Operation and performance of the ATLAS semiconductor tracker in LHC Run 2

The semiconductor tracker (SCT) is one of the tracking systems for charged particles in the ATLAS detector. It consists of 4088 silicon strip sensor modules. During Run 2 (2015–2018) the Large Hadron Collider delivered an integrated luminosity of 156 fb-1 to the ATLAS experiment at a centre-of-mass proton-proton collision energy of 13 TeV. The instantaneous luminosity and pile-up conditions were far in excess of those assumed in the original design of the SCT detector. Due to improvements to the data acquisition system, the SCT operated stably throughout Run 2. It was available for 99.9% of the integrated luminosity and achieved a data-quality efficiency of 99.85%. Detailed studies have been made of the leakage current in SCT modules and the evolution of the full depletion voltage, which are used to study the impact of radiation damage to the modules

Judgment Estimates of the Moments of Pert Type Distributions

This paper considers the problem of estimating the moments of a statistical distribution from judgment estimates of various percentiles of the distribution and its mode. The results of this study indicate that 5 and 95 percentiles are superior to the 0 and 100 percentiles used in classical PERT; they lead to estimates that are robust to variations in the shape of the distribution, and also there is some experimental evidence which indicates that they can be estimated more accurately from one's "experience." It was also found experimentally that the single time estimate used in CPM gave a slightly biased estimate of the mean, whereas the three time estimates used in PERT gave unbiased estimates of the mean.