A Study of Jet and Missing Transv erse Ener gy Reconstruction and Data Cleaning Techniques on ATLAS Calorimeter Cosmic Ray Data

Monte Carlo generated QCD jets, and jets reconstructed from cosmic ray data are analyzed and compared. This comparison allo ws some of the rst opportunities to run through a full study , from data collection, to reconstruction, to analysis, within ATLAS, using real events. The ability to handle data at every step of the way will be crucial in achie ving a ìsteady-stateî mode of operation in the coming months and years of ATLAS operation. The use of electromagnetic fractions as a data cleaning technique within the ATLAS calorimeter system is also studied and sho wn to be a rob ust tool in remo ving high ener gy cosmic ray events as a background from jet and E Miss T distributions