Crab Cavities for HL-LHC

Superconducting Radio Frequency (RF) crab cavities are essential components for the High-Luminosity Large Hadron Collider (HL-LHC) project. The crab cavities will help increase the luminosity reached by restoring head-collisions at the interaction points. Two types of cavities are required, the Double Quarter-Wave (DQW) and the Radio Frequency Dipole (RFD), designed to compensate vertical (CMS) and horizontal (ATLAS) crossing angles respectively. A first prototype cryomodule containing two DQW crab cavities was successfully assembled and tested in the Super Proton Synchrotron (SPS) in 2018, and for the first time validating the crabbing concept with high-energy proton beams. A second cryomodule with two RFD prototype crab cavities is in the final assembly stages for its installation and testing in 2023-24. While the prototyping phase of the project is being finalized, series production of cavities and auxiliary systems has started. The target is to complete the construction and installation of eight cryomodules in the LHC during the Long Shutdown 3. The crab cavity project is a worldwide endeavour: in addition to CERN deliverables, major contributions from industrial partners and international collaborations are expected throughout the project.