CERN has started the cryogenic cooldown to 1.9 K (-271.3 °C, approx. -456.3 °F) of its 95-metre-long (approx. 312-ft-long) Inner Triplet String (IT String) test stand, a full-scale replica of equipment planned for the High-Luminosity Large Hadron Collider (HiLumi LHC) upgrade. The test stand is intended to validate the inner triplet beam-focusing magnet system and its supporting infrastructure ahead of an LHC upgrade that is set to enter operation in 2030.
CERN said this summer will mark the start of a four-year work period (Long Shutdown 3 – LS3) to transform the LHC into the HiLumi LHC. The project aims to increase by a factor of ten the number of particle collisions (“luminosity”), increasing the volume of physics data available for researchers.
The HiLumi LHC includes technologies that CERN said have never been used in a proton accelerator before, including superconducting crab cavities, crystal collimators and high-temperature superconducting electrical transfer lines to power the HiLumi magnets. The inner triplet magnets use a superconducting compound based on niobium and tin (Nb3Sn), which CERN said enables magnetic fields higher than those achieved with the current LHC niobium–titanium (NbTi) magnets, and they are planned to operate at 1.9 K (-271.3 °C), like the LHC magnets.
CERN built the IT String in an above-ground test hall to mirror the underground configuration, aiming to verify integration and collective performance under operational conditions. CERN said the cooldown is achieved using a liquid-helium refrigeration and distribution system and is expected to take several weeks to complete.
“All the systems have already been tested individually. The goal of the IT String is to validate their integration and their collective performance under operational conditions,” said Oliver Brüning, CERN Director for Accelerators and Technology. “The connection and operation of all the equipment in the IT String give us a chance to optimise our procedures before the actual installation in the tunnel, so that we will be prepared and ready for an efficient and smooth installation.”
