Multijet Background Estimation for Supersymmetry Searches Using the ATLAS Detector at the Large Hadron Collider

This thesis describes a data-driven technique for estimating the multijet background to Supersymmetry (SUSY) searches with no leptons using the ATLAS detector at the Large Hadron Collider. The technique is used to estimate multijet distributions in SUSY signal and control regions with 1 fb−1 of sqrt(s) = 7 TeV data collected by ATLAS in 2011. The systematic uncertainty on the estimates is reduced with the development and use of novel event shape triggers. Multijet estimates provided from the technique developed in this thesis are used by the ATLAS collaboration in several different SUSY searches.