Why was the Large Hadron Collider closed? Answers to the main questions

The Large Hadron Collider (LHC) located near Geneva has stopped its work. It will undergo upgrades over four years to become a high-luminosity Collider. The world's largest particle accelerator will become much more efficient and provide scientists with vast amounts of information about elementary physics. How the TANK will change and what is the value of its work is in the Izvestia material.

Why did they close the hadron Collider?

• The European Organization for Nuclear Research (CERN) announced that the Large Hadron Collider stopped working on June 29. The scientists shut down the accelerator to begin the third long period of downtime, the so—called large-scale maintenance and modernization program that will transform the facility into a high-luminosity Collider. Retrofitting the LHC will be CERN's largest engineering project since the construction of the collider itself.

• The launch of the updated accelerator in test mode is planned for 2028, and full-fledged scientific work will begin on it in 2030. The total cost of the upgrade will be $1.5 billion. This amount will be covered by CERN membership fees, as well as in-kind contributions from non-member countries such as the United States, Japan, Canada and China. Such a contribution in the form of material resources, equipment, technologies or services will amount to 15% of the total cost.

• The main objective of the upgrade will be to increase the luminosity of the collider. This is a physical parameter that measures the number of particle collisions per unit time. The high-luminosity collider will collide 10 times more particles than was planned in the LHC's original design. More collisions will provide scientists with more data to study, and this will increase the likelihood of new discoveries in particle physics.

What will be the changes?

• The modernization of the LHC will consist in a complete replacement of components in a 1.2 km long section of the total 27-kilometer circular tunnel through which particles are dispersed. New superconducting magnets made of niobium-tin alloy will be installed to increase the number of collisions. They will create a stronger magnetic field than the old niobium-titanium alloy used in the tank.

• The high-luminosity collider will receive several new technologies developed specifically for it. For example, the so-called crab resonators. These are devices that tilt clumps of accelerated particles so that they meet each other directly, rather than at an angle, which will make experiments on them more effective. It is also planned to introduce crystal collimators that will remove random particles, and new high-temperature superconducting power transmission lines.

• Since the collider will transmit many times more data, it will also require updating its detectors, which collect information about acceleration and particle collisions. During the downtime, the main detectors of the ATLAS and CMS collider will be updated, each of which is the size of a multi-storey building. The detectors will be integrated with artificial intelligence to make it easier for scientists to use the data they receive.

• The LHC upgrade has already required the creation of a new engineering infrastructure. Construction work for this purpose began back in 2018 and lasted for four years. New shafts with a length of 80 m and a diameter of 10 m, underground spaces for equipment placement and 300-meter galleries for cable laying were dug for the ATLAS and SMS detectors, which record data on acceleration and particle collision.

What is the significance of the Large Hadron Collider?

The Large Hadron Collider was built in 2008 to study elementary particles. Its 27-kilometer underground tunnel is used to accelerate proton beams to speeds close to the speed of light using superconducting magnets cooled to almost absolute zero. Accelerated particles collide, which allows you to create new particles and study them at the deepest level. The data is collected using four detectors located along the tunnel.

• Already in 2012, the LHC fulfilled one of its main functions — with its help, the Higgs boson was discovered, a special particle that is responsible for the mass of other particles. It was hypothetically determined back in 1964, but experimentally its existence was confirmed only thanks to the work of the LHC. The discovery of the Higgs boson has completed the description of the so-called Standard Model, which describes the physics of elementary particles. In addition, the LHC has allowed us to make many more discoveries that are important for fundamental physics.

• The collider also has great practical benefits. The technologies developed for his work find further application in electronics, computing, computer science, and medicine. Discoveries in the field of superconductors, which allow stable transmission of electricity over long distances, are becoming especially valuable.

What discoveries will the new collider make?

• Over the entire period of operation, the LHC has produced about 55 million Higgs bosons. The updated High-luminosity Collider is expected to produce 380 million of the same particles within ten years. In turn, this will lead to even more collisions and provide scientists with more data for interpreting experiments, and more accurate than the LHC could provide in the old configuration. Based on these statistics, it will be possible to more accurately unravel the nature of some anomalies and deviations that the Standard Model cannot yet explain.

• The updated collider will also be expected to solve dark matter. A more frequent collision of protons could theoretically show scientists its particles. Until now, physicists have not been able to detect it, although its existence has been proven due to its gravitational influence. Given that about 27% of the universe consists of dark matter, its detection will be a breakthrough in physics.

• The conditions created by the collider during particle acceleration will also make it possible to test string theory in practice, which assumes the existence of additional dimensions beyond the four already known to mankind. Even if new measurements are not detected using a high-luminosity Collider, scientists may have a narrowed field for their search.