Evolution of the R³B Setup

The R³B experimental setup was designed and developed on the basis of more than 20 years of experience with the LAND/ALADIN setup in Cave C at GSI. Compared to its predecessor, R³B is engineered to deliver significantly increased detection efficiency and resolution while providing high-rate capability and handling nuclei with higher magnetic rigidity.

Using the facilities in Cave C and secondary beams delivered by the FRS, individual components of the setup were rigorously tested. Cave C provided excellent conditions not only for validating subsystems, but also for performing successful physics experiments with the new setup during Phase-0 of FAIR.

Phase-0 Setup Configuration

The standard R3B setup operated in Cave C comprised several key detection layers (see figure below):

• Upstream of the target: Specialized detectors placed before the target for unique identification of incoming radioactive beams.
• Target Area: The target surrounded by the CALIFA detector alongside a prototype of the target-recoil detector.
• Forward Detection: The NeuLAND detector for precise neutron measurement, while heavy-ion fragments were tracked using fiber detectors and the time-of-flight wall TOFD.

Transition to HEC at FAIR

In 2026, the relocation to the High-Energy Cave (HEC) at FAIR commenced, marked by the transfer and installation of the large GLAD vacuum chamber as the first major component.