Development and simulation of 3D diamond detectors

Ever increasing demand for more radiation resistant detectors from experiments such as those at the Large Hadron Collider has pushed the development of novel radiation resistant technologies. Recent developments in the laser processing of diamond have led to the construction of the first 3D diamond detectors: diamond detectors with graphitic electrodes embedded in the sensor material bulk rather than on the surface. This technology also presents interesting properties for the medical field, where 3D diamond detectors are also of interest. This thesis details some of the steps that were carried out between the fabrication of some of the first 3D diamond devices to the present day production and testing of the first 3D pixel devices and the first use of 3D diamond devices in Particle Physics experiments. This progress has in part been pushed by improvements in the laser processing techniques allowing the production of columns with lower resistances and more consistent properties. This thesis describes the fabrication of a number of these devices and details the experiments that these devices have undergone in a number of different conditions at the Diamond Light Source (Oxford), the Ruder Boskovic Institute (Zagreb), the Paul Scherrer Institute (Zurich), and the test beam facilities at CERN. This thesis also describes the simulations that were carried out to replicate the data obtained from some of the earlier devices, and hence understand how charge is collected in 3D diamond detectors and to explain some of the observed behavior of these devices

Timing optimization for 3D silicon sensors

Looking forward to future High Luminosity LHC experiments, efforts to develop new tracking detectors are increasing. A common approach to improve track reconstruction efficiency in high pile-up conditions is to add time measurement per pixel with resolution smaller than 50 ps. Different sensor technologies are under development in order to achieve those performances, like low gain avalanche diodes and 3D sensors. 3D sensors are characterized by very fast charge collection times, but present some critical issues in timing due to their electrode configurations. The presence of zero electric field volumes inside the electrodes themselves and low electric field regions between same sign electrodes causes that the 3D sensor technology presents potentially a large time walk contribution which negatively affects time resolution. In order to reduce this error drastically, a detailed study based mostly on simulation has been done with main focus on the exploration for a timing optimized 3D sensor electrode configuration. To have a more detailed view of the timing performances, sensor operation was also simulated, using TCAD and other simulation tools developed specific for this application, and the results analysed. In this presentation a detailed overview of the modelling and simulation activity as well as their results, including also future steps will be presented. The output of this studies defines the optimal sensor layout for timing applications

Measurement of the W±ZW^{\pm}Z boson pair-production cross section in pppp collisions at s=13\sqrt{s}=13 TeV with the ATLAS Detector

The production of $W^{\pm}Z$ events in proton--proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb$^{-1}$. The $W^{\pm}Z$ candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is $\sigma_{W^\pm Z \rightarrow \ell^{'} \nu \ell \ell}^{\textrm{fid.}} = 63.2 \pm 3.2$ (stat.) $\pm 2.6$ (sys.) $\pm 1.5$ (lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is $53.4^{+3.6}_{-2.8}$ fb. The extrapolation of the measurement from the fiducial to the total phase space yields $\sigma_{W^{\pm}Z}^{\textrm{tot.}} = 50.6 \pm 2.6$ (stat.) $\pm 2.0$ (sys.) $\pm 0.9$ (th.) $\pm 1.2$ (lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of $48.2^{+1.1}_{-1.0}$ pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent $W^+Z$ and $W^-Z$ cross sections and their ratio