Collisions between proton beams and oxygen ions began on June 29 at the Large Hadron Collider (LHC), marking the start of a series of experimental tests involving oxygen-oxygen and neon-neon collisions.
The first oxygen collisions at the LHC
This special campaign, scheduled to last until July 9, represents a crucial breakthrough for the study of the strong interaction, the quark-gluon plasma and the internal structure of cosmic rays.
The main challenge of these tests lies in the difference between the charge-to-mass ratios of protons and oxygen ions. To ensure that the beams collide at the desired points, CERN engineers have carefully synchronized the frequency of revolution of each beam. The goal: to ensure that the impact occurs at the heart of the main LHC detectors (ALICE, ATLAS, CMS and LHCb), maximizing the quality of the data obtained.
In addition to the core experiments, the campaign includes LHCf, which focuses on the study of cosmic rays by detecting small-angle particles. This experiment is using a detector installed 140 meters from the ATLAS collision point. ATLAS collision point to analyze proton-oxygen collisions. It will later be replaced by a calorimeter for oxygen-oxygen and neon-neon collisions.
During this campaign, a crystal collimation system is also being evaluated. This system seeks to improve the efficiency in removing stray particles (halos) that affect the accuracy of the ion beams. These tests could have implications for future upgrades of the accelerator safety system.
One of the effects observed is the “transmutation” of the oxygen beam: after several hours of use, collisions generate particles with the same charge-to-mass ratio, contaminating the original beam. This phenomenon makes it necessary to eject and inject new beams to maintain experimental purity and quality.
The commissioning of this collision sequence is the result of an adaptation process that began in April and required the specific configuration of several facilities of the complex: Linac3, LEIR, PS, SPS and finally the LHC. The goal is to generate experimental data that will allow refining current models of high-energy physics and primordial matter in the universe.
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Source and photo: CERN
