RNB production with thermal neutrons Original Research Article

Thermal neutron induced nuclear fission is the most suitable method to produce neutron-rich isotopes (70⩽A⩽160) due to the large fission cross section and the high thermal neutron fluxes in modern reactors. Intensities of mass separated neutron rich nuclei of some 1011 ions/s are expected, e.g. for 91Kr, 132Sn or 144Cs from 235U diluted in a porous graphite target. Several front runners with low-energy fission-fragment beams exist like OSIRIS in Studsvik. In order to get beams of neutron-rich nuclei at the Coulomb barrier, the PIAFE project worked out a first concept of production and mass separation of high-intensity beams of fission fragments. At the new Munich high-flux reactor FRMII, the Munich Accelerator for Fission Fragments (MAFF) is under development to make use of post accelerated beams of neutron rich isotopes for experiments in many different fields of nuclear physics, solid state physics and medicine. One key experiment will be the production and the study of very heavy elements. An overview of the production method of neutron-rich isotopes by thermal neutron induced fission, and of the expected yields will be given and the development of target–ion-sources and of the fission targets for MAFF will be characterized.