The Munich accelerator for fission fragments (MAFF) at the new reactor FRM II

In Garching near Munich the new research reactor FRM II is under construction. It is supposed to be commissioned in 2001. The reactor will have a power of 20 MW, a rather small core diameter of 25 cm and a maximum neutron flux of 8 ·10¹⁴ n/cm²·s. Many new powerful instruments and novel experiments are planned in material science, solid state physics, nuclear physics, fundamental physics, chemistry, biology, medicine and technology. Consequently, the applications will range from material science diffractometers and inelastic neutron scattering over neutron tomography and cancer therapy to fusion producing the heaviest elements using accelerated fission fragments. The acceleration of radioactive isotope beams (RIB) is an important new field in nuclear physics and many new facilities are planned or under construction all over the world. Nuclear fission is the most suitable method to produce neutron-rich isotopes due to the large fission cross sections of thermal neutrons and the high thermal neutron flux in modern research reactors. Consequently, the new facility MAFF (Munich Accelerator for Fission Fragments) is foreseen for the new FRM II reactor. Beams of about 10¹¹ atoms/s are expected for ⁹¹Kr, ¹³²Sn, ¹⁴⁴Cs from a ²³⁵U source in a graphite cylinder close to the reactor core placed in a through-going beam-tube. Laser ionisation and a linear accelerator with IH and RFQ structures will provide the possibility to accelerate many different isotopes up to about 6 MeV/nucleon. Neutron-rich isotope beams are most interesting, because they will allow the investigation of several exciting new areas: i)Production of heavy and superheavy elements. ii) Atomic physics and chemistry of the heaviest elements. iii) Nuclear structure of astrophysically relevant nuclides and data for the r-process nucleosynthesis, iv) Isospin dependence of nuclear reactions. v) Application of radioactive isotope beams for solid state physics, medicine and radioactive waste management.