Mainz 2017 – wissenschaftliches Programm
A 3.4: Vortrag
Montag, 6. März 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  calculated by XATOM toolkit . 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.  B.F. Murphy et al., Nat. Commun. 5, 4281 (2014);  S.-K. Son and R. Santra, XATOM - an integrated toolkit for x-ray and atomic physics, CFEL, DESY, Hamburg, Germany, 2011