Thesis defense [before December 2013]

Licentate Thesis: Signal Reconstruction in the ATLAS Tile Calorimeter and Backgrounds to Supersymmetry

by Maja Tylmad (Fysikum)

Europe/Stockholm
A4:1003

A4:1003

Description
The ATLAS detector at CERN is currently recording data from proton-proton collisions at √s=7 TeV, the highest energy collisions produced in a controlled environment. The detector is designed to study the smallest building blocks of matter and their fundamental interactions. ATLAS can also provide insight to the laws of physics into an energy regime never studied before. Supersymmetry postulates the existence of a number of new particles with masses around 1 TeV, thus reachable with the LHC. Supersymmetric signals in ATLAS may include missing transverse energy, a number of jets and final state leptons. Paper I describes a method to determine the background from fake isolated muons when searching for supersymmetry. Measurement of the energy of hadronic jets is important both to Standard Model physics and to discovering new physics. To obtain an accurate energy measurement of hadronic jets a precise knowledge of the pulse-shapes from the hadron calorimeter is required. Paper II describes a study of the pulse-shapes in the ATLAS Tile Calorimeter performed in test-beam data. Paper III describes the measurement of these shapes using the entire ATLAS Tile Calorimeter and proton-proton collisions.