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

Multi-layer (235)UF4-(6)LiF-Au targets have been produced by vacuum deposition on thin polyimide foils with an areal density, measured by spectrophotometry, of about 33µgcm(-2). The foils were first covered with an Au-layer and then, with a second layer of (6)LiF, both by vapour deposition. The (235)UF4 layer was prepared by fluoride sublimation. Each deposited mass was characterized separately by means of differential weighing for the Au and (6)LiF layers and by low-geometry alpha-particle counting for the (235)UF4 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.