b-Quark Jet Identification for Monitoring ATLAS Performance

Contact:

Michael G. Wilson <>

Context and Motivation

The hadronization of an energetic quark within the Atlas detector leaves energy deposits and particle tracks that may be described collectively as a jet, and the ability to separate light-quark jets from b jets is one of the main features of Atlas. The presence of b jets in an event is a basic signature of many exentensions to the standard model, including supersymmetry and extra dimensions, as well as a handle on standard-model t-quark events. The precise measurements made by the silicon-based tracking detectors are necessary for high-quality b-jet tagging, and the performances of tagging algorithms provide comprehensive metrics for assessing whether the detectors are working optimally or not.

Project Description

This project is to identify and implement a set of time-dependent histograms and graphs for promptly monitoring the performance of b-jet identification in ATLAS data. When colliding-beam data are recorded by the ATLAS detector this fall, these plots will be used to validate and assess their quality to define reliable data sets for physics analyses. These monitoring plots will be of crucial importance at LHC startup, as they will be the first attempt to validate the performance of the ATLAS detector with recorded events from colliding proton beams, and preliminary data sets will be of intense interest to physicists searching for new phenomena.

The student will gain a meaningful introduction to the innermost tracking detectors and the algorithms for identifying b jets, learn how to run ATLAS software to reconstruct and study events, and get experience finding and manipulating ATLAS data. The developments and results of this project will be presented to the ATLAS b-tagging group, and the software will be run with the production reconstruction algorithms. Opportunities for continued work on b tagging, particularly with respect to detailed validation of data and optimization of algorithms for tagging highly boosted b jets, typical in decays of many new hypothetical particles, would follow naturally.