  The LHCb Outer Tracker is a gaseous detector covering an area of 5x6 m2 with
12 double layers of straw tubes. The detector with its services are described
together with the commissioning and calibration procedures. Based on data of
the first LHC running period from 2010 to 2012, the performance of the readout
electronics and the single hit resolution and efficiency are presented. The
efficiency to detect a hit in the central half of the straw is estimated to be
99.2%, and the position resolution is determined to be approximately 200 um.
The Outer Tracker received a dose in the hottest region corresponding to 0.12
C/cm, and no signs of gain deterioration or other ageing effects are observed.
