What is particle physics?Particle Physics is a journey into the heartof matter. Using the biggest, mostsophisticated experiments, particlephysicists study the tiniest of particles tounderstand the nature and origins of theUniverse. UK scientists are at theforefront of particle physics research.

Council for the Central Laboratory of the Research Councils

CCLRC scientists are furthering theirunderstanding of the universe througha variety of large experiments. Thenature of mass, the differences betweenmatter and anti-matter, the oscillationsof neutrinos and the search for darkmatter are some of the highlights.The programme typically involves largefacilities shared between manycountries, with the European ParticlePhysics Laboratory (CERN), in Geneva,being the prime example.

CCLRC staff work with groups fromUniversities in the UK, providing engineeringand electronic expertise for the planning andconstruction phase, as well as operating andanalysing the data from the experiments.There are groups developing new sorts ofdetectors, and working on the ‘GRID’, acomputing infrastructure designed to shareprecious computing power worldwide.

CCLRC scientists are working on a newneutrino experiment at Fermi NationalAccelerator Laboratory (Fermilab), USA.The Main Injector Neutrino Oscillation Search(MINOS) is designed to study ghostlyparticles called neutrinos and in particular tostudy how the three different types are ableto transform one into the other.

Recently, research has started into how tobuild new types of particle accelerator. Oneexample is the International Linear Collider,a proposed machine with two giant electronguns, each over 10km in length, firingelectrons and positrons (their antimattercounterparts) to collide in the centre.Another is a new Neutrino Factory – aunique demonstrator is to be built at theCCLRC Rutherford Appleton Laboratory, inOxfordshire, to test the technology beforethe factory is built.

The CCLRC’s role in Particle Physics

A CCLRC scientist working on one of theATLAS detector modules. Courtesy CERN

The Large Hadron Collider (LHC) is anew, high energy particle collider beingbuilt CERN. It is the world’s largestinternational physics collaboration andwill help scientists to study thefundamental building blocks of ourUniverse, such as the nature of mass,the differences between matter andanti-matter and the search for ‘darkmatter’.

The LHC will be the highest-energy colliderever built, smashing together protonstravelling at 99.999999%of the speed of light!These collisions willproduce new particles,reproducing conditionssimilar to thoseimmediately after the BigBang, when the Universewas only a billionth of asecond old.

It will also help to shedlight on some of the most fundamentalquestions in science. Why is the Universemade predominantly of matter? Just afterthe Big Bang, the Universe was verydifferent – it was made up of equalamounts of matter and anti-matter.Scientists are looking for a mechanism toexplain the asymmetry seen today. Whydoes matter have mass? Scientists believethat a particle, the Higgs boson, isresponsible for giving all particles mass, butit has never been seen before. If such aparticle exists, the LHC will makeit detectable.

The visible matter in the Universe onlyaccounts for a tiny fraction of the total,leaving 96% of it unaccounted for. The LHCwill help us understand the nature of thismysterious ‘dark matter’ and whether thereis enough to keep the Universe expanding.

Four different detectors are beingconstructed to sift through the debris of

these collisions in the search fornew particles. CCLRC staff aretaking a leading role in the

construction and running of three of them.

The LHC experiments use several types ofdetector nested inside each other like a‘Russian Doll’, with the collisions occurringat the centre. The ATLAS detector is one ofthe largest – measuring 44m long and22m high, it is as large as a five storeybuilding! CCLRC staff have built 730 silicontracker modules for ATLAS – giant siliconchips, 12cm by 6cm, which record wherecharged particles pass through them.

Once collisions begin in 2007, eachexperiment will produce a data volumeequivalent to a one-mile-high pile ofcompact discs, every second! However, onlya fraction of this data actually contains newphysics: CCLRC scientists and engineers areleading the design and construction ofsome of the cutting-edge high-speedelectronics needed to sift through all thecollision data in order to keep theinteresting data for further analysis.

The CCLRC’s role in the Large Hadron Collider

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Above: Work on the SCT Barrel ofATLAS – part of the inner detector.

Left: Simulation by the ATLASexperiment of the decay of a Higgsboson into 4 muons (yellow tracks).

www.cclrc.ac.uk

The Council for the Central Laboratory ofthe Research Councils is one of eight UKresearch councils and is one of Europe'slargest multidisciplinary researchorganisations supporting scientists andengineers across the world. It operatesworld-class large scale research facilities,provides strategic advice to the governmenton their development and managesinternational research projects in support ofa broad cross-section of the UK researchcommunity.

Council for the Central Laboratory of the Research CouncilsChilton, Didcot, Oxfordshire OX11 0QX, UK

Tel: +44 (0)1235 445000 Fax: +44 (0)1235 445147

CCLRC Rutherford Appleton LaboratoryChilton, Didcot, Oxfordshire OX11 0QX, UK

Tel: +44 (0)1235 445000Fax: +44 (0)1235 445808

CCLRC Daresbury LaboratoryKeckwick Lane, Daresbury, Warrington,Cheshire WA4 4AD, UK

Tel: +44 (0)1925 603000Fax: +44 (0)1925 603100

CCLRC Chilbolton ObservatoryDrove Road, Chilbolton, Stockbridge,Hampshire SO20 6BJ, UK

Tel: +44 (0)1264 860391Fax: +44 (0)1264 860142

For further information and advicecontact:

CommunicationsCCLRC Rutherford Appleton LaboratoryChilton, Didcot, Oxfordshire OX11 0QX, UK

Tel: +44 (0)1235 445777Fax: +44 (0)1235 446665

Above: A CCLRC engineer testing oneof the main components of the CMSelectromagnetic calorimeter before itsinstallation at CERN.

Front page background picture: Simulated collision of two protons in theATLAS experiment. Courtesy CERN

Front page inset: The ATLAS experimentunder construction 100m below CERN.Courtesy CERN