Interactions News Wire #69-05
24 August 2005 http://www.interactions.org
Content: Press Release
Date Issued: 24 August 2005
24th August 2005
87/05Bon Voyage - heart of
world's biggest physics experiment leaves the UK
After years of painstaking effort, the last of the 4 barrels that make
up the central part of the Semiconductor Tracker (SCT), the heart of the
biggest physics collaboration in the world has today (August 24th) left
Oxford for its new home at the European Particle Physics Laboratory,
CERN, near Geneva.
At CERN, physicists from around the world are assembling the Large
Hadron Collider (LHC) which will send two counter-rotating beams of
particles round an underground ring at 99.999999 per cent of the speed
of light. When the beams are brought into collision, a shower of new
particles will be produced reproducing conditions similar to those
immediately after the Big Bang. These will be studied at four detectors
around the ring. The largest of these detectors is called ATLAS and at
its heart lies the SCT tracking the movements of the charged particles
produced in the high-energy collision.
The SCT detector consists of a central region and two end caps. The
central region is formed of four concentric barrels, covered with 2112
silicon modules (30 square metres worth!). The modules were produced by
collaborators in different countries and sent to the University of
Oxford for precision assembly. To be assembled, each of the fragile
silicon modules had to be mounted on an ultra-lightweight carbon fibre
cylinder using a specialised robot.
Each silicon module has 1536 channels, where each channel is a separate
detector element which is connected by a wire bond to an individual
channel of an ASIC (application specific integrated circuit) which
contains all the read out electronics. Dr Richard Nickerson, who led
assembly of the SCT at Oxford, said "the assembly of the SCT barrels
has proved to be a very challenging project and so we are all extremely
pleased to see it reach a successful conclusion with 99.5% of the 3
million channels working - even more than we hoped for as we had built
in an element of redundancy."
Dr Tony Weidberg, also University of Oxford, said, "It has been both
a privilege and a challenge to play our part in the world's largest
physics collaboration. We now eagerly await the full assembly of the
Atlas detector and the start of the LHC in two years time which will
allow us to better study the nature of the Universe."
The SCT will track the positions of charged particles passing through
the detector with an accuracy of better than 20 microns (less than the
diameter of a human hair) over one metre. A superconducting solenoid
will provide a magnetic field of 2 Tesla so from these measurements it
will be possible to calculate the momentum of the particles, an
important clue in sorting through the debris of a high energy particle
collision. This information forms a crucial part of the data gathered
by the full ATLAS Detector system and will be essential in the task of
unravelling the physics in these complex events.
Other sections of the Atlas detector will pick up other particle
properties. Between them, the different sections should allow a complete
picture to be formed.
"The LHC will be the world's primary experiment to probe the
structure of matter and forces of nature when it becomes operational in
2007," said Professor Keith Mason, CEO of the Particle Physics and
Astronomy Research Council (PPARC) which funds UK involvement in CERN.
Professor Mason added "UK research groups are involved in each of the
LHC's four detectors and the SCT is a clear example of our technical
The ATLAS experiment is the world's largest collaboration in physical
sciences, involving more than 1800 scientists from around the world. The
detector is a leviathan, measuring 44m long and 22m high, as large as a
five-story building, and weighing 7000 tons. Yet at its heart, where the
SCT will operate, narrow beams of particles will be focussed to collide
in an area much less than 1 square mm. Out of nearly 1000 million
collisions a second, only a few will have the special characteristics
that might lead to new discoveries.
Notes for Editors
The SCT is a collaborative international project with UK physicists
coming from university research groups at: Birmingham, Cambridge,
Glasgow, Lancaster, Liverpool, Manchester, Oxford, Queen Mary University
of London, Rutherford Appleton Laboratory, Sheffield and University
Images are available to download from http://www.pparc.ac.uk/Nw/BonVoyageSCT.asp
PPARC Press Office
Tel 01793 442094
Dr. Tony Weidberg
University of Oxford
Tel: 01865 273370
University of Oxford Press Office
Tel: 01865 280534
The Particle Physics and Astronomy Research Council (PPARC) is the UKs
strategic science investment agency. It funds research, education and
public understanding in four areas of science - particle physics,
astronomy, cosmology and space science.
PPARC is government funded and provides research grants and
studentships to scientists in British universities, gives researchers
access to world-class facilities and funds the UK membership of
international bodies such as the European Laboratory for Particle
Physics (CERN), and the European Space Agency. It also contributes money
for the UK telescopes overseas on La Palma, Hawaii, Australia and in
Chile, the UK Astronomy Technology Centre at the Royal Observatory,
Edinburgh and the MERLIN/VLBI National Facility, which includes the
Lovell Telescope at Jodrell Bank observatory.
PPARC's Public Understanding of Science and Technology Awards Scheme
funds both small local projects and national initiatives aimed at
improving public understanding of its areas of science.