While the HL-LHC era for proton collisions starts in 2029 with the operational Run 4, the aim is to achieve the target HL heavy-ion performance already in Run 3 following the upgrade of the ALICE experiment during LS2. Thanks to the LHC injector upgrade program successfully completed during LS2, and in particular due to the planned deployment of slip stacking at the SPS, more than 20 MJ of stored Pb beam energy are targeted already in 2023. Achieving this goal is one key milestone for LHC operation this year.

Deploying these unprecedented ion beam parameters requires further improvements to the collimation cleaning performance, as confirmed in Run 2, where beam losses affected operation already at stored beam energies of about half the HL-LHC target. The collimation upgrade relies on the novel crystal collimation concept, where tiny, 4 mm long crystals bent to a curvature radius of 80 m, are used instead of the conventional primary collimation stage. These crystals bend halo particles by a design angle of 50 micro-rad and steer them coherently on secondary collimators that serve as channeled-halo absorbers. At the LHC, a total of four bent crystals are needed for horizontal and vertical collimation of both beams. During Run 2, a prototype crystal-collimation system was installed in the LHC IR7 with the aim to demonstrate the feasibility of this advanced collimation technique at LHC energies. This effort was initially part of the LHC Collimation Project with critical support from the UA9 collaboration. The scope of the HL-LHC upgrade involved the procurement of new bent crystals and the replacement of all the 4 prototype devices in IR7 with new crystal primary collimators (called TCPCs), optimized for performance and operational reliability.

Fulfilling this goal was a demanding endeavor. The TCPC construction was initially part of the Russian in-kind scope and had to be internalized following delays and the eventual cancellation of this collaboration. The installation of new devices was staged in two phases, with the vertical TCPCs installed during the YETS2021-22 and the horizontal ones during the YETS2022-23. The first installation was very successful, and the new devices could already be commissioned with beam in 2022 during a dedicated Pb ion beam test ahead of the upcoming physics 2023 run. The remaining two horizontal units were installed in February 2023. However, during commissioning of the hardware, a mechanical issue was revealed with the linear position stage of the B1 TCPC. This device was temporarily removed for repair. It will be installed back in IR7 during the first LHC technical stop at the end of June 2023, providing the fully upgraded crystal collimation system, well in time for the Pb ion run in October.