Preparation of 231Pa targets

231Pa is an alpha-emitter belonging to the actinide group. Because it is both toxic and highly radioactive, it requires special precautions during target fabrication. The isotopic material was available in the chemical form of dried nitrate. It had to be converted to Pa-oxide, which is our most favourable source material for the preparation of actinide targets. Targets in the thickness range between 70 and 100 μg/cm2 were produced by cold crucible electron beam evaporation–condensation on different backings and target frames.