The particle accelerator that made it possible to discover the Higgs boson goes through the biggest renovation in its 10-year history. In June work began in Switzerland to upgrade the Large Hadron Collider, or LHC , to its future version, called the High Luminosity LHC, or HiLumi LHC. The objective is to prolong the useful life of the accelerator and to increase between five and seven times its luminosity, that is to say, the frequency of the collisions between protons, that up to now was of 1,000 million every second. With the improvement, researchers at the European Particle Physics Laboratory ( CERN ) will be able to observe very infrequent physical phenomena and fine-tune the accuracy of known results.
A technician tests new accelerator components. MAXIMILIEN BRICE CERN
The LHC produces, on average, one Higgs boson for every ten billion proton-proton collisions. This translates into a Higgs boson every ten seconds, more or less. Although it may seem fast, it was necessary to collect data for more than a year to confirm the discovery of that particle. The HiLumi LHC, which is expected to be ready by 2026, will generate data at an unprecedented speed, which will allow to investigate the properties of the Higgs boson and accelerate the discoveries in the coming decades.
In the 12 years after the renovation, the accelerator is expected to accumulate 10 times more data than in its first 12 years of operation. “It’s like being in a room, and instead of receiving the light from a 100-watt light bulb, a 1,000-watt light bulb suddenly comes on; everything looks much better, “says Lucio Rossi, the director of the HiLumi LHC project.
With the update, the experiments carried out by the laboratory to investigate physics beyond the standard model (the theory that describes the known elementary particles and their interactions) will benefit. One area of special interest at CERN is the study of supersymmetry, an unproven principle that suggests the existence of new heavy particles for each of the known elementary particles. If scientists prove their validity, this theory would justify the lightness of the Higgs boson mass, allow the unification of physical forces and even explain the nature of the particles that make up the mysterious dark matter. The particle collider is also used to check if quarks – which make up visible matter – can be made of something even more elementary.
Start of civil engineering works for HiLumi LHC. JULIEN MARIUS ORDAN CERN
To increase the brightness of the circular accelerator, CERN engineers will replace components in a 1,200 meter section of the device, which has a total circumference of 27 kilometers. In the LHC, two beams of protons circulate almost at the speed of light in opposite directions to be in one of the four collision points, where the particle detectors are installed (CMS, Alice, Atlas and LHCb). Among the new components, 24 superconducting quadrupole magnets are released that concentrate the proton beams in the interaction places to increase the collisions. In addition, for the first time the accelerator will include 16 radio frequency cavities, whose purpose is to tilt the beams just before the collision so that they collide head-on and not obliquely as they did so far.
In addition to the quadrupole magnets and the radiofrequency cavities, the technicians will also install four dipole superconducting magnets, which are responsible for curving the path of the beams. These devices are manufactured in CERN with the same technology as the new quadrupole magnets: an innovative niobium and tin alloy that is quite fragile but achieves a high uniform magnetic field, necessary to direct the enriched beams of protons.
The engineering work has started on the Swiss part of the complex, near the town of Meyrin, but the work will also continue for a time on the French side of the laboratory. In the first phase, ventilation and electrical equipment buildings will be built, as well as new underground galleries to house instruments far from the radiation emitted by the main ring. The particle accelerator will continue to work during assembly, except for two long technical stops scheduled, during which the usual maintenance tasks will be carried out and the new components will be installed for the high luminosity update.
