The one-armed ATLAS Forward Proton detector

The ATLAS experiment at the European Laboratory for Particle Physics (CERN), Geneva, has been taking data successfully since the Large Hadron Collider (LHC) accelerator started operations in 2010. Since then, it has been generating proton-proton collisions to study the frontiers of particle physics, at a centre of mass energy of 7-8 TeV first and, more recently, 13 TeV. However, the experiment is in constant evolution: detectors ageing due to radiation damage, increasing collision rates and pile-up, and new scientific objectives often require upgrades of the ATLAS detectors. These ever-growing challenges motivate the continued research and development of new detector technologies. To enhance the physics search of the experiment the ATLAS collaboration recently added a forward detector to identify intact protons that emerge from LHC collisions at very shallow angles. The ATLAS Forward Proton (AFP) detector enables the identification of diffractive processes and, ultimately, of central exclusive events, thus allowing, for example, the search of new heavy resonances in clean events. AFP consists of silicon trackers installed very close to the LHC proton beam and at ~210 m from the interaction point (IP) at each side of ATLAS, in addition to Time-of-Flight detectors for pile-up removal. AFP needs the silicon tracker to fulfil challenging radiation hardness, spatial resolution and active area requirements. The novel 3D pixel sensor technology, first employed in the ATLAS Insertable B-Layer, was further developed and qualified for AFP. The “one-armed AFP detector”, on which this thesis is focused, refers to the stage in which the AFP detector consisted only of silicon trackers in one side of ATLAS, installed at the beginning of 2016. The full installation was successfully finished one year later, when both silicon trackers and Time-of-Flight detectors were installed in both sides of ATLAS. This thesis describes the full process of technology characterization of the silicon tracker, production, installation, operation and particle physics data analysis of the one-armed AFP detector.