Simulation of the ATLAS ALFA detector in comparison with testbeam data

ALFA (Absolute Luminosity for ATLAS) is a scintillating fiber detector for the determination of the absolute luminosity. ALFA con- sists of eight Roman Pots, four on each side of ATLAS at a distance of 240 m. Each detector is made of scintillating fibers with quadratic cross section, glued in UV geometry on ten double sided layers. The detectors are mounted in moveable Roman Pots and can approach the LHC beam up to 1.5 mm, to determine the luminosity from the differential t spectrum of elastically scattered protons using the optical theorem. This is done in special LHC calibration runs with large β ∗ , special focusing and low instant luminosity. The results of ALFA are needed for the calibration of ATLAS luminosity monitors like LUCID. This diploma thesis deals with the simulation of ALFA and the most recent testbeam campaign. A special focus is put on the comparison of results from simulation and testbeam.