Measuring the photon background in the LHC experimental environment

Background benchmarking measurements were performed in an experimental set-up comparable to the shielding of ATLAS, a general purpose experiment at the Large Hadron Collider (LHC). The absolute yield and energy measurements of photons emanating from the final stages of the hadronic showers in the shielding were performed with a Be sub 4 Ge sub 3 O sub 1 sub 2 (BGO) detector. Detailed simulations of the set-up were done using the FLUKA code. Comparison between measurements and simulations show that they agree within 20%.