The ATLAS Tracker Upgrade: Short Strips Detectors for the SLHC

It is foreseen to increase the luminosity of the Large Hadron Collider (LHC) at CERN around 2018 by about an order of magnitude, with the upgraded machine dubbed Super-LHC or sLHC. The ATLAS experiment will require a new tracker for SLHC operation. In order to cope with the order of magnitude increase in pile-up backgrounds at the higher luminosity, an all silicon detector is being designed. The new strip detector will use significantly shorter strips than the current SCT in order to minimise the occupancy. As the increased luminosity will mean a corresponding increase in radiation dose, a new generation of extremely radiation hard silicon detectors is required. A massive R&D programme is underway to develop silicon sensors with sufficient radiation hardness. New front-end electronics and readout systems are being designed to cope with the higher data rates. The challenges of powering and cooling a very large strip detector will be discussed. Ideas on possible schemes for the layout and support mechanics will be shown. A key issue for the upgrade is the development of silicon sensors with sufficient radiation hardness for the pixel and strip layers. We have developed planar detectors to be made on p-type wafers in a number of different designs. These prototype detectors were then produced by a leading manufacturer and irradiated to a set of fluences matched to sLHC expections. The irradiated sensors were subsequently tested wit h LHC-readout-electronics in order to study the radiation-induced degradation, and determine their performance after serious hadron irradiation of up to 1015 Neutron-equivalent. The signal suffers degradation as a function of irradiation. It is however evident that sufficient charge can still be recorded even at the highest fluence. We will give an overview of the ATLAS tracker upgrade, in particular focusing on innermost silicon strip layers. Results from a wide range of irradiated silicon detectors will be presented. We will draw conclusions on what type and design of strip detectors to employ for the upgrades of the tracking layers in the sLHC upgrades of LHC experiments.