Silicon Strip Detectors for the ATLAS HL-LHC Upgrade

While the Large Hadron Collider (LHC) at CERN is continuing to deliver an ever-increasing luminosity to the experiments, plans for an upgraded machine called High Luminosity LHC (HL-LHC) are progressing. The upgrade is foreseen to increase the LHC design luminosity up to 5 x 1034 cm-2 s-1. The ATLAS experiment will need to build a new tracker for HL operation, which would cope with the increase in pile-up backgrounds at the higher luminosity. A new generation of extremely radiation hard silicon detectors is being designed. Silicon sensors with sufficient radiation hardness are the subject of an international R&D programme, working on pixel and strip sensors. The efforts presented here concentrate on the innermost strip layers. We have developed a large number of prototype planar detectors produced on p-type wafers in a number of different designs. The irradiated sensors were subsequently tested in order to study the radiation-induced degradation, and determine their performance after irradiation of up to a few 1015 1-MeV equivalent neutrons/cm2. In this paper, it is reported an overview of the ATLAS tracker upgrade project, in particular focusing on the crucial innermost silicon strip layers. Results from a wide range of irradiated silicon detectors and layout concepts are presented.