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.
Highlights
In order to make them more accessible for the potential repairs, the Pixel Detector was extracted from the ATLAS detector in April 2013 to replace SQPs by New Service Quarter Panels during LS1
During LS1, the detector was extracted from the experiment and brought to the surface to equip it with New Service Quarter Panels (nSQP) and repair the disabled modules
The disabled modules were reduced from 5% to 1.9% after the re-installation of the Pixel Detector
Summary
In the Pixel Detector, the opto-boards are used for the electric-optic conversion of the signals from the modules. In Run-1, the opto-boards were housed on the SQPs which were installed with the detector and carry electrical power, cooling and optical data both into and out of the detector. With the nSQP, the electric lines can be extended to the outside of the detector, and it realizes the easier access to the opto-boards. There were several sources of problems like broken front-end chips and disconnection of the electrical lines in SQP. They were fixed as much as possible during replacement of the SQPs. The Pixel Detector was re-installed into the ATLAS detector in December 2013. The disabled modules were reduced to 1.9% after the re-installation [3]
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