  The charm fragmentation function has been measured in D* photoproduction with
the ZEUS detector at HERA using an integrated luminosity of 120 pb-1. The
fragmentation function is measured versus z = (E+p_parallel){D*}/2E{jet}, where
E is the energy of the D* meson and p_parallel is the longitudinal momentum of
the D* meson relative to the axis of the associated jet of energy E{jet}. Jets
were reconstructed using the kT clustering algorithm and required to have
transverse energy larger than 9 GeV. The D* meson associated with the jet was
required to have a transverse momentum larger than 2 GeV. The measured function
is compared to different fragmentation models incorporated in leading-logarithm
Monte Carlo simulations and in a next-to-leading-order QCD calculation. The
free parameters in each fragmentation model are fitted to the data. The
extracted parameters and the function itself are compared to measurements from
e+e- experiments.
