SMuK 2023 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 28: Forward Physics

T 28.3: Vortrag

Dienstag, 21. März 2023, 17:30–17:45, HSZ/0101

Obtaining the Total Cross-Section and ϱ-Parameter from Elastic Proton-Proton Scattering at √s = 900 GeV with the ATLAS Subdetector ALFA — Wolfgang Friebel², Karlheinz Hiller², •Mustafa Schmidt¹, and Hasko Stenzel³ for the ATLAS collaboration — ¹Bergische Universität Wuppertal — ²Deutsches Elektronen-Synchrotron DESY — ³Justus-Liebig-Universität Gießen

ALFA (Absolute Luminosity for ATLAS) is a Roman Pot (RP) detector system in the LHC tunnel, located around 240 m away from the Interaction Point (IP) downstream in the forward region of ATLAS. The ALFA subdetector contains several layers of scintillating fibers for tracking elastically scattered protons in the outgoing beams. The RPs are used as a housing for the fiber trackers and can be moved in small steps close to the beam to ensure proton tracking at small scattering angles. In 2018, 12 runs were recorded at a center-of-mass energy of √s = 900 GeV during several fills using special LHC beam optics with β^⋆= 100/50 m parallel-to-point focusing.

This combination makes it possible to probe various important physics parameters of pp interactions in the Coulomb-nuclear interference region, providing a unique evaluation of the underlying model predictions within the non-perturbative QCD regime. A fit describing the physics models to the elastic cross-section distribution, which is obtained from the calculation of the four-vector momentum transfer, allows the extraction of the nuclear slope parameter B, the total cross-section σ, and the ϱ-parameter, defined as ϱ = ℜ[f(0)]/ℑ[f(0)]. This talk covers the current status of the ongoing analysis and future steps.