Special aspects on nuclear targets for high-energy heavy-ion accelerator experiments

Important facts about the GSI UNILAC accelerator are reviewed under the special aspects of target and stripper foil applications including general range considerations as seen after the upgrading of the machine to an energy of 20 MeV/u for all ions up to uranium. It is also reported about current works and recent developments in target preparations at GSI divided into four main groups of preparation procedures with sufficient overlap: cold rollings, carbon sublimation-condensations, focussed heavy-ion sputter deposition, and the wide field of high-vacuum evaporation-condensations. Among others, a Ca reduction-distillation procedure is described, a new assembly is shown for sublimation-condensations of uniform C layers of 0.1 to 0.76 mg/cm2 area densities. A selection of only a few applications of targets at the UNILAC can be given. Improved actinide targets are discussed, in-beam measurements of properties of targets on rotating wheels are explained, and a large-area target wheel with a circumference of nearly one meter is shown. SEM micrographs of damaged targets are given and explained. (orig.)