Refined reconstruction and calibration of the missing transverse energy in the ATLAS detector

We describe a refined reconstruction and calibration of missing transverse energy (Etmiss) developed by ATLAS and tested on events containing Z and W bosons. The data sample was collected in proton-proton collisions at a center-of-mass energy of 7 TeV, and corresponds to an integrated luminosity of about 36 pb-1. Z ->l+l- events are used to evaluate the algorithm performance in the absence of any significant Etmiss. In W->ln u events, the refined reconstruction is studied in events containing genuine Etmiss originating from the neutrino. A preliminary estimate of the systematic uncertainty on the Etmiss scale is presented.