Comparative study of the direct and converter methods for high fission yields

The aim of the considerations below is to estimate the orders of magnitude for the production of radioactive nuclear beams (RNBs) at GANIL with possible evolutions of the present accelerator complex within the next decade. This study was requested by the Conseil Scientific du GANIL. In this respect, the time scale considered is intermediate between long range plans such as Eurisol, a R and D programme that is just starting in a European collaboration, and the present SPIRAL facility, which should enter into operation at the end of 2000. In this context we consider and compare methods to produce ISOL beams by fission and/or low energy spallation with the main goal of reaching 1014 fissions/s in the RNB production target. Such RNBs would complement the present SPIRAL beams obtained by fragmentation of the projectile or the target, that are limited to light elements if high intensities are required. The coupled LAHET + MCNP + CINDER code system is used for simulations. (authors)