Speaker
Description
The R3B (Reactions with Relativistic Radioactive Beams) experiment at GSI/FAIR is devoted to exploring the properties of nuclei located far from the valley of stability, with particular emphasis on their structure and reaction dynamics. To address these scientific objectives, a highly versatile reaction setup has been developed. This setup combines high detection efficiency, large geometrical acceptance, and excellent energy and momentum resolution, enabling kinematically complete measurements of a broad range of nuclear reactions induced by high-energy radioactive beams produced in inverse kinematics at relativistic velocities.
To support the design, operation, and analysis of the R3B setup, R3BRoot, a dedicated simulation and analysis framework based on ROOT, has been developed. R3BRoot builds upon the FairSoft and FairROOT frameworks, providing a unified platform for detector simulations that covers the full chain from event generation and digitization to reconstruction, as well as both online and offline analysis. Its modular structure is organized around tasks and parameter containers for calibration, mapping, and the storage of reconstruction variables, enabling users to configure detector responses, calibration constants, and analysis strategies in a flexible and reproducible manner.
A key feature of R3BRoot is the implementation of the Virtual Monte Carlo (VMC) interface, which allows the seamless use of different transport engines (e.g., GEANT3 and GEANT4) without requiring modifications to detector geometries or user code. This abstraction is particularly valuable for benchmarking simulations with different physics models and for ensuring long-term code sustainability. Furthermore, R3BRoot integrates ROOT I/O, visualization, histogramming, and online analysis tools, ensuring full compatibility with the workflows commonly employed in the nuclear and high-energy physics communities.
In this contribution, we present the design principles and current capabilities of R3BRoot, illustrate its use in detector development and data analysis, and discuss recent improvements and applications within the R3B Collaboration.
