Reconstructing a Quark and Gluon Response at ATLAS

Jets, collimated sprays of particles, are the most commonly produced objects in high energy subatomic collisions. Jets are the final state of colliding quarks and gluons. The fraction of a jet's energy that is measured by a calorimeter is called the response. Quark jets (jets initiated by quarks) and gluon jets (jets initiated by gluons) have a different response in the calorimeter. In this thesis the response of quark and gluon jets is reconstructed using jets in dijet and photon + jet events. To measure jet response in dijet events a method is developed to correct the energy of one jet in a dijet event so that it may be used as a reference object in the calibration procedure. The reconstructed dijet, quark and gluon responses are shown to agree with Monte Carlo simulation predictions within their uncertainties.