Overview of ATLAS Forward Proton Detectors for LHC Run 3 and Plans for the HL-LHC

A key focus of the physics program at the LHC is the study of head-on proton-proton collisions. An important class of processes that can be studied are ones where protons remain intact. In such cases the electromagnetic fields surrounding the protons can interact producing high energy photon-photon collisions, for example. Alternatively, interactions mediated by the strong force can also result in intact forward scattered protons, providing probes of quantum chromodynamics (QCD). In order to aid an identification and provide a unique information about these interactions, in- strumentation to detect and measure protons scattered through the very small angles is installed in the beam-pipe far downstream of the interaction point. In this paper, the description of the ATLAS Roman Pot Detectors (AFP and ALFA), their performance to date and expectations for the upcoming LHC Run 3 will be discussed. The physics of interest, beam optics and detector options for the extension of the programme into the High-Luminosity LHC (HL-LHC) era are also discussed.