Today in the afternoon, SASE1 was tuned (a description of the activities in att 4). We now realize that this has in some form changed the SQS pulse parameters.

att 1 shows ion spectra recorded under nominally the same photon parameters before (run 177) and after (run 247)

it's also visible in the history of the SASE viewer that the behavior of the SASE3 pulse energy is different before and after 15:45, which is right when SASE1 was tuned. it clearly started fluctuating more. however, we don't think that the pulse energy fluctuations themselves are the reason for the large change in our data, we rather suspect a change in the pulse duration and/or the source point to cause this. however, we have no means to characterize this now after the fact.

it is particularly unfortunate that the tuning happened exactly BEFORE we started recording a set of reference spectra on the SASE3 spectrometer, which were supposed to serve as a calibration for the spectral corelation analysis to determine the group duration, as well as for a training data set to use the PES with machine learning as a virtual spectrometer for the large data set taken in the shifts before.