Control and Monitoring for a serially powered pixel demonstrator for the ATLAS Phase II upgrade

The Inner Tracker (ITk) is a new all silicon detector under development for the ATLAS Phase-II upgrade and will operate at the High Luminosity LHC. A serial power scheme will be used for the pixel detector. New elements are required to operate and monitor a serially powered detector, including a Detector Control System (DCS), constant current sources and front-end electronics with shunt regulators. A demonstrator for the three outer barrel layers of the pixel detector is built at CERN to verify and qualify the concept and to gain experience operating a serial power (SP) chain. It includes all required elements for controlling and operating SP chains safely, from an in- terlock system to in-situ monitoring with the new DCS. A first full electrical prototype with seven quad modules was successfully tested. This prototype includes pixel modules, the DCS elements, realistic services and can be read out by different data acquisition systems. Problems seen during the commissioning and operation of the small electrical prototype went into the requirements for the front-end (FE) chips. Many institutes worked on the development and integration of the in- dividual parts. Further and longer chains are under construction and will allow tests of multiple SP chains mounted on the same local support in parallel. It is also foreseen to operate a SP chain with 16 modules.