Wednesday, August 10

The LHC begins to collect data at record energies

After the celebrations of tenth anniversary of the discovery of the Higgs boson, on Tuesday, July 5, 2022, a new data collection period begins for the experiments of the most powerful particle accelerator in the world, the Large Hadron Collider (LHC) of the CERNafter more than three years of updating, improvement and maintenance work.

The beams have already been circulating around the CERN accelerator complex since April, with the LHC and its injectors started up to operate with new beams of greater intensity and energy. Now, the LHC operators are ready to announce “steady beams,” a condition that allows the experiments to turn on all of their subsystems and start taking data that will be used for analysis of the collected physics.

The LHC will operate 24 hours a day for approximately 4 years, at a record energy of 13.6 trillion electron volts (TeV), approaching the maximum it can operate at (14 TeV).

The LHC will operate 24 hours a day for approximately four years, at the record energy of 13.6 teraelectron volts (TeV)

“We will focus the proton beams at the interaction points down to a beam size of less than 10 microns, to increase the collision rate. Compared to the first data collection period (Run 1), in which the Higgs boson was discovered with 12 reverse femtobarns, in Run 3 we will work with 280 reverse femtobarns, a significant increase that opens the way to new discoveries” says director of accelerators Mike Lamont. An inverse femtobarn is a measure of the number of collisions or the amount of data collected, corresponding to about 70 trillion proton-proton collisions.

Live broadcast of the start of Run 3

The start of Run 3 has been broadcast live today through CERN’s channels and social networks. Live commentary in five languages ​​(including Spanish), made from the CERN Control Center, have guided viewers through the different stages of the accelerator’s operation, from the moment the beams are injected into the LHC until they collide at the four points of interaction where the detectors.


The four major experiments at the LHC have undergone major upgrades to their data reading and selection systems, with new detection mechanisms and computing infrastructure.

detectors ATLAS Y cms they expect to record more collisions during Run 3 than in the previous two physics cycles combined. The experiment LHCb has been completely revamped and expects to multiply its data collection rate by 10, while ALICE aspires to multiply by 50 the number of registered collisions.

The improvements implemented in the detectors of each experiment will allow to collect data samples significantly larger and of higher quality compared to previous periods of operation.

The improvements implemented in the detectors of each experiment will allow the collection of significantly larger and higher quality data samples compared to previous periods of operation.

By increasing the data sample and using higher collision energies, Run 3 aims to further expand the LHC’s already diverse physics program: scientific collaborations on the experiments will investigate the nature of the Higgs boson with a unprecedented precision, they will be able to observe previously inaccessible processes and have the ability to improve the precision of measurements taken on many known processes that address fundamental questions, such as the origin of the matter-antimatter asymmetry in the universe.

dark matter candidates

Furthermore, researchers are expected to be able to study the properties of matter under extreme conditions of temperature and density. Scientists will also search for dark matter candidates and other new phenomena, either through direct or indirect searches, in the latter case by more precisely measuring the properties of already known particles.

“We are looking forward to new data regarding the decay of the Higgs boson into second-generation particles, such as muons. This would be a completely new result in the Higgs boson saga, confirming for the first time that also second-generation particles gain mass via the Higgs mechanism,” says CERN theorist Michelangelo Mangano.

“We will measure the strength of the Higgs boson’s interactions with matter and force-carrying particles with unprecedented precision and will delve deeper into the search for Higgs boson decays into dark matter particles,” says Andreas Hoecker, spokesperson for ATLAS. .

One topic that will be closely watched is the study of rare processes in which a lepton flavor asymmetry (an unexpected difference between electrons and their parent particles, the muons) was observed in data collected by the LHCb experiment during the previous periods of operation of the LHC.

“The data acquired during this third cycle with our new detector will allow us to improve the accuracy by a factor of two and confirm or exclude possible deviations in the universality of the lepton flavor,” says Chris Parkes, spokesperson for the LHCb. Many of the theories that explain the anomalies observed by LHCb also predict new phenomena in different physical processes already known. These will be studied in ATLAS and CMS as well. “This complementary approach is essential: if we are able to confirm new phenomena in this way, they could be important discoveries in particle physics,” says Luca Malgeri, spokesperson for the CMS collaboration.

The ALICE programme, which focuses on the study of heavy ion collisions, will make it possible to investigate, with unprecedented precision, the quark-gluon plasma (QGP), a state of matter that existed in the first 10 microseconds after of the Big Bang.

“We hope to move from a phase where we observe many interesting properties of the quark-gluon plasma to a phase where we precisely quantify these properties and relate them to the dynamics of its constituents,” says Luciano Musa, spokesperson for the ALICE experiment.

In addition to studies using lead, a short period with oxygen collisions will be included for the first time, with the aim of exploring the appearance of QGP-like effects in other collision systems.

The smallest experiments at the LHC, these are TOTEM, LHCf, MODAL with your new MAPP subdetector, and the recently installed PHASE Y [email protected]they are also prepared to explore phenomena inside and outside the Standard Modelfrom magnetic monopoles, to neutrinos and cosmic rays.

Spanish research community

More than twenty Spanish research groups participate in international scientific projects that work with the data collected during the collisions that take place inside the LHC.

The broad and promising scientific program planned for this new physics season at the LHC keeps the Spanish community expectant and enthusiastic.

“We have been preparing for this new and exciting challenge for some time. Run 3 will provide greater sensitivity to phenomena not yet explored, will allow us to investigate the still little-known Higgs field in more detail and we hope that it will clarify the anomalies observed in some rare decays of heavy quarks”, explains Antonio Pich, director of the National Center of Particle, Astroparticle and Nuclear Physics (CPAN), which concludes: “We begin another exciting period of experimentation that can bring us great surprises”.

Font: CPAN



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