Sir

On 18 July you reported (Nature 418, 262; 2002) a review of major facilities and an assessment of the European Spallation Source (ESS) by Germany's science council, the Wissenschaftsrat. As your report says: “The council endorsed an assessment of the ESS by a subcommittee ... that the demand for neutrons does not justify the estimated 1.4-billion-euro (US$1.4-billion) total investment in an advanced neutron source.” This assessment reflected neither the consensus view of the subcommittee nor the opinion of most members. As members of this subcommittee, we have written to the chair of the Wissenschaftsrat with our concerns, paraphrased below.

“Contrary to the impression given by the draft subcommittee report presented to the Wissenschaftsrat, most of the committee judged the scientific case for the ESS to be very strong. The research opportunities for many fields of applied and fundamental science, such as solid state physics/chemistry, particle physics, biology and engineering, were seen as novel and outstanding. Critical remarks by some members were confined to the area of polymer physics/chemistry.

“Further, contrary to the summary of our deliberations in the Wissenschaftsrat's report, we do not see reason for concern about the timeliness of the scientific programme. We agree with the Japanese and US research communities, who have successfully sought long-term funding for high-intensity spallation sources, that experiments with neutrons will play a leading role across the sciences for the foreseeable future.

“The Wissenschaftsrat's statement on the cost of neutrons relative to other techniques is not based on input from us and we do not believe it would be supported by a comprehensive analysis.”