Forward pixel detector

The Edinburgh group is part of the UK collaboration which designs and develops the Forward Pixel Detector, a silicon pixel detector to provide precision measurements of charged particle tracks in the forward direction of the ATLAS experiment. The Forward Pixel Detector extends to both sides of the Barrel Pixel Detector, together forming the inner most detector layer of the experiment. They have a common diameter of ~70cm and a combined length of ~7m. In total they provide at least 100 million readout pixels of size 50x250 micromenters, to cope with the large particle multiplicities in the high luminosity run of the Large Hadron Collider. They are planned to be installed during 2022/23 as part of the new Inner Tracker (ITk) in the Phase II Upgrade of the ATLAS experiment.

The Edinburgh group leads the integration of the services of the Forward Pixel Detector, that is all links between the readout modules and a common interface of all pixel and strip tracking detectors, called Patch Panel 1 (PP1). This comprises the high-speed data links, the slow control, interlock and power lines as well as the cooling pipes, at least as far as the electrical grounding scheme is concerned. As a consequence we are involved in the design and layout effort for the Inner Tracker, negotiating and optimising the boundaries and interfaces between the pixel and strip tracking detectors. We contribute to the development of the pixel modules, the basic detector units, comprising silicon pixel sensors and readout ASICs as main elements. And we are part of the team developing prototype half-rings, equipped with modules and services, to test and demonstrate the detector design.

At Edinburgh we contribute a number of technologies and services to the collaborative effort of the project:

  • we test FE-I4 readout ASICs on wafer level, to qualify which chips can be used for module assembly after dicing
  • we design and test cresent flex tapes as custom made prototypes to distribute high voltage, low voltage, power and slow control signals as well as to read out data on the half-rings
  • we test commerial and custom solutions for electrical high-speed data links (optical links would break due to radiation levels)
  • we design automated quality control systems for testing flex-tapes and pixel modules from production

  • we develop precision silicon placement for module assembly
  • we provide PCB design for test boards

These activities are led by Dr Stephan Eisenhardt. Active group members are: Francisca GarayDr Corrinne MillsDr Georgios Sidiropoulos and Jon Webster. Earlier contributions came from: Dr Andreas Korn (now UCL), Paul Glaysher and Manuel Prossil.