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Figure 9
Uncertainty of the absolute cross-section measurement for different sources of error (%) related to the spectrometer. The photon-noise-induced fractional error of the undulator envelope is shown in green, the jitter error on top in purple, and at FWHM in blue. The 1σ dispersion of the collected data is superimposed on the trace. The principal source of error originates from the jitter effect and increases as we move away from the top of the undulator envelope. In order to minimize this effect, and when a large spectral range has to be covered, the stitching of the spectral windows is performed typically at half-maximum of the undulator envelope. |