Improved luminosity determination in pp collisions at $\sqrt {s} = 7\ \mathrm{TeV}$ using the ATLAS detector at the LHC

The luminosity calibration for the ATLAS detector at the LHC during pp collisions at √s = 7 TeV in 2010 and 2011 is presented. Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the pp collisions at √s = 7 TeV. A luminosity uncertainty of δL/L= ± 3.5 % is obtained for the 47 pb^-1 of data delivered to ATLAS in 2010, and an uncertainty of δL/L= ± 1.8 % is obtained for the 5.5 fb^-1 delivered in 2011.. Authors: Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.. DOE Contract: AC02-05CH11231. Subjects: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS