How the Large Hadron Collider works

Located at CERN (the European Organization for Nuclear Research) near Geneva, Switzerland, the LHC consists of a 27-kilometer circular tunnel buried 100 meters underground. This cutting-edge machine allows physicists to study the interactions of subatomic particles by accelerating them to nearly the speed of light and colliding them.

1. The Purpose of the LHC

The LHC was built to investigate the fundamental questions of physics. Scientists use it to test the predictions of the Standard Model, discover new particles, and explore concepts such as dark matter, antimatter, and extra dimensions. One of its most famous achievements was the discovery of the Higgs boson in 2012, which confirmed how particles acquire mass.

2. How the LHC Accelerates Particles

The LHC accelerates protons or heavy ions through a series of smaller accelerators before injecting them into the main ring. The process involves:

a. Generating the Particles

The LHC typically starts with hydrogen gas, stripping electrons from hydrogen atoms to leave behind protons. These protons serve as the primary particles for acceleration.

b. Pre-Acceleration Stages

Before entering the main LHC ring, the protons pass through a series of smaller accelerators:

Linear accelerator (Linac 4) – Gives the protons an initial push.

Booster – Increases their speed further.

Proton Synchrotron (PS) – Raises the energy level significantly.

Super Proton Synchrotron (SPS) – Brings the protons to a high-energy state before injecting them into the LHC ring.

c. The Main Acceleration in the LHC Ring

Once inside the LHC, superconducting magnets guide the particles along the circular tunnel. These magnets operate at extremely low temperatures (-271°C, just above absolute zero) using liquid helium to maintain superconductivity. The radiofrequency cavities provide the energy boost needed to accelerate the protons to nearly the speed of light.

3. The Collision Process

The LHC has four main collision points, where two beams of protons moving in opposite directions are brought into a head-on collision. These points are housed within large detectors:

ATLAS and CMS: General-purpose detectors for studying a wide range of particles and interactions.

ALICE: Focuses on the study of heavy-ion collisions to understand quark-gluon plasma.

LHCb: Specializes in studying matter-antimatter asymmetry.

When protons collide, they release enormous energy, breaking apart into fundamental particles. Scientists analyze the data from these collisions to discover new particles and confirm existing theories.

4. Data Collection and Analysis

Each second, the LHC generates millions of collisions, producing vast amounts of data. Specialized detectors capture this data, which is then analyzed by a global network of computers called the Worldwide LHC Computing Grid. Advanced machine learning and algorithms help identify rare events and potential new discoveries.

5. Achievements and Future Plans

Since its activation in 2008, the LHC has made groundbreaking discoveries, including:

Higgs boson (2012) – Provided evidence for the mechanism that gives particles mass.

Exotic particles – Such as pentaquarks and tetraquarks, which deepen our understanding of subatomic structures.

Matter-antimatter asymmetry studies – Helping to explain why the universe is mostly made of matter rather than antimatter.

Looking forward, CERN is working on the High Luminosity LHC (HL-LHC) upgrade, expected to begin operations in 2029. This upgrade will increase the collision rate, allowing for even more precise measurements and potential new discoveries.

Conclusion

The LHC is one of humanity’s greatest scientific achievements, providing deep insights into the nature of reality. By accelerating and colliding particles at unprecedented energies, it continues to push the boundaries of physics, answering fundamental questions about the universe’s origin and structure.