A new detector for photon beam position monitoring designed for synchrotron radiation beamlines

For the latest generation of SR sources, local bump orbit feedback systems are being developed for the improvement of the stability of the delivered radiation. The high brightness beamlines using undulator radiation are the most sensitive to electron beam oscillations. Therefore, Photon Beam Position Monitors (PBPM) are being built as detectors of beam movement and as references for feedback systems. The PBPM must not be destructive and has to be suitable for continuous usage. Usual storage ring configurations permit a significant part of the radiation coming from the upstream and downstream dipoles to be superimposed with the undulator radiation. A novel detector, based on spectroscopic techniques, has been developed at ELETTRA. It can be tuned on the working energy of the undulator from a few eV to some keV. A detailed description of the detector layout and its working principle is presented. Its performance with respect to the stability requirements of the beam of synchrotron radiation is also analysed. (C)