CERN Upgrade Plans for the LHC and its Injectors

The primary goal of CERN and the Large Hadron Collider (LHC) community is to ensure that LHC is operated efficiently, that it achieves nominal performance in the shortest term, and that its performance steadily improves. Since several years the community has been discussing the directions for maximizing the physics reach of the LHC by upgrading the experiments, in particular ATLAS and CMS, the LHC machine and the CERN proton injectors, in a phased approach. The first phase comprises construction of a new proton linac, LINAC4 and an LHC interaction-region (IR) upgrade, with the goal of increasing the LHC luminosity to 2−3×1034 cm−2s−1, while maximizing the use of mature magnet technologies and of the existing infrastructure. These two projects were approved by the CERN Council in December 2007 and are scheduled for completion in 2014. The second phase foresees further substantial improvements in the injector chain, with a proposed replacement of the aging PS and its booster, by a superconducting proton linac (SPL) and a new higher-energy storage ring, PS2, complemented by modifications in the existing SPS, together with major upgrades of the ATLAS and CMS detectors, and, possibly, including another upgrade of the interaction regions based on a different magnet technology, as well as complementary measures such as crab cavities, or a new beam structure. Completion of this second phase around 2018-2020 should allow further increasing the luminosity of the LHC towards 1035 cm−2s−1. On an even longer time scale, the magnet technology developed for the second phase could provide the route towards an ultimate energy upgrade of the LHC. In this report, I first recall a few key challenges inherent in the LHC baseline design, and then describe phased upgrade scenarios for the LHC and its injectors which overcome the design limitations and may ultimately lead to a 10-fold luminosity increase.