Science and Technology Facilities Council
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ATLAS completes world’s largest jigsaw puzzle

Today (29th February) the ATLAS collaboration at CERN celebrates the lowering of its last large detector element. The ATLAS detector is the world’s largest general-purpose particle detector, measuring 46 metres long, 25 metres high and 25 metres wide; it weighs 7000 tonnes and consists of 100 million sensors that measure particles produced in proton-proton collisions in CERN’s Large Hadron Collider (LHC). The first piece of ATLAS was installed in 2003 and since then many detector elements have journeyed down the 100 metre shaft into the ATLAS underground cavern. This last piece completes this gigantic puzzle.

“This is an exciting day for us,” said Marzio Nessi, ATLAS technical coordinator. “The installation process is coming to its conclusion and we are gearing up to start a new programme of physics research.”

Known as the small wheel, this is the final element to complete the ATLAS muon spectrometer, and will be journeying 100 metres into its underground experimental cavern. There are two ATLAS small wheels, though small in comparison to the rest of the ATLAS detector, they are each 9.3 metres in diametre and weigh 100 tonnes including massive shielding elements. They are covered with sensitive detectors to identify and measure the momentum of particles that will be created in the LHC collisions. The entire muon spectrometer system contains an area equal to three football fields, including 1.2 million independent electronic channels. As particles pass through a magnetic field produced by superconducting magnets, this detector has the ability to accurately track them to the width of a human hair.

“These fragile detectors comprise the largest measuring device ever constructed for high energy physics,” said George Mikenberg, ATLAS muon project leader.

“One of the major challenges is lowering the small wheel in a slow motion zigzag down the shaft,” explained Ariella Cattai, leader of the small wheel team, “and performing precision alignment of the detector within a millimetre of the other detectors already in the cavern.”

Comprising 450 physicists from 48 institutions, the ATLAS muon spectrometer group includes members from China, France, Germany, Greece, Israel, Italy, Japan, Netherlands, Russia and the United States of America. For them, this event marks the end of more than a decade of development, planning and construction of the muon spectrometer system. The shielding elements of the small wheels have been constructed in Armenia and Serbia.

The ATLAS collaboration will focus now on commissioning work in preparation for the start-up of the LHC this summer. Experiments at the LHC will allow physicists to take a big leap on a journey that started with Newton's description of gravity. Gravity is ubiquitous since it acts on mass, but so far science is unable to explain why particles have the masses they have. Experiments such as ATLAS may provide the answer. LHC experiments will also probe the mysterious dark matter and energy of the Universe, they will investigate the reason for nature's preference for matter over antimatter, probe matter as it existed close to the beginning of time and look for extra dimensions of spacetime.

Notes for Editors

Photo available from

http://press.web.cern.ch/press/PressReleases/Releases2008/PR02.08E.html

1. ATLAS is a worldwide collaboration comprising over 2100 scientists and engineers from 167 institutions in 37 countries and regions. These are Argentina, Armenia, Australia, Austria, Azerbaijan, Belarus, Brazil, Canada, Chile, China, Colombia, Czech Republic, Denmark, France, Georgia, Germany, Greece, Hungary, Israel, Italy, Japan, Morocco, Netherlands, Norway, Poland, Portugal, Romania, Russia, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Taiwan, Turkey, United Kingdom and the United States of America.

2. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

3. The LHC is a particle accelerator, which will be the world’s largest and most complex scientific instrument when it switches on in summer 2008.

Contact

CERN - Press Office
Tel: +41 22 767 2141/3432 - Fax: +41 22 785 0247 http://www.cern.ch/Press

renilde.vanden.broeck@cern.ch or press.office@cern.ch


Julia Maddock
STFC Press Office
Tel +44 1793 442094 Julia.maddock@stfc.ac.uk

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 manages and operates 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.
The Council distributes public money from the Government to support scientific research. Between 2007 and 2008 we will invest approximately £678 million.

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