In this work the properties of scattered protons in the vicinity of the ATLAS
Interaction Point (IP1) for various LHC optics settings are discussed. Firstly,
the beam elements installed around IP1 are presented. Then the ATLAS forward
detector systems: Absolute Luminosity For ATLAS (ALFA) and ATLAS Forward
Protons (AFP) are described and their similarities and differences are
discussed. Next, the various optics used at Large Hadron Collider (LHC) are
described and the beam divergence and width at the Interaction Point as well as
at the ATLAS forward detectors locations are calculated. Finally, the geometric
acceptance of the ATLAS forward detectors is shown and the impact of the LHC
collimators on it is discussed.Comment: 15 pages, 10 figure