The Munich Accelerator for Fission Fragments - MAFF T. Faestermann ab * , W. Assmann ac , L. Beck a , H. Bongers ac , W. Carli a , M. Groß ac , R. Großmann ac , D. Habs ac , P. Hartung a , S. Heinz ac , P. J¨ uttner d , O. Kester ac , R. Kr¨ ucken ab , H.-J. Maier ac , P. Maier-Komor ab , F. Nebel ab , F. Ospald ac , M. Pasini ac , M. Schumann ac , J. Szerypo ac , P.G. Thirolf ac , F. Tralmer d and E. Zech ab a Maier-Leibnitz-Laboratory for Nuclear and Particle Physics, D85748 Garching, Germany b Physik Department E12, Technische Universit¨at M¨ unchen, D85748 Garching, Germany c Sektion Physik, Ludwig-Maximilians-Universit¨at M¨ unchen, D85748 Garching, Germany d Forschungsreaktor M¨ unchen II, D85748 Garching, Germany At the Munich research reactor FRM-II a radioactive beam facility is planned. About 10 14 fissions/s will be induced by thermal neutrons in a target of 235 U. Fission products will be ionised, extracted from the neighbourhood of the reactor core, mass analysed and cooled. For some nuclides more than 10 11 mass separated ions per second can be obtained. One ion species will be selected in a high-resolution separator and accelerated up to 5.9 MeV/u. 1. INTRODUCTION Proton-rich nuclei have been studied extensively up to and beyond the drip-line. Decay properties of practically all N=Z nuclei up to 100 Sn are known [1] and a substantial number of proton emitting nuclides has been observed [2] for odd-Z nuclei above Sn. Much more open territory lies on the neutron-rich side of the chart of nuclides, because most nuclear reactions produce radioactive nuclei that evaporate neutrons. Thus there is a strong need for neutron-rich radioactive ion beams. The best method to produce neutron-rich species is low energy fission of actinide nuclei, for which the most effective way is thermal neutron induced fission provided one has a source of thermal neutrons. In Garching near Munich construction of the high-flux reactor FRM-II has long been completed and now it obtained its final approval on May 12, 2003. At a moderate thermal power of 20 MW it will produce a maximum flux of 8 · 10 14 neutrons cm -2 s -1 , which will be used to induce fission in a 235 U target. The ionised fission products will be extracted and mass analysed and finally a radioactive nuclear beam of sufficient energy for nuclear reactions will be produced. Such a concept has already earlier been studied for the ILL reactor in Grenoble (PIAFE)[3]. * corresponding author, e-mail: thomas.faestermann@ph.tum.de Nuclear Physics A 746 (2004) 22c–26c 0375-9474/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysa.2004.09.106