Abstract: In order to cope with the occupancy and radiation doses expected at the High-Luminosity LHC, the ATLAS experiment will replace its Inner Detector with an all-silicon Inner Tracker (ITk), consisting of pixel and strip subsystems. In the last two years, several prototype ITk strip modules have been tested using beams of high energy electrons produced at the DESY-II testbeam facility. Tracking was provided by EUDET telescopes. The modules tested are built from two sensor types: the rectangular ATLAS17LS, which will be used in the outer layers of the central barrel region of the detector, and the annular ATLAS12EC, which will be used in the innermost ring (R0) of the forward region. Additionally, a structure with two RO modules positioned back-to-back has been measured, demonstrating space point reconstruction using the stereo angle of the strips. Finally, one barrel and one RO module have been measured after irradiation to 40% beyond the expected end-of-lifetime fluence. The data obtained allow for thorough tests of the module performance, including charge collection, noise occupancy, detection efficiency, and tracking performance. The results give confidence that the ITk strip detector will meet the requirements of the ATLAS experiment.

Abstract: The simulation and analysis of High Energy Physics experiments require a realistic simulation of the detector material and its distribution. The challenge is to describe all active and passive parts of large scale detectors like ATLAS in terms of their size, position and material composition. The common method for estimating the radiation length by weighing individual components, adding up their contributions and averaging the resulting material distribution over extended structures provides a good general estimate, but can deviate significantly from the material actually present. A method has been developed to assess its material distribution with high spatial resolution using the reconstructed scattering angles and hit positions of high energy electron tracks traversing an object under investigation. The study presented here shows measurements for an extended structure with a highly inhomogeneous material distribution. The structure under investigation is an End-of-Substructure-card prototype designed for the ATLAS Inner Tracker strip tracker – a PCB populated with components of a large range of material budgets and sizes. The measurements presented here summarise requirements for data samples and reconstructed electron tracks for reliable image reconstruction of large scale, inhomogeneous samples, choices of pixel sizes compared to the size of features under investigation as well as a bremsstrahlung correction for high material densities and thicknesses.

Abstract: In this paper the results of Edge-TCT and I-V measurements with passive test structures made in LFoundry 150 nm HV-CMOS process on p-type substrates with different initial resistivities ranging from 0.5 to 3 k Omega cm are presented. Samples were irradiated with reactor neutrons up to a fluence of 2.10(15) n(eq)/cm(2). The depletion depth was measured with Edge-TCT. The effective space charge concentration N-eff was estimated from the dependence of the depletion depth on bias voltage and studied as a function of neutron fluence. The dependence of N-eff on fluence changes with initial acceptor concentration in agreement with other measurements with p-type silicon. A long term accelerated annealing study of N-eff and detector current up to 1280 minutes at 60 degrees C was made. It was found that N-eff and current in reverse biased detector behave as expected for irradiated silicon.