Pulse energy measurement at the SXR instrument

A gas monitor detector was implemented and characterized at the Soft X-rayResearch (SXR) instrument to measure the average, absolute and pulse-resolved photon flux of the LCLS beam in the energy range between 280 and2000 eV. The detector is placed after the monochromator and addresses theneed to provide reliable absolute pulse energy as well as pulse-resolvedmeasurements for the various experiments at this instrument. This detectorprovides a reliable non-invasive measurement for determining flux levels on thesamples in the downstream experimental chamber and for optimizing signallevels of secondary detectors and for the essential need of data normalization.The design, integration into the instrument and operation are described, andexamples of its performance are given