Simulation of the Dynamic Inefficiency of the CMS Pixel Detector

TL;DR

This paper presents a data-driven simulation method for dynamic inefficiency in the CMS Pixel Detector, caused by high luminosity conditions affecting efficiency, with implications for future high-luminosity runs.

Contribution

The paper introduces a novel data-driven simulation approach to model dynamic inefficiency in the CMS Pixel Detector under high luminosity conditions.

Findings

Successfully simulates dynamic inefficiency effects

Quantifies inefficiency at 2% during 2012 data

Prepares for efficiency challenges in future runs

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.