Friday 28 February 2025
The Compact Muon Solenoid (CMS) experiment at CERN’s Large Hadron Collider is one of the most complex and sophisticated particle detectors in the world. Its massive magnet, which generates a powerful magnetic field to bend and measure subatomic particles, has been precisely mapped for years. But a recent study reveals that this map wasn’t entirely accurate – and it’s not just a small mistake.
The CMS team used a clever trick to check their magnetic field map: they rapidly discharged the magnet’s superconducting coil while measuring the resulting magnetic flux density in the steel yoke blocks that make up the magnet. This allowed them to compare the measured values with those predicted by the team’s simulations. The results were surprising – the measurements showed significant discrepancies between the actual and simulated magnetic fields, particularly near the edges of the yoke blocks.
It turns out that these edge effects are caused by eddy currents, which are electrical currents induced in conductive materials like steel when they’re exposed to changing magnetic fields. These currents can significantly alter the local magnetic field, making it harder for particles to be accurately tracked and measured.
To compensate for this effect, the CMS team has refined their magnetic field map, taking into account the eddy current contributions. This new map is much more accurate than its predecessor, with an error margin reduced from 3% to just 1%. The implications are significant – this level of precision is essential for the LHC’s high-energy particle collisions, which require precise tracking and measurement of subatomic particles.
But why does this matter? Precise control over the magnetic field allows scientists to better understand the fundamental forces of nature. By accurately measuring particle trajectories, researchers can gain insights into the properties of quarks and gluons, which are the building blocks of protons and neutrons. This knowledge will help us better understand the universe’s earliest moments, including the Big Bang itself.
The CMS experiment is just one of many ongoing research projects at CERN, but its importance cannot be overstated. By pushing the boundaries of technological innovation and scientific understanding, experiments like CMS pave the way for future discoveries that could revolutionize our understanding of the cosmos.
Cite this article: “Refining the Magnetic Field Map: A Crucial Step in Particle Detection”, The Science Archive, 2025.
Compact Muon Solenoid, Large Hadron Collider, Magnetic Field, Particle Detector, Superconducting Coil, Eddy Currents, Steel Yoke Blocks, Cern, Quarks And Gluons, Big Bang
