In 1992 the Rutherford Appleton Laboratory and the Forschungszentrum Jülich started developing and designing a MW spallation neutron source, after a report for the European Commission had identified such a neutron source as one of the major new scientific infrastructural priorities for Europe. In 1997 by then some 10 labs and universities published the first design. The science case that was published at the same time was a joint publication of the ESS project and the European Science Foundation. The partners decided to start an R&D phase to investigate the technical challenges that had been identified. This phase was to last until mid 2000, and was followed by the Project Proposal Phase that was completed by the official European presentation of the science case and the design of the ESS facility with its 5 MW short pulse and 5 MW long pulse target stations. Also in Bonn five sites presented their ambition to host the ESS, most of them consortia involving regional governments. In the meantime, the partners from all over Europe had agreed to conclude a formal MoU with three major objectives:

1. To complete the proposal and formally present it, which happened in Bonn in May 2002;

2. To continue with a Baseline Design Phase that should result in a baseline engineering design by the end of 2003;

3. To get a political decision to construct the ESS late 2003/early 2004.

The time schedule was determined by the ambition to maintain without interruption Europe’s lead in neutron science by providing the world’s best facility. As a matter of fact much political and planning work had been carried out in previous years. In the mid nineties the UK instigated and provided chair and secretary of the OECD Megascience Forum Working Party that developed the global strategy for neutrons that was eventually endorsed by OECD ministers in 1999. One of its main elements was that the USA, Japan and Europe all needed a MW class spallation source. When the USA and Japan started construction of their MW spallation sources, in 1999 and 2000 respectively, it became clear that Europe would have a hard time to fulfil the ambition for continued leadership in the long run. Given the complexity of European decision making on large facilities a decision earlier than 2003/2004 did not appear to be realistic, as informal governmental consultations pointed out. However, as ESF’s Secretary-General Enric Banda underlined in May 2002 in Bonn, a call upon governments to decide to build ESS in the timeframe indicated, seemed wholly appropriate. It was not to be.

The EU member states have established in April 2002 on the initiative of the European Commission a European Strategy Forum on Research Infrastructures (ESFRI) for consultation among governments on the need and the planning for new infrastructures for research in Europe. Its first case was the field of neutrons. A special Working Group was formed to analyse various scenarios for the top tier neutron facility in Europe. Benchmarking performance against a 1.4 MW SNS (to be operational in 2006) it concluded in its report of December 2002 that ESS would give Europe a lead in all relevant scientific fields, a staged approach with a long pulse 5 MW target station first would still give a lead in several fields, while a 1MW short pulse option (either by upgrading ISIS or as a green field AUSTRON version) would keep Europe competitive. If, as now seems likely, SNS would swiftly be upgraded to e.g. 2.5 MW, the Working Group noted that the competitive position of the various options would of course change.

The ESFRI Forum concluded, however, that there was no readiness among governments to decide now on a new source. The baseline scenario, which rests on ILL including its Millennium refurbishment programme and on ISIS with a second target station, will be the European road for the next period. There was an explicit conclusion that Europe needs a major new spallation source in the long run, but no timing for a decision was specified.

Ongoing discussions in a number of countries have confirmed that a decision within the desired timeframe is impossible. On that basis the Council of the ESS Project has decided to discontinue the MoU as of 1 September 2003 and to disband the Central Project Team in Jülich. While the first objective of the MoU has been fully met, the Council judged a continuation of the detailed engineering and costing work no longer relevant in the face of an unspecified delay and the impossibility of achieving the third objective, that is a decision in 2003/2004. Similarly, no use will now be made of the readiness of the German Science Council to re-evaluate ESS and the agreement between the German partners and regional governments and the Science Council to do so in a two-step procedure.

Conclusion

So here is the European situation. The ESS project has been fully designed, apart from detailed engineering and costing in a number of areas. As the ESFRI analysis has shown, it exhausts the possible options for a next European Spallation Neutron Source, apart from the 1 MW short pulse options, and of course apart from decisions on the final power level and subsequent optimisations. Scientifically it looks doubtful, however, to have a 1 MW European top facility 10 years after the Americans and the Japanese have about or more than 1 MW, and maybe 5 years after the SNS could operate in a user mode at 2.5 MW.

The science case will be continually updated: in collaboration with SNS and J-PARC efforts will be mounted to broaden the case to new prospective communities. Technical capabilities at the main “ESS” laboratories will be maintained, if FP6 applications will be successful. At least one and, hopefully two European instruments at SNS will enable European labs to gain experience in developing and operating instruments at a MW source. The status and documentation of the ESS work is such that a 2-year period of baselining and construction planning before a formal decision allows to pick up again the 8-year construction planning for ESS or any future MW spallation source. Prototyping need not start until shortly after the beginning of this 2-year period, and may be postponed further at a price of slightly higher risks and cost uncertainties.


A simple organisation will be set up to instigate and co-ordinate the necessary activities on the part of the scientists and the labs involved, and to act as the interlocutor for policy responsibles. As a last recommendation the ESS Council members have expressed the hope that it could be based at ILL.

A new website (www.neutron-eu.net) is available to continue information provision on ESS, on new activities, as well as to cover the NMI3, ENSA, and the International Society Muon Spectroscopy Europe.

What remains is a tentative detailed time schedule. Could it be as follows?

To maintain the UK’s outstanding position in neutron research, the UK government has committed itself to evaluate plans for a future top tier spallation facility, including ESS, with a view to eventually prepare a bid for the so-called UK Spending Review 2006. That implies that a UK judgement will essentially be available mid 2005. The UK government has, too, committed itself to consultations with its European partners to arrive at a common view as to what is desirable and feasible. This process will start with a meeting in the autumn of 2003.

If the next 2 years until mid 2005 are used for consultations, evaluations, broadening the science case and getting consensus on the scoping of the new facility on the basis of the further updated science case and informed views on what is realistic, a decision to start the 20 M€ 2-year baselining and construction planning could be taken late 2005. A decision to start prototyping, also estimated to cost 20 M€, can be taken any time afterwards. In this way a final decision to build the new facility is due for late 2007, which implies that major budgetary impacts begin to be felt in 2009/2010. (Schedule for the realisation of a new MW spallation source)

Europe, and the ambitions it nourishes, deserve that all actors concerned try to agree on such a time schedule.


Peter Tindemans
Former Chairman, ESS Council