Target conception for the Munich fission fragment accelerator

For the new high-flux reactor FRM II, the fission fragment accelerator MAFF is under design. MAFF will supply intense mass-separated radioactive ion b eams of very neutron-rich nuclei with energies around the Coulomb barrier. A central part of this accelerator is the ion source with the fission targe t, which is operated at a neutron flux of 1.5 x 10(14) cm(-2)s(-1) The targ et consists of typically 1 g of U-235 dispersed in a cylindrical graphite m atrix, which is encapsulated in a Re container. To enable diffusion and ext raction of the fission products, the target has to be maintained at a tempe rature of up to 2400 degrees C during operation. It has to stand this tempe rature for at least one reactor cycle of 1250 h. Comprehensive tests are re quired to study the long-term behaviour of the involved materials at these conditions prior to operation in the reactor. The present paper gives detai ls of the target conception and the projected tests. (C) 1999 Elsevier Scie nce B.V. All rights reserved.