Limits on upgrade tracker layout from particle fluxes, signal-to-noise, and occupancy

We have investigated the layout for the inner tracking detector for ATLAS at the high luminosity upgrade of the LHC with respect to radiation damage and occupancy. Using simulated particle fluxes, we evaluate the signal-to-noise ratio based on measured radiation damage data, and estimate the expected occupancy. Tracking performance simulations yield alternative occupancy numbers and we find satisfactory agreement between the both. The dependence of occupancy and signal-to-noise on the location are used to evaluate the layout of the upgraded ATLAS inner detector.