Studies on irradiated pixel detectors for the ATLAS IBL and HL-LHC upgrade

The constant demand for higher luminosity in high energy physics is the reason for the continuous effort to adapt the accelerators and the experiments. The upgrade program for the experiments and the accelerators at CERN already includes several expansion stages of the Large Hadron Collider (LHC) which will increase the luminosity and the energy of the accelerator. Simultaneously the LHC experiments prepare the individual sub-detectors for the increasing demands in the coming years. Especially the tracking detectors have to cope with fluence levels unprecedented for high energy physics experiments. Correspondingly to the fluence increases the impact of the radiation damage which reduces the life time of the detectors by decreasing the detector performance and efficiency. To cope with this effect new and more radiation hard detector concepts become necessary to extend the life time. This work concentrates on the impact of radiation damage on the pixel sensor technologies to be used in the next upgrade of the ATLAS Pixel Detector as well as for applications in the ATLAS Experiment at HL-LHC conditions. The sensors considered in this work include various designs based on silicon and diamond as sensor material. The investigated designs include a planar silicon pixel design currently used in the ATLAS Experiment as well as a 3D pixel design which uses electrodes penetrating the entire sensor material. The diamond designs implement electrodes similar to the design used by the planar technology with diamond sensors made out of single- and poly-crystalline material. To investigate the sensor properties characterization tests are performed before and after irradiation with protons or neutrons. The measurements are used to determine the interaction between the read-out electronics and the sensors to ensure the signal transfer after irradiation. Further tests focus on the sensor performance itself which includes the analysis of the leakage current behavior and the charge collection properties. The sensor responds to the passing of a charged particle are measured with radioactive sources and particle beams of electrons and pions. To conclude the sensor research the accomplished development stages of the IBL upgrade of the ATLAS pixel detector foreseen for 2013/2014 are summarized. This includes among other things, the progress of the quality assurance process as well as the production of a first stave prototype used to test the stave production process.