How low-cost devices can help on the way to ALICE upgrade

Abstract

Cheap, ready to install and simple to configure, minicomputer and microcontroller boards have been in use in ALICE for a few years for specific, non-critical tasks, like integrating the environment sensors network in the experimental site, and to monitor and analyse clock signals. These systems have also been installed inside the ALICE experiment, in the presence of magnetic field and radiation, and subjected to a functionality test. While the major part of these devices proved to work correctly even under the experiment conditions, finally some weaknesses were revealed, thus excluding this class of devices from usage in the production setup. They have also played a role in the realization of scaled systems for the ALICE upgrade. With them, we have been able to simulate the presence of Front-End cards which are not yet available, allowing to proceed in the development of the software framework, of libraries and interfaces, in parallel with the production and validation of the hardware components. Being off-the-shelf and available everywhere in the world, they can be installed in remote institutes and laboratories participating to the collaboration. Some of the systems have been realised by students and trainees hosted at CERN for short periods of time. As well as being cheap and easy to procure, they proved to be a great didactic tool, allowing young collaborators to realise a complete system from scratch, integrate into a complex infrastructure and get a hands-on approach to modern control systems.The ambitious upgrade plan of the ALICE experiment expects a complete redesign of its data flow after the LHC shutdown scheduled for 2019, for which new electronics modules are being developed in the collaborating institutes. Access to prototypes is at present very limited and full scale prototypes are expected only close to the installation date. To overcome the lack of realistic HW, the ALICE DCS team built small-scale prototypes based on low-cost commercial components (Arduino, Raspberry PI), equipped with environmental sensors, and installed in the experiment areas around and inside the ALICE detector. Communication and control software was developed, based on the architecture proposed for the future detectors, including CERN JCOP FW and ETM WINCC OA. Data provided by the prototypes has been recorded for several months, in presence of beam and magnetic field. The challenge of the harsh environment revealed some insurmountable weaknesses, thus excluding this class of devices from usage in a production setup. They did prove, however, to be robust enough for test purposes, and are still a realistic test-bed for developers while the production of final electronics is continuing