SUPERCONDUCTING CAVITIES FOR PARTICLE ACCELERATORS

Industrial production of about 150 superconducting cavities of 352 MHz frequency, which will allow upgrading the LEP energy from 55 to about 90 GeV per beam, is presently in progress. While cavities of this typ e are traditionally made of bulk niobium sheet, LEP cavities will be m ade of high purity copper internally sputter-coated with a thin layer of niobium (about 1 mum). The advantages of this approach are outlined and the history of its development at CERN briefly presented. The low -temperature physics aspects of this study are discussed on the ground of the available experimental data.