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Description
The upgrade of the CMS pixel system will be presented, including its main goals, features and innovations, as well as the expected final performance. This upgrade project is part of a broad upgrade programme of CMS, motivated by a goal for CMS to achieve its full Physics potential, exploiting all the anticipated increases of the LHC performance.
The present pixel detector has worked very well since installation in 2008. It was designed to be efficient up to an LHC luminosity of 10^34Hz/cm2 and latest projections for LHC machine performance show that the bulk of the integrated luminosity coming in the next decade will be delivered with peak luminosities well in excess of 10^34Hz/cm2. The upgraded pixel detector is therefore required to maintain, if not improve upon the present excellent levels of performance, whilst withstanding the much harsher operating conditions we expect in future.
The pixel upgrade project is made possible by innovative developments in electronics, mechanics, cooling, readout and powering, all of which will be outlined. The upgrade will also profit from the installation of a new central beam pipe in CMS during the coming long-shutdown (LS1).
The combination of reduced dead-time, additional tracking layers and their optimized positioning, as well as a large reduction of mass inside the tracking volume, leads to great improvements in performance over the present system at all luminosities.
Radiation damage will limit the lifetime of the system. The present sensors are specified to withstand a fluence of 6x1014neq/cm2. We expect to be able to increase this rating by eventually employing new sensors with greater radiation resistance. Partial replacement of the upgraded detector is foreseen in the mechanical design, allowing substitution of degraded modules and allowing us to exercise our possible future options to install more advanced modules when these parts become available.
Organised by
Ferdinand Hahn PH/DT