Observation of t Channel Single Top-Quark Production in pp Collisions at $sqrt{s} = 7$~TeV with the ATLAS detector

We report the observation of single top-quark production in the t-channel mode using 156 pb-1 of $pp$ collision data at sqrt(s)=7 TeV recorded with the ATLAS detector at CERN. Selected events contain one lepton, missing transverse energy, and exactly two jets, exactly one of them being identified as coming from a b-quark. We show comparisons of data to a compound background model for kinematic distributions and measure the t-channel production cross section using a cut-based approach and using a multivariate discriminant constructed with a neural network.