The impact of the ISR on accelerator physics and technology

The ISR (Intersecting Storage Rings) were two intersecting proton synchrotron rings each with a circumference of 942 m and eight-fold symmetry that were operational for 13 years from 1971 to 1984. The CERN PS injected 26 GeV/c proton beams into the two rings that could accelerate up to 31.4 GeV/c. The ISR worked for physics with beams of 30-40 A over 40-60 hours with luminosities in its superconducting low-{\beta} insertion of 1031-1032 cm-2 s-1. The ISR demonstrated the practicality of collider beam physics while catalysing a rapid advance in accelerator technologies and techniques.