B-physics potential of the ATLAS experiment and performance of the ATLAS Transition Radiation Tracker

The ATLAS experiment is one of the four experiments at the Large Hadron Collider (LHC), which is supposed to be operational in early 2007. Proton-proton collisions at an unprecedented center-of-mass energy of 14 TeV will probe new frontiers of the universe, hopefully providing a better understanding of the laws governing our universe. Although the ATLAS detector has been optimized to search for the Higgs boson within the full expected mass range and other new particles, it is well adapted to cover a wide range of B-physics topics. The determination of the angles of the Unitarity Triangle, and measurements of CP violation are also a key point for a full and coherent understanding of the fundamental forces governing the universe. Intriguing particles, such as the $
m{B_{c}}$ meson, provide a very interesting case to study the interplay of strong and weak interactions, a key problem in the theoretical analysis of the weak decays of hadrons. The Transition Radiation Tracker (TRT) is a combined straw drift tube and transition radiation detector. It provides a combination of continuous tracking with many projective measurements based on individual drift tubes and of a powerful electron identification based on radiator fibers or foils interleaved with the straws. An extensive program of tests undertaken on several small scale prototypes has shown a good and satisfactory performance.