Measurement of the photon identification efficiencies with the ATLAS detector using LHC Run-1 data

F. MONTICELLI; ATLAS

EUROPEAN PHYSICAL JOURNAL C - PARTICLES AND FIELDS

SPRINGER

Lugar: Berlin; Año: 2016

1434-6044

The algorithms used by the ATLAS Collaboration to reconstruct and identify prompt photons are described. Measurements of the photon identification efficiencies are reported, using 4.9 fb−1 of pp collision data collected at the LHC at s√=7   TeV and 20.3 fb−1 at s√=8   TeV . The efficiencies are measured separately for converted and unconverted photons, in four different pseudorapidity regions, for transverse momenta between 10  GeV and 1.5  TeV . The results from the combination of three data-driven techniques are compared to the predictions from a simulation of the detector response, after correcting the electromagnetic shower momenta in the simulation for the average differences observed with respect to data. Data-to-simulation efficiency ratios used as correction factors in physics measurements are determined to account for the small residual efficiency differences. These factors are measured with uncertainties between 0.5% and 10% in 7  TeV data and between 0.5% and 5.6% in 8  TeV data, depending on the photon transverse momentum and pseudorapidity.