Sir

I would like to comment on two points arising from your Opinion article and News story on the TESLA project (Nature 410; 395; 2001) & (Nature 410; 397; 2001).

First, the cost of 3,136 million euros (US$2,811 million) for the TESLA 500-GeV electron–positron linear collider is based on experience of construction of a complete test facility, on operation for four years, and on a full costing performed by industry, including the effects of mass production.

I disagree with your opinion that the cost will double when labour and operation costs are included, because all components will be fabricated by industry and the associated labour costs are included in the price. Testing and assembly of components will require roughly 7,000 person-years, the cost of which will have to be added to the investment cost, and which amounts to no more than 10–20% of the total cost, depending on national salary scales. Operating costs are not included in any of the existing cost estimates: for TESLA these should be 120 million euros a year, or 3% of the investment.

Second, you state in your editorial on the German, US and Japanese plans for linear accelerators that Europeans should accept that they have had their turn with CERN's Large Hadron Collider. Your News story says that TESLA in Germany “could mark the virtual eclipse of particle physics in the United States and Japan for a generation”. In my view, regional balance is good but not vital for a field. This has been demonstrated successfully by astronomers who go where the sky tells them, without endangering national programmes.

In particle physics we need a new model of international collaboration to be able to build and operate accelerators as global endeavours, in which all partners have shares and a say, thus making a facility for all countries, independent of the location. It is important that particle physicists everywhere get behind one common project, and convince their governments to fund and build it wherever the strongest political support is found.