Basic research at GSI for the transmutation of nuclear waste

In the course of the concerted action “Lead for ADT”, which preceded the HINDAS project [1], an innovative experimental method has been developed at GSI-Darmstadt. This new approach is based on the inverse-kinematics method where a liquid-hydrogen target is bombarded with heavy projectiles. The reaction products are identified in-flight in mass and atomic number in a high-resolution spectrometer. Using this technique, we could detect, identify unambiguously and analyse about thousand nuclides per system before radioactive disintegration with an accuracy in the order of 10% to 15% in most cases. Moreover, thanks to the high-precision measurements of the velocity of the final residues, we could determine by which mechanism (spallation-fission or spallation-evaporation) they were produced. The investigated systems provide stringent constraints to nuclear-reaction codes, in particular to the energy deposition in spallation, the modelling of the fission competition and the nuclide production in fission and on the energy dependence of spallation reactions. The new data will help to develop improved models with better predictive power for spallation reactions involving nuclei spanning a wide mass range.