ATLAS ITk

Upgrade of the ATLAS Pixel Detector

The pixel detector is the innermost detector (as part of the Inner Tracker) in the ATLAS Detector located at CERN, Geneva. As the LHC will soon receive a luminosity upgrade, called HL-LHC, several ATLAS detector parts have to be replaced during the LHC Phase II upgrade to handle the increased luminosity of up to 7.5 x 10³⁴ cm^-2s^-1.

The new pixel detector of the new ATLAS Inner Tracker (ITk, Fig. 1) will consist of five barrel layers and a few end-cap disks equipped with around 10,000 pixel modules covering a total area of about 14 m². Four readout chips with approx. 600,000 pixels each will be mounted on every module to measure and reconstruct the trajectories of charged particles produced in collisions.

Compared to the currently installed ATLAS Inner Detector, the amount of pixel modules of the ATLAS ITk will be increased by a factor of around five, the active area will be about eight times larger, and the total amount pixels will increase from approx. 92 million to 5 billion pixels. This will lead to significant improvements in detection and reconstruction of particle tracks and will ensure that the ATLAS ITk will be able to withstand the high-radiation environment of the HL-LHC.

During the design phase of the ATLAS ITk pixel modules, our group participated in designing the flexible PCB (flex) for the prototype hybrid modules equipped with FE-I4B chips. Details about Siegen's flex development activities can be found here.

We recently entered the module production phase. We aim to assemble and test around 200 pixel modules. Furthermore, we will perform quality control tests of all 2000 flexes needed by the German cluster (consisting of Bonn, Göttingen, and Siegen) to build 2000 modules in Germany. More information about Siegen's recent assembly, module and flex testing activities can be found here.