Measurement of Charm and Beauty Production in Deep Inelastic Scattering at HERA and Test Beam Studies of ATLAS Pixel Sensors

A measurement of charm and beauty production in Deep Inelastic Scattering at HERA is presented. The analysis is based on the data sample collected by the ZEUS detector in the period from 2003 to 2007 corresponding to an integrated luminosity of 354 pb 1 . The kinematic region of the measurement is given by 5 < Q 2 < 1000 GeV 2 and 0 : 02 < y < 0 : 7, where Q 2 is the photon virtuality and y is the inelasticity. A lifetime technique is used to tag the production of charm and beauty quarks. Secondary vertices due to decays of charm and beauty hadrons are reconstructed, in association with jets. The jet kinematics is dened by E jet T > 4 : 2(5) GeV for charm (beauty) and 1 : 6 < jet < 2 : 2 for both charm and beauty, where E jet T and jet are the transverse energy and pseudorapidity of the jet, respectively. The signicance of the decay length and the invariant mass of charged tracks associated with the secondary vertex are used as discriminating variables to distinguish between signal and background. Dierential cross sections of jet production in charm and beauty events as a function of Q 2 , y , E jet T and jet are measured. Results are compared to Next-to-Leading Order (NLO) predictions from Quantum Chromodynamics (QCD) in the xed avour number scheme. Good agreement between data and theory is observed. Contributions of the charm and beauty production to the inclusive proton structure function, F c c 2 and F b b 2 , are determined by extrapolating the double dierential cross sections using NLO QCD predictions. Contributions to the test beam program for the Insertable B-Layer upgrade project of the ATLAS pixel detector are discussed. The test beam data analysis software package EUTelescope was extended, which allowed an ecient analysis of ATLAS pixel sensors. The USBPix DAQ system was integrated into the EUDET telescope allowing test beam measurements with the front end chip FE-I4. Planar and 3D ATLAS pixel sensors were studied at the rst IBL test beam at the CERN SPS.