As construction of the World`s largest machine, the Large Hadron Collider (LHC) at CERN in Geneva (Switzerland), gears up for completion next year, the four main experiments, that will study different aspects of the resulting high-energy particle collisions, are also gearing up. For one such experiment, called ALICE, this process got a step closer last week when a crucial part of the 10,000-ton detector, the British-built Central Trigger Processor (CTP), was installed in the ALICE cavern, some 150 feet underground.
"The CTP is essentially the electronic brain of the whole ALICE experiment", says Dr David Evans of the University of Birmingham, "it can receive up to 60 input signals from various sub-detectors and sensors every 25ns (25 billionths of a second) and make complex decisions in less than 100ns (a tenth of a millionth of a second). The CTP decides if an interesting particle collision has taken place and tells the many sub-detectors of ALICE whether to collect the data or not."
The ALICE experiment will probe the mysteries surrounding the structure of matter. Head-on collisions of lead nuclei at the LHC will create sub-atomic sized fireballs with huge temperatures and densities and recreate the conditions that existed less than a millionth of a second after the Big Bang.
"These 'mini Big Bangs' will produce temperatures of over a trillion degrees - 100,000 times hotter than the centre of the Sun – and neutrons and protons (which make up the nuclei of atoms) are expected to 'melt' into a new state of matter – the quark-gluon plasma.", says Dr. Evans, "By studying this we hope to learn more about the force that holds atomic nuclei together (the strong force), the origin of the mass of nuclear matter and much, much more."
The Birmingham group and the UK subscription to CERN are funded by the Science and Technology Facilities Council.
Notes for Editors
Images of ALICE, Credit Science and Technology Facilities Council.
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Dr Evans and students with the Central Trigger Processor
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The detectors are being installed inside the huge ALICE magnet (red). When complete, the whole experiment will weigh about 10,000 tens.
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Dr. David Evans takes a close look at tracks from a simulated collision in ALICE.
For more information, contact:
Julia Maddock|, Press Officer
Science and Technology Facilities Council
Tel 01793 442094
Dr. David Evans|, School of Physics and Astronomy, The University of Birmingham.
Tel. 0121 414 4227
Mobile: 0798 040 6171
Background information on ALICE
ALICE is one of the four main experiments at the CERN LHC (link opens in a new window)| and will study the physics from ultra-high energy proton-proton and lead-lead interactions. ALICE will explore conditions in the first instants of the Universe, a few microseconds after the Big Bang, when matter was in its primordial state, a 'soup' of fundamental particles called quarks and gluons.
Physicists working on the ALICE experiment will study the properties, still largely unknown, of this state of matter, called a quark-gluon plasma, in order to understand more about:
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The strong force and how it governs matter;
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The nature of the confinement of quarks – why are quarks confined in matter, such as protons?
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Why do quarks have a much larger mass when confined in particles such as protons and neutrons?
The ALICE Collaboration consists of around 1000 physicists and engineers from about 90 institutes in 30 countries. The team from the University of Birmingham, consisting of 10 physicists and engineers, is the only UK group involved in ALICE but plays a vital role being responsible for the design and construction of the central trigger electronics and corresponding software. In addition, the UK group is already making an important contribution to the preparations for analysing the data expected in 2008.
The ALICE detector is the result of 17 years R&D and development. It is placed in the LHC ring, some 150 feet (50 metres) underground, is 52 feet (16 metres) high, 85 feet (26 metres) long, and weighs about 10,000 tons.
During collisions of lead nuclei, ALICE will record data to disk at a rate of 1.2 GBytes (2 CDs) every second and will write over 2 PetaBytes (2 million GBytes) of data to disk every year; that's equivalent to more than 3 million CDs (or a stack of CDs (without boxes) three miles high). To process these data, ALICE will need about 50,000 top-of-the-range PCs, from all over the world, running 24 hours a day.
ALICE utilises state-of-the-art technology including high precision systems for the detection and tracking of subatomic particles, ultra-miniaturised systems for the processing of electronic signals, and a worldwide distribution network of the computing resources for data analysis (the GRID). Many of these technological developments have direct implications to everyday life such as medical imaging, microelectronics and information technology.
For more information, visit the ALICE (link opens in a new window)| web page.
For more information on the LHC at CERN (link opens in a new window)|
