German Title: Messung des D*+/- Wirkungsquerschnittes im HERMES-Experiment

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Translation of abstract (English)

In this thesis, the production of charm quarks in lepton-nucleon scattering has been investigated. Open charm events are identified through the detection of D^{*+/-} mesons which are produced in the fragmentation of charm quarks. The D^{*+/-} mesons are reconstructed in the decay chain D^{*+} o D^0 pi^+_s o ( K^- pi^+ ) pi^+_s with the Delta M method. The total cross-section for the electroproduction of D^{*+/-} mesons on a proton target has been measured in a fixed target experiment with a lepton beam energy of 27.5 GeV. The analysis is based on data collected by HERMES in 1997. From this result, the open charm photoproduction cross-section is determined for a photon energy of 15.5 GeV. The value for the cross-section is found to be in good agreement with the only other experimental result at similarly low photon energies and does agree with the expectation of perturbative QCD. With the upgrade of the HERMES detector and the large amount of additional data taken in 1998-2000, a first determination of the polarised gluon distribution from open charm production thus seems to be feasible.