Circular motion like (almost) never before...

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1 Case Study Getting the Measure of the Universe By Terry Sacks European particle physics laboratory CERN uses Leica Geosystems stateof-the-art laser tracker system to measure key components of the world s largest-ever particle accelerator. The European organisation for nuclear research, CERN, is the world s largest particle physics centre. Based near Geneva, the laboratory was founded in 1954 as one of Europe s first joint ventures, and has grown over the years into a foremost example of international scientific collaboration, now bringing together 20 member countries. To put it simply, CERN explores what matter is made of, and what holds it together. The laboratory provides state-of-the-art scientific facilities for researchers to use accelerators, which speed up minute particles to just under the speed of light, and detectors, to make the particles visible. Circular motion like (almost) never before... The laboratory, which has already pushed back the limits of scientific knowledge on many occasions over the last 50 years, is now busily preparing for the start of its biggest and most ambitious venture yet. The Large Hadron Collider, which is scheduled to open in 2007, will be the largest accelerator ever built. It will use an existing circular tunnel some 27 kilometres in length and 100m underground, which straddles the French-Swiss border and was previously home to the LHC s predecessor, the LEP. The aim of the venture is breathtaking in its ambition to bring subatomic particles into head-on collisions at higher energies than ever previously achieved, and thus to recreate the conditions existing at the time the universe was born. CERN European Particle Physics Laboratory

2 By so doing, scientists will be able to perform unprecedented research into several key theories that have to date only been proven on the blackboard. In particular, they will be able for the first time to create the conditions to test in the lab the mathematically fascinating theory of supersymmetry, which posits an underlying symmetry of all the basic physical forces from the nuclear forces within and between atoms, through electromagnetism to gravity (see box). Small is beautiful but tricky to measure... From micro-electronics to mechanical engineering, particle physics demands ultimate performance. At CERN, the exacting requirements of fundamental science have been pushing forward the limits of technology for nearly half a century. Much of the necessary expertise and corresponding heavy-duty manufacturing equipment is in-house, for instance at the CERN Magnet Assembly Factory, an industrial facility that manufactures the prototypes for the hundreds of dipole magnets that are an essential part of accelerator systems. The high magnetic field produced by the dipole magnets curved to match the circular tunnel ensures the particles follow an equally circular trajectory. For some tasks, however, outside expertise is still required. A good example is the need for precision measuring equipment to ensure the dipole magnets are of exactly the right geometry (shape). Since the dipole cold masses are not straight, but slightly bent in the horizontal plane, getting them to meet their very tight assembly tolerances of a 10th of a millimetre is not easy. Old school rulers replaced by Laser Trackers That is where the Leica LTD500 the world-wide proven instrument in a series of precision industrial laser tracker systems designed and manufactured by Leica Geosystems Metrology Division comes in. The LTD500 is a top-quality mobile co-ordinate measurement system used world-wide for high-accuracy assembly and inspection of product lines in industries ranging from aerospace and automotives to robotics and railways. It works by using what are known as interferometric techniques interference of light waves is used to measure precise distances. For the geometry measurements of the dipole magnets, a mechanical mole a small tool that crawls through the magnet s tubes centred with respect to the dipole s cold bore tubes holds a reflector as a target while it travels. The position of this reflector defines the axis of the cold bore tube and is measured with the LTD500 in a Cartesian co-ordinate system. The reason such specialised equipment is required for these measurements is that the dimensions of the magnets are so extreme the inner diameter of the cold bore tubes is 50 mm, while the length of the cold mass is 15 metres. In fact, CERN project staff say there is nothing else on the market that can even come close to the LTD500 in its ability and its accuracy to get the dipole cold mass geometry measurements done. That is why they have bought a total of nine LTD500s since October 1999, of which the latest two were commissioned in April Project engineers Marta Bajko and Ans Pardons say: We are aiming for one order of magnitude better than that which we actually need for the accuracy of the measurements, and old school rulers of any sort cannot handle these requirements. For our work we need to rely on optical measuring technology. Optics mean accuracy, and the LTD500 is giving us the accuracy we need. Marta adds: With 1200 plus magnets ahead of us, there is a lot to do, but with LTD500 by our side, I have no doubts whatsoever that all will go well. CERN European Particle Physics Laboratory

3 «Optics mean accuracy, and the LTD500 is giving us the accuracy we need.» Leica is measuring up to customer expectations... CERN, the world s largest particle physics research centre, has signed a contract to buy six more of Leica Geosystems state-of-the-art LTD500 laser tracker systems. With this order of new Laser Trackers, CERN also executed its right to extend the original terms of the initial 1999 contract with all its possible options. Using the LTD500 guarantees reduced production down-time, leading in turn to improved productivity and return on investment. In particular, it offers the following advantages: Flexibility: Lasers are notorious for calibration problems when constantly moved. However, the LTD500 is the exception that proves the rule the sturdiest laser tracker in existence, built with the express purpose of making it ultraportable. It can be mounted on specially-made height-adjustable stands, and the measurement head can also be positioned independently vertically. Real-time analysis: A unique measurement volume with a diameter of up to 70 metres allows the system to measure both small and large objects with up to micron accuracy. Surface inspections can be carried out with a measurement rate of up to 1000 points per sec- ond. Analysis software then presents actual-to-design deviations in real time, to determine out-of-tolerance areas. Alternatively, thousands of points can be delivered for reverse engineering. User-friendly automation: Complex structures and precision components, i.e. assembly boxes in the automotive industry or assembly tools in industry, can be inspected and built with high reliability. Periodic inspections, repeatability tests and other tasks are performed in a highly-automated way. Reliable hardware: The trackers high-speed tracking capability and proven reliable software satisfy the stringent requirements of machine guidance or calibration applications for instance, robot calibration, accuracy improvement of drilling machines or automation of wing to body assembly. Software integration: The system can now be fully integrated into companies manufacturing processes. Modules can be created for any application software to fully control it using international standards such as Excel, Word, Access and Visual Basic independent of the actual operating platform. The laboratory staff were impressed by the extent and quality of the training and general support offered by the vendor.

4 ...and quality service counts too As well as being highly satisfied with the technical precision of the LTD500 system, the laboratory staff were also impressed by the extent and quality of the training and general support offered by the vendor. For each tracker purchase, Leica Geosystems offered five full days training, plus several further routine visits to ensure maximum benefit was being obtained from the equipment. CERN, which is already the satisfied owner of nine LTD500s, besides other Leica metrology equipment namely the TDA5005 low cost tracker and several other lower-end surveying instruments has simultaneously announced the signature of a major long-term maintenance contract for all 15 precision measurement systems to ensure operational security and precise planning and control of maintenance costs. This maintenance contract represents a commitment by Leica Geosystems to guarantee the quality operation of its products for a total of 48 system years. Light at the end of the tunnel? The final decision will also hinge on the overall future financial position at CERN. Fundamental physics is an expensive business something that CERN became painfully aware of last year, when it was forced to revise the cost-to-completion of the LHC project, and put back the scheduled start date by about two years (to 2007). Even with a pre-built underground tunnel previously home to the LHC s predecessor, the LEP particle accelerator the LHC project is now expected to cost slightly more than 3 billion Swiss francs in total, compared to an original (1996) estimate of about 2.6 billion francs. The CERN budget is based largely on contributions from the 20 member countries, and they obviously require proof that the money is being wellspent. However, the LHC project is now well back on track, after CERN director-general Luciano Maiani produced a revised management plan, which will refocus laboratory resources onto the LHC project to the tune of 40 million Swiss francs a year half to come from non-lhc activities, the other half from a reduction in the projected future level of spending on the laboratory s Industrial Services division. Professor Maiani s plan, which was approved by the CERN Council in June 2002, is based on the belief that, despite some managerial and technical mis-assumptions with regard to the LHC, the project remains the future of CERN and the key to better understanding the universe (or universes?) in which we live... Using the LTD500 guarantees reduced production down-time, leading in turn to improved productivity and return on investment.

5 Life, the universe and the theory of everything? The so-called Standard Model of particle physics sees everything in the universe as comprised of a small number of irreducible point-like particles, including one which has not yet been detected. Twelve are known as fermions and divide equally between six quarks and six leptons. These in turn are grouped into three families, only one of which exists under normal conditions. These are the particles that make up familiar every-day matter. The remaining particles are known as bosons including the not-yet-discovered Higgs boson and are effectively manifestations of forces acting between the particles of matter. One of the cornerstones of the standard model is the underlying unity of two of the forces electromagnetism and the weak nuclear force. But it still leaves a number of key questions unanswered for instance, about such issues as why the world is made of matter rather than antimatter... One fascinating theory that the LHC hopes to put the test might answer many of these questions. Supersymmetry proposes that every particle in the standard model has a partner (known as a sparticle ). The resulting symmetry, while it doubles the size of the already-large particle zoo, would eliminate a number of unsatisfactory mathematical fudges that are necessary to justify the standard model and would go a long way to explain the existence of the still-mysterious Higgs boson. However, even if the scientists at CERN get that far, there will still be several questions left unanswered for their successors

6 Leica Geosystems Leica Geosystems is a leading developer, manufacturer and distributor of products, systems and software that capture, visualize and process spatial data through the employment of advanced technologies. Leica Geosystems supplies solutions to the varied users of spatial data. In several of these fields we hold the leading position in the world market. Headquarters Leica Geosystems AG Metrology Division Moenchmattweg 5 CH-5035 Unterentfelden Switzerland Phone Fax info.metrology@leica-geosystems.com Metrology Division The Metrology Division offers 3D measurement solutions for any demand in industrial processes, setting new standards for procedures in every major industry. Using state-of-the-art laser technology, we have made quality control and construction of large objects or small parts easier than ever before and accurate down to a few microns giving our customers unique advantages and cost savings in every field. Visit us at metrology For an updated reference list and additional addresses, please refer to our web site.