UPGRADES

The FOFB will be extended by an additional DBPM and corresponding adjacent correctors in order to provide proper fast beam steering at the entrance of the in-vacuum undulator which is part of the partially completed FEMTO insertion [9]. In addition to the different corrector magnet design the system integration is of concern since the symmetry of the FOFB layout is broken. As a consequence it is foreseen to introduce 7 DBPMs/sector in order to maintain the present structure where 11 of them remain ``virtual'' for the time being. Recently the synchronous readout of the XBPM blade currents at one of the PX beamlines has been improved to 1 kHz using the existing hardware. The presently uncalibrated horizontal and vertical spectral densities in Fig. 4 document the significant improvement of the photon beam stability up to the 0 dB point with FOFB on. The ``DBPM peak'' at 185 Hz with FOFB on was introduced by a faulty RF front-end of an adjacent DBPM. In the near future all XBPMs will be equipped with readout electronics which will allow their integration into the FOFB loop.

Figure 4: The uncalibrated vertical and horizontal spectral densities taken at the XBPM of a PX beamline document the significant improvement of the photon beam stability up to the 0 dB point with FOFB on (Courtesy: J. Krempaský).