Rushed decision on collider would limit useful options

Sir

Your Editorial about the International Linear Collider (ILC), “Making collider endorsement count” (Nature 440, 1089; 200610.1038/4401089a), states that CERN has insisted “that decisions about the siting of the ILC be delayed until an accelerator technology it is trying to develop is ready”. This is untrue.

CERN's position is that no irreversible decision on building a linear collider should be taken until the end of the decade. By that time, the Large Hadron Collider — the particle-physics community's current flagship facility — will have produced its first results, a full technical design for the ILC will be ready, and we will know whether the technology for a more powerful compact linear collider (CLIC) is feasible. These ingredients will allow the global particle-physics community to take an informed and responsible decision on its future. Moreover, funding is simply not available on a shorter timescale for such a huge project to begin.

You report that some in the community find CERN's position “self-serving”. Yet this is by definition not possible, given that it implements the decisions taken by its 20 member states. The organization's position on the ILC is necessary to ensure the optimum use of public resources in this exciting area of research. Contrary to the implication in your Editorial, CERN has accelerated research and development on CLIC precisely so as not to delay the decision on the ILC.

Also contrary to the implication in your Editorial, CERN contributes to the ILC by providing personnel and material resources, and by participating in European networks for ILC research and development.