PREPARATION OF HOMOGENEOUS ISOTOPIC TARGETS WITH A ROTATING SUBSTRATE

Isotopically enriched accelerator targets were prepared using the evaporation-condensation method from a resistance heating crucible. For high collection efficiency and good homogeneity the substrate was rotated at a vertical distance of 1.3 to 2.5 cm from the evaporation source. Measured collection efficiencies were 13 to 51 mug cm-2 mg-1 and homogeneity tests showed values close to the theoretically calculated ones for a point source. Targets, selfsupporting or on backings, could be fabricated with this method for elements and some compounds with evaporation temperatures up to 2300 K.