Chapter 1: High-Luminosity Large Hadron Collider

The Large Hadron Collider (LHC) was successfully commissioned in 2010 for proton–proton collisions with a 7 TeV centre-of-mass (c.o.m.) energy. It delivered 8 TeV c.o.m. proton collisions from April 2012 until the end of Run 1 in 2013. Following the Long Shutdown 1 (LS1) in 2013–2014, it operated with 13 TeV c.o.m. proton collisions during Run 2 from 2015 until the end of 2018, reaching a peak luminosity twice the nominal design value. At present (2020), the LHC is in Long Shutdown 2 (LS2) during which further consolidation measures (insulation and retrofitting of the protection diode connections) are being pursued; these should enable the LHC to reach its nominal design beam energy of 7 TeV. As a consequence of the coronavirus pandemic, LS2 will last almost one year longer than foreseen, with Run 3 now planned to start at the beginning of 2022.