3D detectors for the High Luminosity LHC, with a feasibility study into the observation of $ZZ$ production in the $Z$→ee/μμ ,$Z$→ττ channel with the ATLAS detector

This thesis presents three bodies of work related to the ATLAS detector and physics measurements at the high luminosity frontier. The first investigates the use of 3D silicon detectors at the High Luminosity LHC. Several sensors are irradiated up to a fluence equal to that expected in the ATLAS pixel detector layers, and tests into their radiation tolerance performed. The second continues along a similar theme and pertains to the application of the 3D principle in an intrinsically more radiation tolerant material – diamond. The fabrication and testing of the first prototype 3D diamond detector for the purpose of particle tracking is described. The final body of work moves away from the imperative technical work required with increased luminosity, to the potential gains in physics analysis. The feasibility of observing rare di-boson $ZZ$ events in which one $Z$→ee/μμ and the other $Z$→ττ, in data taken by the ATLAS detector is detailed. In addition to an increased luminosity, this analysis is likely to benefit from future upgrades to the pixel detector.