Quantitative molecular plating of large-area ²⁴²Pu targets with improved layer properties

For measurements of the neutron-induced fission cross section of ²⁴²Pu, large-area (42cm²) ²⁴²Pu targets were prepared on Ti-coated Si wafers by means of constant current density molecular plating. Radiochemical separations were performed prior to the platings. Quantitative deposition yields (>95%) were determined for all targets by means of alpha-particle spectroscopy. Layer densities in the range of 100-150μg/cm² were obtained. The homogeneity of the targets was studied by radiographic imaging. A comparative study between the quality of the layers produced on the Ti-coated Si wafers and the quality of layers grown on normal Ti foils was carried out by applying scanning electron microscopy and energy dispersive X-ray spectroscopy. Ti-coated Si wafers resulted clearly superior to Ti foils in the production of homogeneous ²⁴²Pu layers with minimum defectivity.