Source Preparation Clause Samples

Source Preparation. One aim of this project was to improve existing source preparation techniques. The source preparation is essential for high-precision beta spectra based on MMC detectors. The radioactive material must be completely embedded into the absorber material to ensure that every beta decay is detected and – in the ideal case – the decay energy is completely deposited into the absorber and entirely thermalized, i. e. transformed to heat. It has been known, e. g., that the presence of large (of order micrometers) salt crystals, that can form upon radionuclide deposition from a charged salt solution, can result in spectrum distortions. The reason is that a fraction of the decay energy deposited in the salt crystals is expended in the formation of crystal defects or long-lived electron-hole pairs and therefore not thermalized. For the absorber/source preparation within this project, the radioactive material was embedded into the absorber by two different methods. Using the first method, the radionuclide is firstly directly deposited onto one half of the absorber. Subsequently, the second half of the absorber is welded onto the first part to form a 4 geometry. For the second method, the radioactive material was deposited onto a separate thin noble metal foil that acts as a source carrier foil; this foil was subsequently placed between two half-absorber foils, and this foil stack was diffusion-welded together. The parameters of the diffusion welding processes depended strongly on the embedded source material and the absorber material. Several tests have been carried out to achieve suitable parameters. It is advisable to perform quality control checks of the embedded sources. There are several methods to deposit a radionuclide onto metal foils. Ion implantation [4] has the potential to provide ideal sources with the radionuclide implanted directly into the absorber material, but it is a complex and costly technique which requires dedicated facilities. Here, electrodeposition [1] as well as drop deposition were investigated. 6.1 Electrodeposition 6.2 Drop deposition and dispersion of the activity in the absorber material Micro dispensing system