Even as the US high-energy physics community is working to keep a world-class program for the next 10 years (see story on page 18), its counterparts in Europe and China are revving up discussions for longer-term projects—circular colliders 50 to 100 km in circumference that might be built in the coming decades.
The Institute of High Energy Physics (IHEP) in Beijing and CERN near Geneva have similar visions: Each might start with an electron–positron machine—perhaps 240 GeV in China and higher in Europe—and then convert to a proton–proton facility with center-of-mass collisions up to 100 TeV, about seven times as high as planned for the next stages of the Large Hadron Collider (LHC).
The China high-energy physics community, says IHEP director Yifang Wang, is looking for a successor to the 240-m Beijing Electron Positron Collider. For now, he says, “we are focusing on a 50-km ring as the lower...
