Until 1968, the AGS was the highest energy accelerator in the world, slightly higher than its 28 GeV sister machine, the Proton Synchrotron at CERN, the European laboratory for high-energy physics. While 21st century accelerators can reach energies in the trillion electron volt region, the AGS earned researchers three Nobel Prizes and today serves as the injector for Brookhaven's Relativistic Heavy Ion Collider ; it remains the world's highest intensity high-energy proton accelerator.