is now built with a well established optimization techniques in numerical analysis and fully automatized via computer codes. Therefore it offers a possibility of deeper investigations based on CSDs over a wide range of a parameter space. We discuss the procedure of optimization algorithms and test different pulse profile ansatz. We demonstrate the workflow and its practical importance on real experimental data. [1] B.F. Murphy et al., Nat. Commun. 5, 4281 (2014); [2] S.-K. Son and R. Santra, XATOM - an integrated toolkit for x-ray and atomic physics, CFEL, DESY, Hamburg, Germany, 2011