World's biggest experiment begins

The tunnel is home to a giant particle accelerator, the flagship facility of CERN, the European Laboratory for Particle Physics. In the ATLAS experiment, particles will be fired towards each other at speeds of more than 600 million miles an hour. Their collisions will be recorded by a semiconductor tracker - essentially an ultra-sensitive digital camera - which can take 40 million pictures in a second and measure particle paths to an accuracy of a tenth of the width of a human hair.

Currently, the tracker is being used to record the paths of 'cosmic rays' - particles arriving naturally at the Earth from outer space. However, when the massive machinery starts to work fully, much more complicated images will be taken, and their analysis could be hugely important.

It is hoped that the effects of the collisions of particles will help to track down the Higgs Boson - thought to be the only type of basic particle yet to be discovered. The massive amounts of energy that will be generated by the particle accelerator may also be enough to produce so-called 'dark matter', which astronomers believe makes up a large part of the universe and is responsible for the movements and arrangement of stars and galaxies.

UCL has been involved throughout the development of the experiment and the collosal machinery involved in its execution. The High Energy Physics group at UCL Physics & Astronomy was involved in developing the electronics behind the semiconductor tracker, as well as playing a role in the electrical and mechanical engineering required to construct the particle detector.

ATLAS is a collaborative project involving research groups from around the world. There are 1,800 physicists (including 400 students) participating from more than 150 universities and laboratories in 35 countries.

Dr Alan Barr, a member of the UCL High Energy Physics group, said: "It is great news that after decades of research and planning, we finally know that the machinery we have helped to develop is working. What is really exciting is that, within a year, when the machinery is fully operational, we will be able to explore the most fundamental constituents of the universe."

• Links:
• UCL High Energy Physics Group
• The ATLAS experiment