The Compact Muon Solenoid (CMS) experiment is one of the four main experiments at the Large Hadron Collider (LHC) — the world’s largest particle accelerator, housed underground near the France-Switzerland border near Geneva. The experiment, which consists of a roughly 69 feet long and a 50 feet wide detector located 300 feet below the ground, was crucial in the discovery of the Higgs boson in 2012.
This week, the experiment was given a major upgrade — one that scientists at the European Organization for Nuclear Research (CERN) likened to an “open-heart surgery.” On Thursday, engineers at CERN finished the installation of a new “pixel tracker” — a detector that is a key part of CMS’ particle tracking system.
“The heart of the CMS experiment is the pixel detector, the innermost instrument in the very heart of the CMS apparatus, the very point where new particles, such as the Higgs boson, are produced by the energy of the proton proton collisions of the LHC accelerator,” CERN explained in a press release. “With thousands of silicon sensors, the new Pixel Tracker is now being upgraded to improve the particle-tracking capabilities of CMS.”
The upgrade would allow the detector to record over 120 million pixels at 40 million frames per second. This, in turn, would allow CMS to create superimposed pictures of 50 to 60 proton collisions — much higher than the 25 to 30 superimposed pictures the previous 66 megapixel detector was capable of creating.
The LHC, which consists of a 17-mile-long ring of superconducting magnets, is the world’s most powerful particle accelerator. Beams of high-energy particles (hadrons, which are composite particles containing quarks) circulate inside the ring and are made to collide at four locations corresponding to the positions of four of its main particle detectors – ATLAS, CMS, ALICE and LHCb.
The CMS is built around a huge solenoid magnet that takes the form of a cylindrical coil of superconducting cable capable of generating fields up to 100,000 times stronger than the magnetic field of Earth.
Scientists hope that increasing the detector’s resolving power would finally reveal signs of the so-called “new physics” — one that lies beyond the Standard Model, which is a framework that best describes three of the four known fundamental forces in the universe.
In 2012, with the discovery of the Higgs boson — responsible for imparting mass to all other particles — scientists believed the last missing piece that completed the Standard Model had been found. However, even the completed version of this theory fails to incorporate gravity, and explain the origin and preponderance of dark matter and dark energy in the universe.
Once the LHC restarts later this year, the upgraded CMS may finally help reveal chinks in the armor of the Standard Model and even discover particles predicted by supersymmetry, which posits the existence of more massive “super partners” for every known particle.
“We have to make sure that our detectors can keep up with what's being thrown at them,” Austin Ball, the technical coordinator for the CMS experiment, told BBC News. “The performance of the accelerator has improved so rapidly over the past couple of years that this is the time we need to make the change to exploit the accelerator's full potential - for new physics, and the study of existing physics.”