A measurement of the total pp cross section at the LHC at √s = 8 TeV is presented. An integrated luminosity of 500 μb−1 was accumulated in a special run with high-β⋆ beam optics to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the −t range from 0.014 GeV2 to 0.1 GeV2 to extrapolate t→0, the total cross section, σtot(pp→X), is measured via the optical theorem to be σtot(pp→X) = 96.07 ± 0.18(stat.) ± 0.85(exp.) ± 0.31(extr.)mb, where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation t→0. In addition, the slope of the exponential function describing the elastic cross section at small t is determined to be B = 19.74 ± 0.05(stat.) ± 0.23(syst.) GeV−2.
Aaboud, M., Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Abeloos, B., et al. (2016). Measurement of the total cross section from elastic scattering in pp collisions at √s = 8 TeV with the ATLAS detector. PHYSICS LETTERS. SECTION B, 761, 158-178 [10.1016/j.physletb.2016.08.020].