• J. Keil, K. Balewski
  DESY, Hamburg

PETRA III is a 6 GeV third generation light source located at DESY/Hamburg. The former pre-accelerator of HERA has been converted in 2007/2008 into a high brilliance synchrotron light source with an emittance of 1 nm*rad. The commissioning of PETRA III started in 2009. PETRA III is like other third generation light sources very sensitive to errors of the linear optics. Gradient errors reduce the dynamic aperture, increase the emittance and change the beam size. The correction of the optics is based on orbit response matrix data which were analyzed both with the program LOCO and with a fit of the beta-functions and phase-functions at BPMs and correctors. Initial results of the modelling of the machine and the correction of the linear optics functions will be presented.

• G.K. Sahoo, K. Balewski, W. Decking, J. Keil
  DESY, Hamburg

PETRA III is a 6GeV positron light source with a design horizontal beam emittance of 1nm.rad and 1% emittance coupling. This low emittance is achieved with proper correction of horizontal dispersion to its theoretical values in the arcs as well as dispersion free sections. The spurious vertical dispersion, arising due to misalignment and rotational errors of the magnets is also duly corrected as this contributes to the vertical beam size of the photon beam. Here we discuss the method taken to correct the horizontal dispersion using a combined orbit and dispersion correction scheme. In the vertical plane the same procedure can be used as that of horizontal plane or only the dispersion can be corrected using dedicated skew quadrupoles to millimeter level after orbit correction has been done. In this paper we present the methods used and results obtained in correction of dispersions in transverse planes.