Upgrade of the ATLAS Silicon Tracker for the sLHC

While the CERN Large Hadron Collider (LHC) will start taking data this year, scenarios for a machine upgrade to achieve a much higher luminosity are being developed. In the current planning, it is foreseen to increase the luminosity of the LHC at CERN around 2016 by about an order of magnitude, with the upgraded muchine dubbed Super-LHC or SLHC. As radiation damage scales with integrated luminosity, the particle physics experiments at the SLHC will need to be equipped with a new generation of radiation-hard detectors. This is of particular importance for the semiconductor tracking detectors located close to the LHC interaction region, where the higest radiation doses occur. The ATLAS experiment will require a new particle tracking system for SLHC operation. In order to cope with the increase in background events by about one order of magnitude at the higher luminosity, an all silicon detector with enhanced radiation hardness is being designed. The new silicon strip detector will use significantly shorter strips than the current SemiConductor Tracker (SCT) in order to minimise the occupancy. As the increased luminosity will mean a corresponding increase in radiation dose, the classic concept of p-in-n silicon microstrip detectors as used in the current ATLAS SCT needs to be abandoned for the SLHC. These p-in-n detectors (p-strips processed into n-type silicon) are just sufficient for the radiation levels of the present LHC, and would be quickly rendered useless by the large SLHC radiation flux of up to 1016 neq /cm2. It is clear that a new generation of extremely radiation hard silicon detectors is required on the timescale of only a few years, much less than available for the SCT development. A massive R&D programme, involving many particles physics groups and several leadings manufacturers of silicon detectors for particle physics, is underway to develop silicon sensors with sufficient radiation hardness. In this framework new sensor materials like p-type silicon and the 3D technology are investigated. In parallel, the SCT commissioning experience has taught us to look into alternative module concepts, in which higher levels of integration are combined with the modularity of the SCT approach. At the same time, new front-end electronics and readout systems are being designed to cope with the higher data rates. We will reporto n the status of the R&D projects on radiation hard silicon strip detectors for particle physics, linked to the SLHC upgrade of the ATLAS microstrip detector. We will also present the most promising silicon detector and module concepts for the different radiation levels in the different regions of the ATLAS strip detector. The challenges of building, powering, cooling and Reading out a very large strip detector with several millions of detector channels within tight material, space and time constraints wil l also be discussed. Ideas on posible schemes for the layout and support mechanics will be shown.