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ATLAS Pixel Detector


Fig 1: 3D model of the ATLAS pixel detector.

The innermost tracking detector of ATLAS is a semiconductor pixel detector made of hybrid silicon pixel detector modules. Today the detector is made of two parts, the original ATLAS Pixel Detector which is running inside ATLAS from the beginning since 2008 and an additional innermost layer, the so called Insertable B-Layer (IBL) which have been added to the existing detector during the long shutdown (LS1) in 2014 following the Run 1 of LHC.


The original ATLAS Pixel Detector consists of three barrel layers around the beam axis and three disks in each direction along the beam axis, see Fig. 1. In the barrel region the Pixel Detector modules are arranged in so-called staves or ladders of 13 modules each. Every disk consists of 8 sectors with 6 modules each. In Fig. 2 you can see the outer barrel layer of the pixel detectors during the assembly fully equipped with 56 staves. Learn more about the original ATLAS Pixel Detector here.


Fig 2: Photo of an outer pixel barrel layer.


During the LS1 in 2013/14 after the Run 1 of LHC the IBL has been added to the pixel detector. The IBL is a fourth pixel barrel layer at R = 3.7 cm which is inserted between the old innermost pixel layer and a new smaller radii beam pipe, see Fig. 3.The IBL will preserve and increase the high tracking and vertex performance of the ATLAS Pixel Detector during the Run 2. It will take over from the old B-Layer the central role for the vertex finding and b-tagging in the high track density environment. The old B-Layer can't guarantee this role anymore due to the increased track density in Run 2 and the decreased performance because of radiation damage. Moreover a new luminosity detector called Diamond Beam Monitor (DBM) has been installed together with the IBL into the volume of the ATLAS Pixel Detector. The DBM uses similar hybrid pixel detector modules with diamond as sensor material. The modules are arranged as 8 small telescopes with 3 modules each pointing to the interaction point allowing for a bunch by bunch high accuracy luminosity measurement and beam spot monitoring. Read more about IBL and DBM...


Fig. 3: Insertion of the IBL to the ATLAS Detector in May 2014.


For the IBL and DBM development and production our main contributions were the chip development and its testing as well as the module production and testing. In total 50% of the roughly 750 built modules were assembled and tested in Bonn. Today we are involved in operational tasks of the ATLAS Pixel Detector. Read more...


Apart from that we are involved in planning of upgrades of the ATLAS  Pixel Detector for future LHC luminosity upgrades. For the HL-LHC phase starting around 2025 an entire new inner tracking system called ITk is developed which includes a complete re-design of the exiting pixel detector. Read more...

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