CERN Courier Sep/Oct 2019
Welcome to the digital edition of the September/October 2019 issue of CERN Courier.
During the final decade of the 20th century, the Large Electron Positron collider (LEP) took a scalpel to the subatomic world. Its four experiments – ALEPH, DELPHI, L3 and OPAL – turned high-energy particle physics into a precision science, firmly establishing the existence of electroweak radiative corrections and constraining key Standard Model parameters. One of LEP’s most important legacies is more mundane: the 26.7 km-circumference tunnel that it bequeathed to the LHC. Today at CERN, 30 years after LEP’s first results, heavy machinery is once again carving out rock in the name of fundamental research. This month’s cover image captures major civil-engineering works that have been taking place at points 1 and 5 (ATLAS and CMS) of the LHC for the past year to create the additional tunnels, shafts and service halls required for the high-luminosity LHC. Particle physics doesn’t need new tunnels very often, and proposals for a 100 km circular collider to follow the LHC have attracted the interest of civil engineers around the world. The geological, environmental and civil-engineering studies undertaken during the past five years as part of CERN’s Future Circular Collider study, in addition to similar studies for a possible Compact Linear Collider up to 50 km long, demonstrate the state of the art in tunnel design and construction methods.
Also in this issue: a record field for an advanced niobium-tin accelerator dipole magnet; tensions in the Hubble constant; reports on EPS-HEP and other conferences; the ProtonMail success story; strengthening theoretical physics in southeastern Europe; and much more.