Development and application of a modular test system for the HV-CMOS pixel sensor R&D of the ATLAS HL-LHC upgrade

BackgroundHigh-voltage CMOS is a promising technology for the pixel sensor of tracking detectors in the collider experiments. Extensive studies are being carried out by the ATLAS Collaboration to investigate the possibility of using the HV-CMOS technology in the HL-LHC upgrade of the ATLAS inner tracker detector.
PurposeThe CaRIBOu (Control and Readout Itk BOards) is a modular test system developed to test the HV-CMOS pixel sensor prototypes and demonstrators.
MethodsThis test system consists of pixel sensor specific front-end chip boards, a control and readout board (CaR board), a central interface board and the back-end DAQ system. Currently, two DAQ solutions are available for the CaRIBOu system, one is based on the FELIX (front-end link eXchange) readout system and the other is based on the Gigabit Ethernet link.
ResultsVarious testbeam experiments have been carried out with the CaRIBOu system since 2015 for the pixel sensors fabricated by the AMS HV-CMOS 180 nm and 350 nm technologies.
ConclusionThe test results show that this test system is very flexible and could be adapted to the test of different pixel sensors with minimum effort, and the performance meets the testbeam requirements.