Particle beams are once again circulating in the world’s most powerful particle accelerator, CERN’s Large Hadron Collider (LHC).
A clockwise circulating beam was established on Friday, 20 November, and was followed by two circulating beams on Monday, 23 November, giving scientists their first chance to look for proton-proton collisions.
Particle physicists from the University of Liverpool are involved in ATLAS and LHCb, two of the four major LHC experiments. The team are now working towards analysing the first data from the collisions.
ATLAS is a ‘general purpose’ experiment built to search for evidence of the Higgs particle, Super-Symmetry and other new phenomena in the highest collision energies ever studied. One of the two end-caps on the semi-conductor tracker – at the heart of ATLAS – was assembled entirely at Liverpool.
LHCb is designed to investigate the subtle differences between matter and antimatter in particles containing b (beauty) quarks. Scientists hope to understand why, if the universe started in a Big Bang – which created equal amounts of matter and antimatter – today, all we can see is matter.
LHCb will look at the properties of particles containing b quarks and anti-b quarks to see where differences arise. To find these particles scientists need to use the high precision of the VELO – a particle detector, within the LHCb experiment, consisting of modules built by scientists, engineers and technical staff at Liverpool.
Professor Phil Allport, Head of the University’s Semiconductor Centre, said: “We are delighted to see particle collisions finally taking place inside the experiments at the LHC and to see the Liverpool-built components working exactly as they were designed to do. For many of us, this is the culmination of two decades of preparations.
“The innermost detector in the LHCb experiment is composed entirely of modules built at Liverpool and has already detected the first LHC beams.
“The ATLAS experiment contains the largest complete array of silicon detectors ever assembled in the UK. The 128,200 square centimetres ‘EndCap-C’ was built at the Liverpool Semiconductor Detector Centre.”
Next on the schedule is an intense commissioning phase aimed at increasing the beam intensity and accelerating the beams. By Christmas, the LHC should reach 1.2 TeV per beam, and have provided good quantities of collision data for calibration of the experiments in preparation for running collision energies of 7 TeV in 2010.