Author: Mueller, R.     [Müller, R.]
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WEPOW011 BESSY II Supports an Extensive Suite of Timing Experiments 2840
  • R. Müller, T. Birke, F. Falkenstern, K. Holldack, P. Kuske, A. Schälicke, D. Schüler
    HZB, Berlin, Germany
  • H.G. Glass, R. Ovsyannikov
    BESSY GmbH, Berlin, Germany
  The synchrotron light source facility BESSY II has put top-up and a fast orbit feedback (FOFB) into operation in 2013. Both operational improvements have matured and turned out to be especially beneficial for the advanced timing opportunities supported at BESSY. In combination with very tight injection efficiency requirements a thorough understanding of top-up injections under all operational conditions has been developed. Consequently arbitrary bunch currents can be dialed in and maintained on demand. In standard mode, a very pure camshaft bunch is available both in general for laser pump/X-ray probe and for pseudo single bunch experiments at the MHz chopper beamline. 3 constant high current bunches support the FEMTOSPEX slicing facility. An additional bunch can be resonantly excited and pulse picked via custom orbit bumps at 3 different undulator beamlines (PPRE). Due to the FOFB the classical timing modes "single bunch" and "low alpha" feature an attractive pointing stability.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW011  
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THPOW039 Measurements of the Lattice Modifications for the Cryogenic Undulator CPMU17 4031
  • J. Bahrdt, D.B. Engel, W. Frentrup, P. Goslawski, P. Kuske, R. Müller, M. Ries, M. Ruprecht, A. Schälicke
    HZB, Berlin, Germany
  A 2 mrad-canted double undulator system is in preparation as the wide energy range light source for the Energy Material in-situ Laboratory EMIL at the HZB storage ring BESSY II. The cryogenic undulator CPMU-17 is the hard X-ray device of the double undulator system. The soft X-ray undulator UE-48 is of the APPLE II type. It was installed and commissioned a few months ago, whereas the CPMU-17 is under fabrication. The CPMU-17 will employ a minimum magnetic gap of 5.5mm. Including a CuNi-foil for RF-shielding and geometric tolerances the free aperture is planned to be 5.0 mm. The BESSY II lattice has been modified locally in order to cope with the small gap device. The adapted betatron functions with a shifted vertical beam waist were measured and fitted with LOCO. The new optics agrees with the predicted performance. The free aperture at the installation place of the CPMU-17 was measured with four vertical scrapers. It is compatible with the projected minimum undulator gap. Finally, the measured injection efficiency with the new EMIL optics switched on is compatible with top-up operation (injection efficiency ≥ 90 %).  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW039  
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