Insertable B-Layer integration in the ATLAS experiment and development of future 3D silicon pixel sensors

This work has two distinct objectives: the development of software for the integration of the Insertable B-Layer (IBL) in the ATLAS offline software framework and the study of the performance of 3D silicon sensors produced by SINTEF for future silicon pixel detectors. The former task consists in the implementation of the IBL byte stream converter. This offline tool performs the decoding of the binary-formatted data coming from the detector into information (e.g. hit position and Time over Threshold) that is stored in a format used in the reconstruction data flow. It also encodes the information extracted from simulations into a simulated IBL byte stream. The tool has been successfully used since the beginning of the LHC Run II data taking. The experimental work on SINTEF 3D sensors was performed in the framework of the development of pixel sensors for the next generation of tracking detectors. Preliminary tests on SINTEF 3D sensors showed that the majority of these devices suffers from high leakage currents, low breakdown voltages and short charge carrier lifetimes. These signs of production issues were identified, during the subsequent prototyping run, as random doping deposition caused by a too-thin masking layer. The sensors underwent proton or neutron irradiation (up to $\phi = 9\cdot 10^{15}\ \text{n}_{\text{eq}}/\text{cm}^{2}$) to allow for fluence-dependent characterisation. Electrical measurements and charge collection measurements under laser or radioactive source exposure have been carried out. Results of the electrical tests highlight a significant and sensor-dependent spread of these parameters. Common traits can however be identified: the leakage current augments as expected with temperature and with fluence. Radiation does not affect the depletion voltage, which remains at $U_{depl} \leq 20\ \text{V}$. The breakdown voltage is observed to increase with fluence. Laser-induced charge collection measurements, performed using a TCT setup, show that sensors with diode-like electrical properties collect, even when irradiated at higher fluences, a larger and more uniform charge compared to sensors featuring suboptimal electrical characteristics. Radioactive source tests have been performed using an ALiBaVa read-out system. Results show that the SINTEF 3D sensor proton-irradiated to $\phi= 4.5 \cdot10^{14}\ \text{n}_{\text{eq}}/\text{cm}^{2}$ maintains a charge collection efficiency of 85% at $U_{bias} = -40\ \text{V}$. Experimental results support the findings observed during the latest SINTEF prototype run. Moreover, the three characterisation methods give consistent results. The electrical characterisation is therefore sufficient to identify suboptimallyperforming sensors.