Measurement of charm and beauty production in deep inelastic scattering at HERA

In this thesis two measurements of heavy quark production in deep inelastic scattering at HERA are presented. Cross sections for the production of heavy quarks can be calculated in quantum chromodynamics (QCD). The heavy quark masses represent hard scales, which allow to apply perturbative methods. Charm production has been measured with the ZEUS detector using an integrated luminosity of 120 pb-1. The hadronic decay channels D+ → K0Sπ+, Λ+c → pK0S and Λ+c → Λπ+ were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the region pT(D+, Λ+c) < 1.5 GeV. The inclusive cross section and differential cross sections in pT2 (D+), η(D+), Q2 and x for the production of D+ mesons are in reasonable agreement with predictions from perturbative QCD. The fraction of c quarks hadronising into Λ+c baryons was extracted from a combination of both investigated Λ+c decay channels. The result is consistent with a previous measurement in the photoproduction regime and with the average e+e- value. The production of charm and beauty quarks has been measured with the ZEUS detector using the data collected between 2004 and 2007. This data sample corresponds to an integrated luminosity of 354 pb-1. The charm and beauty contents in events with a jet were determined using the decay-length significance and invariant mass of the reconstructed secondary decay vertices. Differential cross sections in EjetT, ηjet, Q2 and x are in reasonable agreement with predictions for perturbative QCD. The open charm and beauty contributions to the inclusive proton structure function F2 were extracted from double differential cross sections in x and Q2. The obtained Fcantic2 and Fbantib2 values are in good agreement with previous measurements and theoretical predictions. This measurement represents the most precise determination of Fbantib2 at the HERA collider in a large part of the accessible phase space. First test beam measurements using the EUDET pixel telescope were performed in 2007 and 2008. Measurements performed at DESY and CERN to estimate the precision of the so-called demonstrator telescope and its sensors are described. The spatial resolution of the full telescope consisting of six MAPS sensors is 1.2 μm. (orig.)