The world’s largest particle accelerator returns to work after a long technical hiatus

In a statement, the European Particle Physics Laboratory (CERN) said the machine resumed work at 11:16 a.m. Lisbon time when two proton beams circulated in opposite directions at 450 billion electron volts (450 gigaelectronvolts).

However, it will take a few more months for the Large Hadron Collider (LHC), a 27-kilometre circular tunnel, to generate “high-density, high-energy” collisions of subatomic particles.

According to CERN, new data collection, for another four years, is expected to begin in the summer.

Before that, experts will gradually fine-tune the machine and safely increase the energy and density of the beams so that collisions can be initiated with a record energy of 13.6 billion electronvolts (13.6 electronvolts).

For CERN’s Head of Beam Department, Rodry Jones, quoted in the statement, the two proton beams, “which circulated at injection energy and contained a relatively small number of protons,” represented “the successful restart of the accelerator after all the hard work done over a period of time.” Long rest.

LHC closed in December 2018 and the new technical terminal, the second longest running of the improvement work, is expected to run until spring 2021, a deadline that ended up slipping.

“Equipment and infrastructure underwent major upgrades during the second long outage of the CERN accelerator complex,” said Mike Lamont, director of accelerators and technology at CERN, adding that the LHC “will now operate at higher power and thanks to major improvements to the injector. It will provide more data for experiments, which have been improved upon.” also “.

With the improvements made, physicists hope to deepen knowledge of the properties of the Higgs boson, an elementary particle discovered in 2012 in accelerator experiments, and to test more rigorously the Standard Model of particle physics and its various possible variants. Accessories.

Collisions involving oxygen ions will also be made at the Large Hadron Collider, which will improve our understanding of cosmic rays (active particles that interact with Earth’s atmosphere) and plasma of quarks and gluons, a state of matter that existed shortly after the Big Bang, the theory under which the universe was born 13.8 billion years ago.

It is expected that from 2026 onwards, the accelerator will start producing more collisions and more data, in higher brightness mode.

At the Large Hadron Collider, collisions of protons (hadrons) and heavy ions are generated at high energies to better understand the formation of the universe. The protons in the accelerator are spinning at a speed close to light.

Portugal has participated in experiments with two LHC particle detectors (ATLAS and CMS) through the Laboratory of Instrumentation and Experimental Particle Physics (LIP), which scientifically represents the country at CERN.

Once the accelerator is upgraded, LIP, as announced in today’s statement, will participate in experiments with a new detector for neutrinos, particles similar to electrons, but without electric charge and with a very low mass.

According to CERN, this detector will be able to detect new particles, in the case of “interacting very weak particles not predicted by the Standard Model” that may “form dark matter,” which scientists estimate will make up 84.5% of the total. Matter in the universe that is inferred by the effect of gravity on visible matter, such as galaxies and stars.

Together, dark matter and dark energy, assumed by physical theories, make up 95% of the universe. The remaining 5% corresponds to the visible substance, explained by the standard model, and confirmed in experiments at the LHC.

The world’s largest and most powerful particle accelerator is more than 10 years old, and “life expectancy” to 2040.

Decisions will have to be made in 2025 on building a new particle accelerator.

In June 2020, the Council of CERN, where Portugal has a seat as a member state, tasked the European Particle Physics Laboratory with directing the technical and financial feasibility of building a new, 100-kilometre circular accelerator, within five years. A tunnel capable of operating at 10 times the energy of the LHC.

Particle physics technology, using proton beams, is used in many countries to treat some types of cancer.

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