Abstract submitted to the
         XXXth International Conference on High Energy Physics
                July 27 - August 2, 2000, Osaka, Japan
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      Measurement of inclusive Ds+- photoproduction at HERA

                    
                               ZEUS Collaboration





                                    Abstract



      The first measurement of inclusive Ds+- photoproduction at
      HERA has been performed with the ZEUS detector for photon-proton
      centre-of-mass energies 130 < W < 280 GeV. The measurements are 
      compared with inclusive D*+- photoproduction cross sections in 
      the same kinematic region and with QCD calculations. The ratio
      of Ds+- to D*+- cross sections has been determined and used to
      extract the strangeness-suppression factor in charm photoproduction
      within the LUND string fragmentation model. The results are in 
      good agreement with those obtained from charm production in e+e-
      annihilation.