OPTIMAL REMOVAL OF SCATTERED PARTICLES AT MEDIUM ENERGY-STORAGE RINGS WITH INTERNAL TARGET

We have studied at which places projectiles that have been scattered by an internal target out of the acceptance of a medium energy storage ring, can be dumped locally so that the effort for shielding can be minimized. General arguments are given where slits should be installed and their effect on the useful ring acceptance is discussed. In addition we have carried out Monte Carlo simulations for the dispersion-free mode of operation of COSY, which show that approximately 86% of the lost beam can be removed locally with the use of only two sets of slits.