SURFACE CLEANING EFFICIENCY MEASUREMENTS FOR UHV APPLICATIONS

Abstract High-energy particle accelerator UHV systems subjected to energetic charged particle or photon bombardment are particularly sensitive to surface contamination. Well-established cleaning procedures employing solvents such as Freon and perchloroethylene to prepare vacuum system components have been used at CERN for many years. The recently adopted legislation which prescribes or strongly limits the use of some chemicals has led CERN to undertake a qualification programme using electron stimulated desorption, Auger spectroscopy 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 components. Some solvents have been found to be as good, if not better, than Freon when detergents cannot be used.