Abstract
The Pixel Detector is the innermost part of the CMS Tracker. It therefore has to prevail in the harshest environment in terms of particle fluence and radiation. There are several mechanisms that may decrease the efficiency of the detector. These are mainly caused by data acquisition (DAQ) problems and/or Single Event Upsets (SEU). Any remaining efficiency loss is referred to as the dynamic inefficiency. It is caused by various mechanisms inside the Readout Chip (ROC) and depends strongly on the data occupancy. In the 2012 data, at high values of instantaneous luminosity the inefficiency reached 2% (in the region closest to the interaction point) which is not negligible. In the 2015 run higher instantaneous luminosity is expected, which will result in lower efficiencies; therefore this effect needs to be understood and simulated. A data-driven method has been developed to simulate dynamic inefficiency, which has been shown to successfully simulate the effects.
Highlights
The Pixel Detector is the innermost part of the CMS Tracker
The simulation of the dynamic inefficiency based on double column loss can be verified by studying the track incidence angles
The incidence angles are defined in the local coordinate system, which can be seen in figure 4(a)
Summary
The Pixel Detector is the innermost part of the CMS Tracker. It has to prevail in the harshest environment in terms of particle fluence and radiation. We measure the performance of the detector in terms of hit efficiency [3], which is the probability to find a pixel cluster in any given sensor along a charged particle trajectory. A data-driven method has been developed, in which the hit efficiency is parametrised for each module as a function of instantaneous luminosity and module position (layer, ladder and ring coordinates). In all three layers of the barrel part of the detector, the dynamic inefficiency is simulated in this way.
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