Modular Experiment Control System packages for the CBM experiment

The Compressed Baryonic Matter (CBM) is a fixed-target experiment which will explore the QCD phase diagram through heavy-ions collisions using the beams from the SIS100 accelerator at FAIR. Its physics program characteristics led to a choice for a self-triggered and free-streaming data acquisition, followed by an online full reconstruction and selection chain in software. Such a system can operate reliably and efficiently only with a performant Experiment Control System (ECS) to ensure the synchronization and data quality of all sub-systems. The development of a CBM-specific Python based solution, focused only on the Experiment Controls and on the upper layer of Detector Controls (state and configuration propagation), was chosen after looking at existing solutions. It is divided in three packages, from an experiment independent modular core to user interfaces, in order to allow maximal quality checks of the core functions. This article presents the design choices for this ECS, the technical core package, the CBM ECS implementation package and the demonstrator GUI package based on it. All three packages are now available in demonstrator versions, with test coverage and typing coverage both above 90% for the core package. They will be deployed for validation in the CBM demonstrator, mini-CBM (mCBM).