A cryogenic target for direct reaction studies with exotic beams

A cryogenic system has been designed to make a thin target of solid hydrogen isotopes usable under vacuum, with a particle beam. In order to insure the homogeneity of the target, an equivalent pressure is maintained with helium on both sides of the target windows during the formation of the solid hydrogen. The system developed is described and the results obtained with 1 mm thick solid hydrogen and deuterium targets, in two different experiments using the radioactive beams from the SPIRAL facility, are presented. The flatness achieved was better than a few percent in both experiments.