Posted on 02/12/2009
After a year of intensive repairs following a serious electrical problem in September last year, the Large Hadron Collider (LHC), the world’s most powerful atom smasher, is back in action.
The UK is one of the biggest contributors to the LHC project, which is based at CERN, the European Particle Physics Laboratory near Geneva in Switzerland. The project draws on the talents of Royal Holloway, University of London’s world-renowned physicists, who are excited about the restart of the biggest science experiment in the world.
The machine uses magnets to control beams of protons and send them in opposite directions through two parallel tubes. Each high energy proton to proton collision in the LHC will recreate conditions similar to those in the Universe immediately after the Big Bang.
The engineers have been working tirelessly and were able to circulate two counter-rotating proton beams and make them collide. At the machine’s relaunch, the first proton-proton collisions in the LHC were recorded by the massive ATLAS particle detector. The CMS experiment, the other large particle detector installed in the LHC ring, also recorded proton-proton collisions later on the same day.
The initial collisions were produced at a comparatively low energy, about half of the energy of the record-holding proton-antiproton collisions at the “TeVatron” collider in Chicago, US. In the next few weeks it is expected the LHC operators will be increasing the collision energy to a value in excess of the competing US collider.
Over the next two years it is planned the energy of the collisions at the LHC will be increased further, to reach the ultimate goal of collisions at the design energy of 14 million million electron-Volts - about 15 times higher energy than the initial collisions produced this week at the LHC.
These collisions mark the start of the data-taking era of the ATLAS and CMS experiments. After more than a decade of laborious construction of the experimental apparatus, the particle detectors will be starting on a long journey of exploration, recording billions of collisions every year, to unveil some of the remaining mysteries in Particle Physics.
Physicists will be sifting through the LHC data to search for evidence of rare processes, such as collisions containing the much-sought Higgs particle, which is believed to explain the origin of mass of all fundamental particles, or other more exotic theoretically-predicted particles, still to be observed experimentally.
Dr Pedro Teixeira-Dias, leader of the ATLAS group at Royal Holloway, said, “This is all very exciting. These successes at the LHC mark the start of a journey into new physics territory and are expected to lead to some major new scientific discoveries.”
ATLAS is an international collaboration of approximately 170 groups from Universities and research laboratories from all over the world, with the Royal Holloway Centre for Particle Physics being one of the founding groups of the ATLAS experiment.
Physicists in the Royal Holloway ATLAS group will be analysing the collisions collected by ATLAS with a view to search for the existence of the Higgs particle and the Graviton (the quantum of the gravitational force) and study in detail the properties of the top-quark (the heaviest fundamental particle known to date, which will be copiously produced in LHC collisions).
Professor Grahame Blair, leader of the Centre for Particle Physics at Royal Holloway, said, “This is great for the whole particle physics group. Our experimentalists, theorists, and accelerator scientists are all working hard at the LHC frontier; this is the first step of a very exciting journey.”
The Royal Holloway Centre for Particle Physics is a group of about 40 physicists carrying out a research programme in the related areas of theoretical particle physics, collider physics and accelerator science as part of the John Adams Institute, which is a joint venture between Royal Holloway and the University of Oxford.