PSI-DESY Collaboration Delivers First Photonics Component for SwissFEL

The gas-based photon beam position and intensity monitor is a device originally developed by Dr. Kai Tiedtke and his team at the Deutsches Elektronen-Synchrotron (DESY) for the non-destructive measurement of an X-ray FEL's beam position and flux. The accurate measurement of these variables is necessary due to the stochastic nature of the self-amplified spontaneous emission (SASE) process which can create jitters in the position and flux of the FEL beam on a shot-to-shot basis. The device has been developed and adapted to fit the SwissFEL parameters in a PSI-DESY collaboration over the course of two years. The gas-based detectors, designated as the Photon Beam Intensity Gas (PBIG) monitor and the Photon Beam Position Gas (PBPG) monitor will be the first components to see the photon beam created by the SwissFEL, and will be the main components that users and operators will use to optimize the operations of the machine and to better understand the data collected. The photon beam positon and intensity monitors detect the position and intensity of the FEL beam by counting the number of ions created in a pre-calibrated gas chamber through the photoionization process, and looking at the differences in a split electrode to find the position of the beam. The device boasts the ability to measure relative flux of the FEL beam to a 1% level or better, the absolute flux of the beam to 10% level or better for photon energies ranging up to 20 keV, and can measure the transverse position of the FEL beam to an accuracy of 10 micrometer. The device arrived at PSI at the end of May, and will be one of the first photonics components to be installed in the new SwissFEL facility.