ESRF's giant ring is a dominant feature on the French landscape
The future development of one of Europe's scientific "crown jewels" may be affected by the current woes over the UK's physics budget.
The European Synchrotron Radiation Facility (ESRF) is a world-leading centre for the study of the structure of materials using intense X-ray beams.
Opened in 1992, it now needs a £150m upgrade to stay competitive.
Britain is a major partner; but with its physics funds under pressure, it is unclear how much the UK can contribute.
Germany, also, is unsure it can find the financing - but for the different reason of having committed itself to build another big facility for European member states.
"It's a critical time for the ESRF," said its director general, Professor Bill Stirling.
"If the reinvestment doesn't go ahead then this laboratory will remain competitive for some time, but eventually it will lose that edge, in particular to the very large Japanese and American facilities, both of which have similar reinvestment plans."
ESRF is an enormous machine based in the French city of Grenoble. It produces high-energy X-rays by firing electrons around an 850m-circumference, magnetised ring.
The radiation is guided down beamlines where it is used to reveal the atomic and molecular structure of sample materials held at experimental stations.
We want to be able to provide the tools for European and UK scientists
Scientists use this information in a host of ways - to design new drugs, develop better alloys, see inside fossil artefacts, and perfect new electronic components. The applications for synchrotron science are legion, and ESRF was built to give European researchers access to the very best equipment.
ESRF findings appear in some 1,500 peer-reviewed papers each year - and the UK is a big player. About a quarter of those papers will have at least one British co-author.
The UK's subscription accounts for about 14% of the ESRF budget, which means its contribution to the upgrade would come in at approximately £2m-a-year extra for the next 10 years.
The ESRF's X-rays penetrate amber to reveal ancient insects
Whether Britain is able to do that is currently under discussion. The Science and Technology Facilities Council (STFC), which is responsible for the subscription, says it is examining the plans.
Its problem is that it has an £80m hole in its three-year spending plans to 2011.
To manage its way through this shortfall, the STFC has announced its intention to close certain programmes and cut research grants. Science societies and union officials say the damage to UK physics will be incalculable and will lead to hundreds of job losses (including at the Daresbury Laboratory, which is home to the UK's own pioneering Synchrotron Radiation Source).
But the STFC is not alone in having money problems. The Germans will lead the development of Europe's next-generation "light source" - the X-ray Free-Electron Laser (XFEL). This facility should make it possible, for example, to film the very moment a chemical reaction occurs.
But this billion-euro (£750m) project will sap German resources just as the ESRF is looking for its extra funds.
"The partners have accepted the reinvestment programme but they are trying to work out their financing," said Professor Stirling. "If this isn't available, we would try to reschedule the programme and maybe spread it over a slightly longer time. However, if the programme doesn't go ahead I think the effect for European science and for Europeanization in general will be very sad."
The 200m-euro ESRF upgrade will improve the resolution and stability of the Grenoble X-ray beams, and allow researchers to study how materials behave under extreme conditions, of high temperature, pressure and magnetisation.
The upgrade would take ESRF into new areas of science, Professor Stirling said.
"For one of the most important and exciting areas of current science - that is nanoscience, nanotechnology - we are aiming to provide X-ray beams which are very much smaller than the current ones available," he told BBC News.
EUROPEAN LIGHT SOURCE
Electrons are fired into a linac, or straight accelerator. They're boosted in a small ring before entering the storage ring. The superfast particles are corralled by a train of magnets. Energy lost by turning electrons emerges as intense light (X-rays).
The 850m-circumference ring has 32 magnet clusters, or cells. Electrons turned by plain magnets produce 'standard' X-rays. Particles 'wiggled' at undulator magnets emit stronger X-rays. X- rays can't turn with electrons and head straight down beamlines.
Experiment 'hutches' receive the most intense X-rays in Europe. The light probes materials on the atomic and molecular scale. Robots can place many samples in the beam for rapid science. ESRF data leads to new materials, drugs, electronics, etc.
"That is, down to even 10 nanometres (billionths of a metre). With that you will be able to see single elements within an electronic array. We'll be able to look at very small groups of atoms placed on a surface; we'll be able to look at a very small group of molecules.
"We believe this is the way a lot of science is going and we want to be able to provide the tools for European and UK scientists to do this work."
Professor Stirling was speaking in London where he is to receive the Glazebrook Medal from the Institute of Physics - an award that recognises his "outstanding leadership in managing and taking forward a world-leading laboratory, and his innovative work in neutron and X-ray scattering science".
The UK recently opened the Diamond Light Source, a ring that operates at slightly lower energies than ESRF.