Physics prospects with the ALFA and AFP detectors

We will describe the experimental challenge presented by the measurement of the forward protons at the LHC. The ATLAS ALFA and AFP projects involve the deployment of detectors capable of detecting protons that emerge intact from the interaction with very small scattering angles. In the case of the ALFA detector, located at $\pm${240}~m from the ATLAS interaction point, this measurement has to be performed using special high $\beta^*$ beam optics. The detector chosen for the task is a nearly edgeless scintillating fibre tracker capable of making measurements at very low $t$ - below $10^{-3} \text{GeV}^2$ - in the Nuclear Coulomb interference region. In order to reach these very small $t$ values we need to deploy the detector very near to the beam line utilizing Roman Pots. The main purpose of the ALFA detector is to measure the total p-p cross-section, a fundamental quantity in hadronic physics of importance to particle and to cosmic ray physicists and to provide absolute measurement of luminosity which includes eventual measurements of dependency of nuclear slope $\textit{b}$ and $\rho$ parameters on $\textit{t}$. Another capability of ALFA detector is measurement of soft diffraction and some exclusive processes. The main purpose of the AFP detector is to measure exclusive physics processes and anomalous couplings. The AFP detectors are placed at $\pm$204 and $\pm$212~meters on both side of the ATLAS experiment giving ATLAS the remarkable capability to tag and measure, with 3-D silicon detectors, both protons in exclusive central diffractive processes. The use of precision timing detectors allows this type of physics to be pursued to high luminosity for the first time. The AFP project opens up an important new window on LHC physics not available with the standard ATLAS detector. In this talk the experimental challenges in constructing this detector as well as the status of the project will be discussed.