Novel applications of the x-ray tracing software package McXtrace

We will present examples of applying the X-ray tracing software package McXtrace to different kinds of X-ray scattering experiments. In particular we will be focusing on time-resolved type experiments. Simulations of full scale experiments are particularly useful for this kind, especially when they are performed at an FEL-facility.

Beamtime here is extremely scarce and the delay between experiment and publication is notoriously long. A major cause for the delay is the general complexity of the experiments performed. A complexity which arises from the pulsed state of the source. As an example, consider a pump-and-probe type experiment.

In order to get the wanted signal from the sample the X-ray pulse from the FEL source needs to overlap in space and time with the pumping pulse inside the sample. This is made more difficult by several effects: The sample response may be dependent of the polarisation of the pumping and/or probing pulse.

There may be significant time-jitter in the pulse arrival times. The composition of the sample may vary depending on local sample geometry and be modified by the probing pulse. Many of the samples considered are in a liquid state and thus have a variable geometry. ...to name some of the issues encountered.

Generally more than one or all of these effects are present at once. Simulations can in these cases be used to identify distinct footprints of such distortions and thus give the experimenter a means of deconvoluting them from the signal. We will present a study of this kind along with the newest developments of the McXtrace software package.