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{\bf Abstract Registration Number 538} \\
{\bf Parallel sessions: 4,7} \\
{\bf Plenary sessions: 6,9}
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\abstractheader{\bf Determination of the Gluon Density in the Proton from Charm \\
Electro- and Photo-Production at HERA Using NLO QCD\\
H1 Collaboration, DESY}

\abstractbody{
With the H1 detector at the $ep$ collider HERA, $D^*$ meson production
cross sections have been measured in deep inelastic scattering with
4-momentum transfers $Q^{2}>2$~GeV$^2/$c$^2$ and in photo-production
at photon-proton centre-of-mass energies $W_{\gamma p} \approx 88$
and $194$~GeV. Next-to-leading order QCD calculations are found to describe
the differential cross sections well. Using these calculations, the gluon
momentum distribution in the proton, $xg(x)$, has been extracted in the 
momentum fraction range $7.5 \cdot 10^{-4} < x < 4 \cdot 10^{-2}$,
at average scales $\mu ^{2} = 25$ to $50$~GeV$^2/$c$^2$. The gluon
momentum fraction $x$ has been approximately reconstructed from the
measured kinematics of the scattered electron and the $D^*$ meson 
in the final state.
}

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