Surface cleaning efficiency measurements for UHV applications

High-energy particle accelerator UHV systems subjected to energetic charged particle or photon bombardment are particularly sensitive to surface conta mination. Well-established cleaning procedures employing solvents such as F reon and perchloroethylene to prepare vacuum system components have been us ed at CERN for many years. The recently adopted legislation which prescribe s or strongly limits the use of some chemicals has led CERN to undertake a qualification programme using electron stimulated desorption, Auger spectro scopy and radioactive tracers to compare the cleaning efficiency of a wide range of alternative cleaning agents. It is found that detergents are preferable to solvents for cleaning UHV com ponents. Some solvents have been found to be as good, if not better, than F reon when detergents cannot be used. (C) 1999 Elsevier Science Ltd. All rig hts reserved.