One important upgrade for HL-LHC is the installation of new collimators, called TCLD, in the dispersion suppressors next to IR7 and IR2. The TCLDs are needed for proton and heavy-ion operation to intercept particles that differ from the main beam in either energy or, in the case of ions, charge-to-mass ratio. In IR7, the source of those losses is scattering in the primary collimator, where any out-scattered particles risk to escape the downstream collimators and instead impact the cold magnets in the dispersion suppressor. In IR2, the TCLDs should catch Pb ions that have picked up an extra electron in the collisions at the ALICE experiment, in order to avoid that they hit the cold aperture.

To make space for an IR7 TCLD, a standard LHC dipole will be replaced by two shorter and stronger 11 T dipoles, with the TCLD in between. In IR2, the TCLDs will instead be installed without 11T dipoles in the space of the empty connection cryostat. For each concerned IR, two TCLDs (one per side) are scheduled to be installed in LS2.

The TCLD consists of two high precision, movable tungsten jaws that embed precise beam-position monitors. A first prototype has been successfully completed in-house at CERN. The main production has been outsourced to industry, where four operational units and one spare are being built. The first industrially built TCLD collimator arrived at CERN in January 2019 for necessary tests and inspection by the CERN teams before installation in the LHC tunnel.

The TCLD collimators will be some of the first HL-LHC devices to be used with beam in the LHC at the start up after LS2. The delivery of the first TCLD marks an important milestone for the HL-LHC collimation upgrade that will make it possible to reach higher beam intensities and luminosities in the future.