RF contacts for the LHC collimators

The radio frequency (RF) contacts for the secondary collimators of the LHC accelerator being built at CERN must satisfy several stringent requirements in terms of electrical contact resistance, mechanical robustness, wear resistance and high temperature stability. The guidelines leading to the final choice of contact materials will be discussed in detail, and the results of the experimental tests carried out in order to validate the choices will be illustrated, with particular emphasis on the measurements of contact resistance of various metal pairs.