Optimization of X-ray beam position monitor for a segmented figure-8 undulator beamline at SPring-8

A soft X-ray undulator beamline BL07LSU has been constructed in the 27m long straight section of the SPring-8 storage ring for researching on advanced soft X-ray spectroscopy material science. The light source consists of eight figure-8 undulator segments (four horizontal and four vertical polarization segments) and seven phase shifters. In BL07LSU the four-blade-drive style, which can drive each detector head independently, has been introduced as a X-ray beam position monitor (XBPM), because the light source of BL07LSU produces various synchrotron radiation beam profiles. But then, the water-cooled absorber chamber has been installed in the storage ring in order to prevent irradiating components of the storage ring by skirt of synchrotron radiation beam profile, and temperature rising. The beam profile in a vertical direction has been restricted by an aperture of the absorber chamber. The XBPM, which is placed under such special condition, has been optimized in consideration of observation and calculation results of the beam profile. (author)