On 27 January 1971, the first proton collisions inside the Intersecting Storage Rings at CERN heralded the beginning of a new era of experimental physics, one shaped by the ever-increasing energy reached by these discovery machines. On the occasion of this special anniversary, former LHC project director Lyn Evans and former ATLAS spokesperson Peter Jenni recount the history of hadron colliders in a CERN Courier feature article, from their conceptualisation by Norwegian engineer Rolf Widerøe in 1943 through to the quest for high luminosity and new energy frontiers opened up by the High-Luminosity LHC and future colliders.
From the Intersecting Storage Rings to the SPS proton–antiproton collider, the Tevatron (Fermilab) and finally the Large Hadron Collider, the road to higher energy hadron colliders was an arduous one, requiring the invention of countless concepts and technologies, not to mention sharp political skills. But the payoff was spectacular. The unprecedented energy available in hadron collisions and the versatility of the detectors complementing the machines led to many of the most famous particle-physics breakthroughs, including the discoveries of the W and Z bosons at the Super Proton Synchrotron, the top quark at the Tevatron and, of course, the Higgs boson at the LHC.
While the LHC has at least 15 years of operation ahead of it, a technical and financial feasibility study is under way to assess CERN’s next step into the unknown: a 100 km circular hadron collider with an energy of at least 100 TeV, as recommended by the recent update of the European Strategy for Particle Physics. If built, the success of such a machine will rest on the lessons learned from previous generations of hadron colliders and their fantastic detectors.