AFP - ATLAS Forward Proton project

The ATLAS Forward Proton (AFP) project promises a significant extension to the physics reach of ATLAS by tagging and measuring the momentum and emission angle of very forward protons. This enables the observation and measurement of a range of processes where one or both protons remain intact which otherwise would be difficult or impossible to study. Such processes are typically associated with elastic and diffractive scattering, where the proton radiates a virtual colorless “object,” the so-called Pomeron, which is often thought of as a non-perturbative collection of soft gluons.

Diffractive protons are usually scattered at very small angles (hundreds of micro radians). In order to measure them, special devices that allow for the detector movement (so-called Roman pots, RP) are commonly used. The ATLAS Forward Proton (AFP) are placed symmetrically with respect to the ATLAS IP at 204 m and 217 m. Stations located closer to the IP contain the tracking detectors, whereas the further ones are equipped with tracking and timing devices. The reconstruction resolution of tracking detectors is estimated to be of 10 and 30 μm in x and y, respectively. The precision of Time-of-Flight measurement is expected to be of about 20 ps.