ATLAS Inner Detector Studies with Photon Conversions

With the start of LHC operations at 7TeV copious production of photons with a wide energy spectrum is expected, not least from the decay of minimum bias pi0 mesons into two photons. Due to the large amount of material that they will traverse before the reach the ATLAS electromagnetic(EM) calorimeter, ~50% of these photons will convert on average. These converted photons can provide us with the means of mapping the material of the ATLAS tracker in front of the EM calorimeter. In this talk we report on the results of the measurement of the amount of the ATLAS tracker material with the help of accurately measured reference surfaces inside the tracker. Finally results from using the extremely pure electron sample provided by the converted photons to study the particle identification capabilities of the ATLAS Transition Radiation Tracker (TRT), are presented. We also touch on material studies using energy flow in the EM calorimeter as well as stability of the KS mass.