In 2012, CERN researchers discovered a particle consistent with the Higgs boson – nicknamed the “God Particle” – and scientists celebrated a historical moment in physics. Now, composites have entered the story, as research on the Higgs boson, extra dimensions and dark matter at CERN (the European Council for Nuclear Research) restarts after a two-year hiatus. During that time, improvements were made on the laboratory’s particle accelerator, the Large Hadron Collider (LHC). The LHC, the world’s largest and most powerful particle accelerator, has received CFRP upgrades in its ATLAS detector, one of two general-purpose detectors within the LHC.
At 151 x 82 x 82 feet, the 7,000-ton ATLAS detector is the largest volume particle detector ever constructed. It sits 328 feet below ground near the main CERN site, close to the small town of Meyrin, Switzerland. The LHC yielded the first discovery of a particle consistent with the Higgs boson, a particle that gives all matter mass and can explain why some particles have mass despite properties that should require them to be massless.
If it’s been a while since you’ve taken a course in physics, you may be wondering what are particle accelerators and detectors? In simple terms, a particle accelerator is a machine that accelerates particles to extremely high velocities using electric or electromagnetic fields. The LHC at CERN is in a subset of accelerators known as colliders. As the name suggests, particles within these accelerators crash or collide together. When that occurs, detectors such as the ATLAS detector then gather information about the particles, including their speed, mass and charge. Such collisions allow scientists to study the subatomic world and the laws governing it.
Over the past two years, the LHC was upgraded to accommodate higher collision energies. As part of the upgrade, CERN contacted Teufelberger Service GmbH, a manufacturer based in Wels, Austria, for a specific component at the center of the ATLAS detector. The lightweight CFRP piece is a 5-meter high-tenacity carbon fiber support structure with an epoxy resin system selected for its radiation resistant properties. Toray supplied the carbon fiber.
The CFRP component supports both a specialized subdetector and the beam tube where the particles are moving, and must hold the detector elements in place. The original component was made from aluminum because of its light weight. However, aluminum did not provide all of the necessary properties. “The aluminum allowed for a little deflection, or shifting, of this pipe during the experiment, which is not ideal,” says Herwig Kirchberger, head of the composite business unit at Teufelberger. “But the most severe issue was that the aluminum structure was contaminated with radioactive particles, and this was the main reason for CERN’s switch to carbon fiber.” Kirchberger explains that carbon fiber’s lower mass absorbs less radiation.