Towards the simulation of partially coherent x-ray scattering experiments

Exploiting the coherence properties in the hard X-ray regime is an important topic for the emerging ultra-low-emittance synchrotron storage rings. The Coherent Hard X-ray (CHX) beamline at the National Synchrotron Light Source II (NSLS-II) is exploiting the coherent flux to enable best-in-class time-resolved coherent scattering techniques such as X-ray Photon Correlation Spectroscopy (XPCS) or X-ray Speckle Visibility Spectroscopy (XSVS). Based on the commissioning results, a realistic simulation of the whole beamline, including source and optics, has been performed leveraging a ‘virtual beamline’ module of the ‘Synchrotron Radiation Workshop’ (SRW) code in a web browser based interface to the code named ‘Sirepo’. This virtual beamline capability is used here to simulate partially coherent small angle scattering patterns of samples relevant to the CHX science case, mimicking ‘detector images’ of real experiments. Such source-to-detector simulations of experiments allow for an accurate estimation of feasibility of a given experiment, for an optimization of the beamline setup and interpretation of experimental results.