Counting one-two-three – XPCS experiments with photon counting and integrating detectors
(University of Siegen)
E1.173 (European XFEL)
We present results from XPCS measurements of the glass transition dynamics of an ionic liquid using both a photon counting (Eiger) and an integrating (PN-CCD) X-ray detector. The data has been analyzed with the methodology of quantum optics, such that the speckle contrast is determined through evaluation of the photon statistics. We show the limitations of both types of detectors in terms of a proper assignment of photon numbers detected and discuss the consequences for XPCS experiments at both synchrotron and FEL facilities. The challenge of fast on-line data analysis in high-rep rate XPCS experiments at MID is discussed.