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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 8: Diagnostics, Control, Instrumentation

AKBP 8.6: Talk

Thursday, March 23, 2017, 16:15–16:30, MOL 213

Model driven SAXS reconstruction — •Malte Zacharias — HZDR, Dresden, Deutschland — TU Dresden, Dresden, Deutschland

Laser-generated solid density plasmas can be used to produce highly energetic electrons and ions. Diagnosing properties within those plasmas at nm length scales and down to fs time scales plays a crucial role in understanding the involved processes. This has only recently become feasible through the advent of X-Ray Free Electron Lasers (XFELs). XFELs now make experimental techniques like Small Angle X-Ray Scattering (SAXS) applicable to solid density plasmas. As a straight-forward inverse Fourier transform of the SAXS signal is impossible due to lack of phase information, other approaches have to be used. Reconstruction methods like iterative phase retrieval algorithms are an option but in our case do a poor job without strong real space constraints. Our approach is to use parameterized models of the charge density distribution and to adjust their parameters to best fit the resulting simulated SAXS signal to the experimental data. Thus we obtain model information about experimental data in form of the fit parameters. Combining a model with an iterative reconstruction algorithm can be used to automatize the fitting. We present results where this model approach has been applied to a SAXS experiment with structured metal targets that had a well known periodic grating on the surface.