Multi-layer 235UF4–6LiF–Au targets for high-resolution fission fragment measurements

• Multi-layer 235UF4–6LiF–Au targets were produced on thin polyimide foils.
• Prepared for future high-resolution measurements of fission-fragment properties.
• Different layers were prepared by physical vapour deposition.
• The foil and each layer were characterized separately for their areal density.

Multi-layer 235UF4–6LiF–Au targets have been produced by vacuum deposition on thin polyimide foils with an areal density, measured by spectrophotometry, of about 33 µg cm−2. The foils were first covered with an Au-layer and then, with a second layer of 6LiF, both by vapour deposition. The 235UF4 layer was prepared by fluoride sublimation. Each deposited mass was characterized separately by means of differential weighing for the Au and 6LiF layers and by low-geometry alpha-particle counting for the 235UF4 layer. The atomic abundances of the uranium base material have been measured by thermal ionization mass spectrometry. The targets were prepared for measuring fission-fragment emission yields with high mass-resolution.