Public Release:  Where has all the antimatter gone?

VELO seeks the answer

Science and Technology Facilities Council

Scientists from the Universities of Liverpool and Glasgow have completed work on the inner heart of an experiment which seeks to find out what has happened to all the antimatter created at the start of the Universe. Matter and antimatter were created in equal amounts in the Big Bang but somehow the antimatter disappeared resulting in the Universe, and everything in it, including ourselves, being made of the remaining matter.

The final modules of the VErtex LOcator (VELO), a precision silicon detector, have been delivered to CERN, the European Particle Physics Laboratory in Geneva. Once assembled VELO will be installed into the LHCb detector, one of four experiments, which make up the Large Hadron Collider (LHC) particle accelerator, which is due to be switched on in November this year.

LHCb is designed to investigate the subtle differences between matter and antimatter in particles containing b (beauty) quarks. The VELO is an essential part of the experiment which will provide the unprecedented precision necessary to isolate them. The LHC, located in a 27km underground tunnel which straddles France and Switzerland, will help answer some of the fundamental questions about the origins of our Universe and is set to change the future path of particle physics research.

Within the LHC, two beams of protons will be accelerated to close to the speed of light and then collided in one of the four experiments, which will each measure the outfall of particles.

Professor Themis Bowcock, lead scientist from the University of Liverpool LHCb team said, "The VELO gives us the precision we need not only to identify b quarks in a proton-proton collision, but to do so in real time. This allows us to isolate samples of b quarks for analysis in a way that would be impossible otherwise. It is the key to LHCb's physics aims."

The VELO is unique in its design with the whole device (about a metre long) consisting of 42 silicon "modules", spread along both sides of the proton beam (21 each side). The VELO actually sits inside a vacuum vessel - with a thin sheet of aluminium, know as RF foil, separating it from the primary vacuum inhabited by the proton beams. The two halves of modules are mechanically moved in to within 7mm of the beam during data-taking, and out to a safe distance afterwards.

Dr Tara Shears, LHCb scientist from the University of Liverpool explains, "To achieve optimal precision the silicon detectors need to be as close as possible to the beam. When operational 40 million proton proton interactions will occur per second inside LHCb and it is no mean feat that measurements of these collisions will take place in real time.

Like all the detector experiments at CERN a worldwide team of scientists are involved in the design and construction of LHCb. The experiment involves 663 scientists from 47 institutes and universities in 15 countries. UK collaborators make up around 20% of this. The individual VELO modules, of which there are 42 in total, were designed and assembled at the University of Liverpool in a state of the art clean room.

Transport of the completed VELO modules from the University of Liverpool occurred by less than traditional means. Each module being couriered via an easyJet flight to Geneva! However, with the onset of tighter baggage restrictions some of the modules made the 1,066 km (663 mile) journey in the boot of a car.

Scientists from the University of Glasgow are responsible for the reception and testing of the modules at CERN. Dr Chris Parkes from University of Glasgow said, "Now that all 42 modules are on site we are busy testing before final installation in the detector, 100 metres underground.



Kate Spark - University of Liverpool Press Office
Tel: 0151 794 2247

Martin Shannon - University of Glasgow Press Office
Tel: 0141 330 8593

UK Science Contacts
Professor Themis Bowcock - Lead LHCb scientist at the University of Liverpool
Tel: 0151 794 3315

Dr Tara Shears - LHCb scientist, University of Liverpool
Tel: 0151 7943315

Dr Chris Parkes - LHCb scientist, University of Glasgow
Tel: 0141 330 5885

Notes to Editors
Websites - including images of LHCb and VELO
CERN website -
UK LHC website -
University of Liverpool VELO website -
LHCb public page -

The University of Liverpool is one of the UK's leading research institutions. It attracts collaborative and contract research commissions from a wide range of national and international organisations valued at more than £100 million annually.

Science and Technology Facilities Council

  • The Science and Technology Facilities Council ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge-exchange partnerships.

  • The Council has a broad science portfolio including Astronomy, Particle Physics, Particle Astrophysics, Nuclear Physics, Space Science, Synchrotron Radiation, Neutron Sources and High Power Lasers. In addition the Council will manage and operate three internationally renowned laboratories:
  • The Rutherford Appleton Laboratory, Oxfordshire
  • The Daresbury Laboratory, Cheshire
  • The UK Astronomy Technology Centre, Edinburgh
  • The Council gives researchers access to world-class facilities and funds the UK membership of international bodies such as the European Laboratory for Particle Physics (CERN), the Institute Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF), the European organisation for Astronomical Research in the Southern Hemisphere (ESO) and the European Space Agency (ESA). It also contributes money for the UK telescopes overseas on La Palma, Hawaii, Australia and in Chile, and the MERLIN/VLBI National Facility, which includes the Lovell Telescope at Jodrell Bank Observatory.

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