Title: Considering the Haystack: The Proton-Proton Inelastic Cross Section Measurement at ATLAS


It is now early 2012 and the LHC is churning out an incredible 25 proton-proton interactions per beam crossing. Experimenters are searching through the mountain-sized haystack of data, hoping to lay hands on nature’s tightly guarded secrets. However, it is worthwhile to consider the billions of unwanted collisions which are ubiquitous, yet poorly understood. These events probe a fundamental, non-perturbative regime of strong interactions which is currently not understood from first principles. In my talk we will return to the spring of 2010 and the early 7 TeV LHC runs. I will describe the first measurement of the inelastic proton-proton cross section at 7 TeV, as well as discuss the results in the context of subsequent proton-proton cross section measurements and cosmic ray physics.