Protection and monitoring of the ISR superconducting low- β quadrupoles

The eight superconducting magnets of the high-luminosity insertion, installed in the CERN Intersecting Storage Rings during autumn 1980, were designed intrinsically safe against quenches. Nevertheless, in order to prevent any damage to the windings or to the cryostats, an active interlock system will trip the power supplies in the case of quenches, overheating of current leads or abnormal liquid helium level. In addition, fast quench detectors will damp the ISR beam to prevent uncontrolled losses of protons.