Located at Large Hadron Collider (LHC), ATLAS experiment has been designed with the goal of measuring the products of proton--proton collisions. Although it has full azimuthal angle coverage and large acceptance in pseudorapidity, it is insufficient for some of interactions which can take place in interaction point. Such interactions are for example Central Exlusive Productions. It's product is a central system, which can be measured in ATLAS and two protons scattered at small angles into beam pipe beyond the reach of ATLAS. To fully measure such processes another detector is needed. Therefore ATLAS Forward Proton (AFP) detector was installed.
AFP consists of two stations on both sides of ATLAS, located further than 200 m from interaction point. It is practical to move out stations if they are no longer needed (e.g. in runs with special optics) that is why Roman Pot technology was used for installation allowing to move detectors horizontally. Each Roman Pot station is designed to house Silicon Tracker (SiT) and Time of Flight (ToF) detectors. SiT consists of 4 silicon sensor planes to determine proton kinematics by reconstructing it's trajectory from one station to the other. While ToF detector, created from of 16 L-shaped quartz bars, allows us to reduce pile-up by determining the primary vertex of the two protons by measuring the time of theirs arrival.
This talk is focusing on main features of AFP detector. Roman Pot technology will be explained as well as SiT and ToF structure. In addition performance of SiT planes will be presented and discussed.