Huge cryogenic cold boxes lowered underground for LHC's major upgrade

CERN engineers have successfully installed two large cryogenic “cold boxes” deep underground near the ATLAS and CMS detectors as part of the High-Luminosity Large Hadron Collider (HiLumi LHC) upgrade. Manufactured by Linde in Germany, these cold boxes are essential components of the new refrigeration systems designed to cool the collider’s superconducting magnets to an ultra-low temperature of 1.9 kelvins (−271.3 °C), just a few degrees above absolute zero. This extreme cooling is necessary to enhance the magnets’ performance, thereby increasing the collider’s luminosity—the rate of particle collisions—which allows physicists to gather more data and explore fundamental particles with greater precision. The refrigeration system works by first precooling helium to 4.5 kelvins on the surface before it is further cooled underground to 1.9 kelvins through pressure reduction in the magnet cryostats, aided by four cold compressors integrated into the cold boxes. Installation of the cry