Preliminary conclusions
SVT track finding efficiency is of the order of 95% and does not appear to worsen significantly in the presence of nominal background and background 10 times higher than nominal.
For noise & thresholds 30% higher than nominal, the efficiency drops by ~ 10%. The loss of efficiency is particularly significant for cosQ ~ 0 tracks.
The study of hit finding efficiencies shows that the effect is primarily due to the loss of Phi hits in the inner layers.