The European Spallation Source, 15 years in the making

1. The European Spallation Source, 15 years in the making Dr Peter Tindemans chair ESS Preparatory Phase Board NuPECC, Glasgow, 4 October 2008 Glasgow, 4 October 2008 - Peter Tindemans

2. Overview • High-end neutron sources in Europe; top tier sources world-wide 10 years after OECD Megascience Forum’s Global Neutron Strategy • The current choice for Europe’s future top tier facility and its expected performance • Science • Technology • Current situation: three bids to host ESS; ESFRI Site Review Panel Glasgow, 4 October- Peter Tindemans

3. 1) refurbish some national ones; 2) maximise potential of ILL and ISIS; 3) three MW class in E, US, J (Asia-Pacific) OECD: A three-pronged global strategy Poznan, 9 May 2008 - Peter Tindemans

4. High-end and top tier sources • ILL reactor and ISIS spallation source were for a long time world’s best facilities; FRM-II reactor in Munich of ILL class • ESS Starting seriously early 90-ties: FZ Jülich, RAL • USA: ANS (Advanced Neutron Source) high power, high density reactor, abandoned ’96/’97 for Spallation Source SNS, utilising ESS design • J-PARC: proton accelerator research complex, incorporating JSNS with similar target design as ESS: liquid Hg Glasgow, 4 October 2008 - Peter Tindemans

5. A brief history of ESS Cooperating labs • 1992, 1993 FZJülich and RAL start technical work ESS (R&D) Council in charge (~1995 – 2003) • 1997 First science case and first technical design: further R&D areas identified • 1997 – 2002 More R&D, more detailed technical design • 2000 – 2001 Investigation of multipurpose linac project CONCERT: 25 MW linac for neutrons, transmutation, nuclear physics, … CEA discontinued • May 2002, Official presentation of ESS project to governments and the science community in Bonn, 5 interested sites • 2003 Governments: Europe needs ESS, but at a later stage • Technical team and ESS Council discontinued ESS Initiative: ENSA, sites and major labs; hosted at ILL (2004 – 2007) • 2005 choice for ESS with one, 5 MW Long Pulse target station • 2006 ESS on ESFRI Road Map • 2004 – 2007: three countries officially committed to be site candidate ESS Preparatory Phase Board (2007 onwards) Glasgow. 4 October 2008 - Peter Tindemans

6. The ESS to be built Arguments • SNS + 10 (+) years ESS “5x SNS” in many areas • Maintain network of sources • Cost-effectiveness dictates: eventually as many instruments as possible • Start in as complementary a mode as possible Choice • start with 5 MW LP with: • 20, and eventually maybe 35 - 40 instruments • As many ancillary and science facilities as affordable • Ready to operate in ‘industry-mode’ too: access mode (financial, time), IP arrangements, demonstration experiments, standardised procedures, etc.) and as much as possible upgradeable to: • More power • More target stations (SP, LP, low power dedicated TSs Costs • ~1.3 B€2008 investment; 110 M€2008 /y operating. Glasgow,. 4 October 2008 - Peter Tindemans

7. Glasgow, 4 October 2008 - Peter Tindemans

8. The science: which ESS? Pulse length requirements Pulse length requirements by scientific needs:  Irradiation work:  Single (Q,) experiments (D3, TAS?):   SANS, NSE: 2 – 4 ms Reflectometry: 0.5 – 2 ms  Single Xtal diffraction: 100 – 500 s Powder diffraction: 5 – 500 s Cold neutron spectroscopy: 50 – 2000 s Thermal neutron spectroscopy: 20 – 600 s  Hot neutron spectroscopy: 10 – 300 s  Electronvolt spectroscopy: 1 – 10 s Backscattering spectroscopy: 10 – 100 s, … Long pulse sources don’t loose intensity when there is no need for excessive resolution, so peak flux characterizes source performance for sufficiently long pulses. Shaping of ms long pulses feasible for > 95 % of cases Hence: high power LP source with optimised instruments is way forward Courtesy Feri Mezei Glasgow, 4 October 2008 - Peter Tindemans

9. Pulses for High-Intensity TOF Reflectometer; various sources Ratio of areas defines relative power: 1:13:110:3; (only pulse duration is shown) Glasgow, 4 October 2008 - Peter Tindemans

10. Figures of merit ESS LPTS advantages: Higher cold peak flux More often „sufficient“ pulse length Adjustable resolution Cleaner line shape Glasgow, 4 October 2008 - Peter Tindemans

11. Comparing 3 European scenarios to SNS Glasgow, 4 October 2008 - Peter Tindemans

12. 2003 Design of 10 MW ESS • 5 MW SP and a 5 MW LP target station • H- Ion sources • Compressor ring to produce very short (~ 1μs) pulses Glasgow, 4 October 2008 - Peter Tindemans

13. Technology: a mature accelerator • Ion source for 5 MW LP: exists • Linac: SNS commissioned 08-05: beyond specs; others as well • No compression ring Glasgow, 4 October 2008 - Peter Tindemans

14. Accelerator Design Review and Optimisation • Design of ESS accelerator was completed in 2002-03, and at that moment considered the best mix between NC technology and SC technology. • Many relevant developments; several linac projects ongoing; SNS completed. • Completion of baseline engineering, including modifications to optimise cost-performance ratio, were always assumed to take up to 2 years and cost ~ 30M€. • Obvious areas for consideration in design review: • SC cavities below 400 MeV? How low? • Higher gradients per cavity, but high beam current poses limitations • Is one H+ ion source possible? Is it desirable to avoid funnel (front end intensity limited)? One source and 2 GeV? • Frequencies: CERN or DESY frequencies? Yet components will differ due to high beam current, long pulses and low rep rate, necessary for optimal neutron production • Be careful about beam quality, impact on upgradeability, costs, etc. Glasgow, 4 October 2008 - Peter Tindemans

15. Target Hg – Mercury 1 m3 Neutron Beam protons Neutron Beam Neutron beam Moderator Moderator Poznan, 9 May 2008 - Peter Tindemans

16. 5 MW LP target perfectly feasible • Target challenges: engineering, radiation, pitting (from shock waves) • SNS shows: engineering of liquid Hg target is feasible • Radiation damage to container is limited (LAMPF beam dump, PSI’s liquid PbBi target accumulated as much irradiation as months operation of ESS target; SNS target does extremely well) • What about pitting? SP targets above 2 MW or so seriously affected. There may be solutions (e.g. injecting He bubbles) but 5 MW SP target was too optimistic, at least poses serious risks • Appreciate radical difference between SP and LP target • SP: 23 kJ proton pulse deposited in 1 μs ~ 20 GW instantaneous power (20 x Niagara Falls!) • LP: 300 kJ proton pulse deposited in 2 ms ~ 150 MW (same as HFIR) Glasgow, 4 October 2008 - Peter Tindemans

17. For LP target station pitting no big problem Nature of pitting problem • Almost all proton pulse energy deposited as heat in target Temperature jump of irradiated volume Pressure jump, as heat has to be absorbed in constant volume (inertia of Hg doesn’t allow fast thermal expansion) Pressure jump travels as shock wave at velocity of sound and bounces between walls Cavitation damage (pitting). • However, propagation of sound waves allows expansion of liquid Hg and release pressure: in ~ 30 μs expansion will reach adjacent volume (outside the 2 liter irradiated volume). Does this reduce problem? • Compare now SP and LP • SP: total pulse energy 23 kJ in 1 μs (<< 30 μs). No reduction • LP: only ~ 4 kJ in 30 μs (as 300 kJ pulse has 2 ms duration) so full energy distributed over much larger (2 orders magnitude) volume; moreover shock wave only due to the 4 kJ; it travels on top of continuously spreading pressure Glasgow, 4 October 2008 - Peter Tindemans

18. Instrument optimalisation • Source and instrument characteristics need to be tailored to each other for optimal performance • Rencurel workshop *): Monte Carlo simulations on wide range of instruments, using pulse shaping and frame multiplication by using multiple choppers • Additional gains through modern neutron optics • Cold TOF: up to 100x IN5 at ILL under favourable conditions • Back scattering (among least favourable at LP source): still competitive with back scattering at SNS • SANS: considerably higher than any competitor (SP or CW) of equal time averaged flux; and for whole variety of SANS instruments now in use (focusing, magnetic, SESANS, ..) • Single crystal spectrometer: at least competitive • Protein Crystallography Station: shown to be feasible on LP source; will revolutionise applications of neutrons in protein crystallography • Reflectometers: outperforms ILL; competes very favourably with SNS *) H. Schober et al, Nucl. Instr and Methods in Phys. Res., A 589 (2008) 34-46 Glasgow, 4 October 2008 - Peter Tindemans

19. Cost-effective, innovative, feasible Conclusion • Initial configuration is by far the best you can get for the price • Totally mature design: innovative combination of available technologies • Upgradeability warrants ESS will be with further relatively small investments best facility for next 40 years or so. Glasgow, 4 October 2008 - Peter Tindemans

20. Changes in European political landscape brought us to where we are • ESFRI Road Map (modeled after DoE 20-year facilities outlook) + strong desire of countries and European Commission to implement this • ESS and ILL 20/20 are the (only) neutron projects on this Road Map of European projects. • ESS is exactly as proposed by ESS Initiative: 5 MW LP upgradeable, same timeschedule (first neutrons 2017/2018). No need for new science review • UK Neutron Review • Science case unequivocal • Reviewing 1 MW upgrade of ISIS and new multi-MW European source : • ‘next generation European Source’ is first priority. • No feasibility study into ISIS upgrade yet. • Three very serious site candidatures formally proposed by their governments and backed up with money Glasgow, 4 October 2008 - Peter Tindemans

21. ESFRI Road Map 2006 35 ‘infrastructures’: 6 in Social Sciences & Humanities; 7 Environmental Sciences; 3 Energy; 6 Biomedical & Life Sciences; and then: Glasgow, 4 October 2008 - Peter Tindemans

22. Serious site candidates • Scandinavia/Sweden: Lund • Spain/Basque Country: Bilbao • Hungary: Debrecen • Governments pledged each between 300 and 400 M€ for construction (including site premium); innovative schemes (either EIB’s Risk Sharing Financing Facility or - in Spain’s case - National Innovation Fund) to bridge mismatches between financing requirements and flow of contributions. • Larger (initial) share in operational costs than corresponding to current size of neutron communities • All set up project organisations and committed funds in the order of millions of Euros for the next few years. • All meet basic site requirements. • Site contenders have started to inform and negotiate with other governments. Round Table meetings held. • Supplying decentrally constructed components? Yes, but strict central project leadership (ideally full power of the purse): cf. SNS-model Glasgow, 4 October 2008 - Peter Tindemans

23. Towards a decision ESFRI instigated official Site Review December 2007 • Sites responded (end April 2008) to Questionnaire • Site visits and review (July 2008): Catherine Cesarsky (former DG ESO), Thom Mason (director ORNL), Norbert Holtkamp (dep DG ITER), Peter Tindemans. Reported on • Science and design issues • Legal structure and applicable tax regime (esp. VAT) • Cost estimates: any site-dependent aspects? • Financial offers • Physical site characteristics • Licensing issues • Local team, envisioned building up of international team • Living and working conditions • Scientific and industrial environment • ESFRI transmits Review second half October to ministers • Some hope that Council of Ministers and Infrastructure Conference at Versailles in December 2008 will mark next step Glasgow, 4 October 2008 - Peter Tindemans

24. FP7: ESS Preparatory Phase Project Site decision and basic financial agreement parallel to 2-year Preparatory Phase project, (5 M€ EU support) starting April 2008) Issues: Site reviews to get better more comparable site proposals Addressing more in-depth safety issues, socio-economic aspects, regulatory requirements Environmental compliance issues different target materials Radio-active inventory, emission, handling, storage Decommissioning Upgradeability Novel ideas for user operations ,and for governance Enhancing support for ES: industry, funding agencies, public at large, politics Glasgow, 4 October 2008 - Peter Tindemans

25. The Dark Horse’s finish • Editorial Science magazine (October 2006, after ESFRI ROAD Map): “Dark Horse ESS re-enters the race” • A coalition of core countries seems to be in the making • How much time needed? Site Review Group’s view: • 2 years for design review, design optimisation and completion of baseline engineering • 5-6 years for construction until first neutrons • Let us hope Europe lives up to the challenge after 15 years! Glasgow, 4 October 2008 - Peter Tindemans