The Pixel Detector of the ATLAS experiment for the Run2 at the Large Hadron Collider

TL;DR

This paper describes the refurbishment and upgrade of the ATLAS pixel detector, including the installation of the Insertable B-Layer (IBL) with new technologies to enhance performance in high-radiation environments at the LHC.

Contribution

It presents the design, construction, and integration of the new IBL layer and upgraded pixel detector for improved performance in Run 2 of the LHC.

Findings

Successful installation of the IBL in 2014

Enhanced radiation hardness and pixel occupancy handling

Improved physics performance through reduced pixel size

Abstract

The Pixel Detector of the ATLAS experiment has shown excellent performance during the whole Run-1 of LHC. Taking advantage of the long shutdown, the detector was extracted from the experiment and brought to surface, to equip it with new service quarter panels, to repair the modules and to ease installation of the Insertable B-Layer (IBL). The IBL is a fourth layer of pixel detectors, and has been installed in May 2014 between the existing Pixel Detector and a new smaller radius beam-pipe at a radius of 3.3 cm. To cope with the high radiation and pixel occupancy due to the proximity to the interaction point, a new read-out chip and two different silicon sensor technologies (planar and 3D) have been developed. Furthermore, the physics performance will be improved through the reduction of pixel size while, targeting for a low material budget, a new mechanical support using light weight staves and CO2 based cooling system have been adopted. An overview of the refurbishing of the Pixel Detector and the IBL project as well as the experience in its construction will be presented, focusing on adopted technologies, module and stave production, qualification of assembly procedure, integration of staves around the beam pipe and commissioning of the detector.