• clean events
• top mass

This thesis describes a new measurement of the top quark mass by analyzing specially selected events produced in proton-antiproton collision at the Fermilab Tevatron Collider (Batavia, USA) at center of mass energy 1.96 TeV and collected by the Collider Detector at Fermilab (CDF).
The candidate presents in this work a measurement of the mass of the top quark made by reconstructing top-antitop pairs through the lepton+jets decay channel and implementing the Top Mass Template Method.
Results are presented from a data sample of integrated luminosity of 2fb-1 developing a new selection on the pretag lepton+jets sample, named “clean selection“.
This is a kinematical selection based on jet shape analysis. In this way it is possible to reduce the contribution of events with jets due to gluon radiation. Since the major source of error in the top mass measurement is due to wrong jet-to-parton assignments the clean selection combined to the request of exactly 4 jets in the event is found as expected to reduce the Final State Radiation (FSR) and Initial State Radiation (ISR) contributions to the uncertainty.