Wuppertal 2015 – scientific programme

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T: Fachverband Teilchenphysik

T 98: Soft QCD und PDF fits

T 98.7: Talk

Thursday, March 12, 2015, 18:15–18:30, K.11.20 (K5)

Determination of the total cross section in proton-proton collisions at the LHC at √s = 8 TeV from elastic scattering using the ALFA sub-detector of ATLAS — •Christian Heinz, Michael Düren, Kristof Kreutzfeldt, and Hasko Stenzel — JLU Giessen

The ALFA (Absolute Luminosity for ATLAS) Roman Pot detector system is part of the forward instrumentation of ATLAS located about 240 m away from the interaction point in the LHC tunnel. ALFA consists of a scintillating fibre tracker housed in vertical Roman Pots which enables the measurement of elastic proton-proton scattering at small scattering angles. In 2012 data were recorded at a centre-of-mass energy of √s = 8 TeV during a fill with special beam optics of the LHC with β^* = 90 m and parallel-to-point focusing.

The four-momentum transfer t is measured for elastically scattered protons and the differential elastic cross section is measured. In this talk a preliminary determination of the total cross section and of the slope of the elastic cross section at small | t | obtained from a fit to the differential cross section using the optical theorem is reported.