Physics case
FAIR, the Facility for Antiproton and Ion Research, which is under construction at GSI in Darmstadt, will be the world’s foremost accelerator complex and experimental facility for nuclear physics. At its high-energy branch, reaction studies in inverse kinematics will be performed by the R3B collaboration using the full energy range available from the Super-FRS without further stopping, cooling or accumulation, that is 200–2000 MeV per nucleon.
The research program planned covers a wide variety of scattering experiments such as heavy-ion induced electromagnetic excitation, knockout and breakup reactions, light-ion induced elastic, inelastic and quasi-free scattering together with relativistic nucleus-nucleus collision experiments. The energy domain available to R3B is unique in the world for RIB reaction studies and has several experimental advantages. For example, in scattering experiments at these energies the nuclear transparency has a maximum which allows for maximally unbiased single-particle or cluster knockout reactions like quasi-free scattering, the reaction mechanism can be well disentangled from structuralfeatures and it is fully feasible to perform full ion-by-ion tracking to thus achieve the highest resolution.
Relativistic nucleus-nucleus collisions experiments at these energies will allow asymmetric nuclear matter to be explored up to 2-3 times normal nuclear matter density. The energy and the acceptance of the experiment correspond fully to the characteristics of the RIB production at FAIR, meaning that R3B will be the prime project to perform reaction studies of the isospin frontier opened up by the Super-FRS.