Rights: The University of Waikato Published 17 September 2009 Download

Dr David Krofcheck explains what a particle accelerator is and how it works. He then goes on to explain how the world’s largest particle accelerator – known as the Large Hadron Collider – operates. The collider is 27km in circumference and can accelerate protons to extremely high kinetic energies. This allows physics to be explored in new regions of energy.

Point of interest
What is a superconducting magnet


What is a particle accelerator? It’s literally a method of taking a simple atom like hydrogen, but taking off the electron, so you just have one proton, and giving that proton energy of motion, giving it kinetic energy. The way to do that is you put it into a device which accelerates that proton to higher and higher velocity, and then you could either give that proton a boost of energy along the entire length of a straight line, or today, what we do, and a more common technique, is to put that proton in a ring, and each time that proton goes past a certain point, or various points, it gets a kick in energy, and they travel faster and faster and faster and so they accelerate to great velocities that way and then we smash them into a target and totally destroy them. We reserve the debris then from those collisions, and the pattern of the debris then tells us something about what kind of physics must have occurred at the point of collision.

What is the LHC? Why is it different? It’s just the world’s biggest, physically largest particle accelerator and it will accelerate protons to the highest energies that human beings have been able to achieve. Nature does it all the time with cosmic radiation coming in from space and hitting the Earth, but this is controlled by humans, so now we have some control over the beam energy and how many protons hit the target. So it’s a Large Hadron Collider – ‘hadron’ meaning strongly interacting particles, which is a proton. ‘Large’ is obvious – it’s 27 kilometres in circumference, 27 kilometres of superconducting magnets underground. It’s superconducting rather than making magnetic fields out of regular iron magnets the way nuclear physics and particle physics traditionally worked. Particle physics went into superconducting magnets to make stronger magnetic fields, more acceleration to the particles and explore higher energies and smaller distances.

LHC has taken that to the technological edge. So when you get the much higher energies and much smaller scales in length, you can explore physics in new regions of energy for which we can only theorise what might happen, and maybe we can find some new ways in which the particles interact and new particles that cause the interaction.

Elena Symeonidou,National Technical University of Athens, School of Applied Mathematical and Physical Science.
Philippe Mouche, CERN