Master thesis defense by Mike Lauge

Title: dE / dx Measurements in the ATLAS Detector

The ATLAS Pixel detector is able to provide a measurement of the specific energy loss dE/dx for tracks from proton-proton collisions at high center of mass. This thesis defense will present a study of the this measurement and evaluate if cuts stated in earlier studies (2011) are still needed, or if the upgrades made to the Pixel Detector have resulted in needed adjustments to the cuts. The study introduce a new method of calculating the dE/dx of a track. This is done by using the knowledge of the distribution of dE/dx to likelihood fit the hits of the individual track.

In additions to this a study of the dependency of dE/dx on β is completed, showing that the dependency fulfill as simplification of the Bethe-Bloch formula. In addition, a study on the uncertainty of β, which indicates a correlation between increasing uncertainty as the value of dE/dx increases, will be covered.