Methods to Reduce Contamination in Targets Prepared by Vacuum Deposition
For some time, both the experimenters and we target makers have been concerned about the source of impurities which were found from experimental data obtained using targets prepared by vacuum vapor deposition. These impurities may arise from the process of producing the target, the separated isotope used in the evaporation, or contaminants introduced during the experiment. Some impurities such as carbon, oxygen and nitrogen are likely to be introduced into the target during evaporation, as a result of residual gases and contaminants, such as diffusion pump oil, present in the vacuum system. The present study was initiated to determine the source of impurities found in our targets. We would like to mention some of the experimenters who were kind enough to cooperate with us by bringing to our attention these impurities whenever they found them and, in addition, letting us use some of their data: D. F. Geesaman, W. Henning, M. S. Kaminsky, D. G. Kovar, W. Kutschera, G. C. Morrison, M. Paul, and S. J. Sanders.
KeywordsDiffusion Pump Evaporation Time Oxygen Contamination Aluminum Target Magnesium Isotope
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