Glasgow, 4 October Peter Tindemans1 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- Peter Tindemans2 Overview 1.High-end neutron sources in Europe; top tier sources world-wide 10 years after OECD Megascience Forums Global Neutron Strategy 2.The current choice for Europes future top tier facility and its expected performance Science Technology 3.Current situation: three bids to host ESS; ESFRI Site Review Panel

Poznan, 9 May Peter Tindemans3 OECD: A three-pronged global strategy 1) refurbish some national ones; 2) maximise potential of ILL and ISIS; 3) three MW class in E, US, J (Asia-Pacific)

Glasgow, 4 October Peter Tindemans4 High-end and top tier sources ILL reactor and ISIS spallation source were for a long time worlds 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

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 Peter Tindemans5

Glasgow,. 4 October Peter Tindemans6 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 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.

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8 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 dont 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 The science: which ESS? Pulse length requirements Courtesy Feri Mezei

Glasgow, 4 October Peter Tindemans9 Ratio of areas defines relative power: 1:13:110:3; (only pulse duration is shown) Pulses for High-Intensity TOF Reflectometer; various sources

Glasgow, 4 October Peter Tindemans10 ESS LPTS advantages: Higher cold peak flux More often sufficient pulse length Adjustable resolution Cleaner line shape Figures of merit

Glasgow, 4 October Peter Tindemans11 Important Contribution to European Priority Research Mission Flagship Field of Research Scenario 1 ESS Scenario 2 5 MW Long Pulse Scenario 3 a 1 MW Short Pulse 10 Hz Scenario 3 b 1 MW Short Pulse 50 Hz Functional Materials, Microsystems and IT, Nanotechnology. Solid State Physics WLSLCC Microsystems and IT, Functional Materials, Nanotechnologies, Traffic and Transport, Sustainable Development. Material Science & Engineering WLSLCC Functional Materials, Nanotechnologies, Traffic and Transport, Sustainable Development Liquids &Glasses WLSLCC Functional Materials, Nanotechnologies, Traffic and Transport, Sustainable Development Soft Condensed Matter WL SLC Functional Material, Health, Sustainable Development Chemical Structure Kinetics & Dynamics WLSLCC Health and Biotechnology Biology & Biotechnology WL CC Traffic and Transport, Cultural Heritage, Sustainable Development Mineral Science, Earth Science, Environment and Cultural Heritage WLSLCC Cosmology, Origin of the Universe, Education, Public Understanding Fundamental Physics WL SLC Comparing 3 European scenarios to SNS

Glasgow, 4 October Peter Tindemans12 5 MW SP and a 5 MW LP target station H - Ion sources Compressor ring to produce very short (~ 1μs) pulses 2003 Design of 10 MW ESS

Glasgow, 4 October Peter Tindemans13 Ion source for 5 MW LP: exists Linac: SNS commissioned 08-05: beyond specs; others as well No compression ring Technology: a mature accelerator

Accelerator Design Review and Optimisation Design of ESS accelerator was completed in , 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 Peter Tindemans14

Poznan, 9 May Peter Tindemans15 protons Hg – Mercury 1 m 3 Neutron Beam Neutron Beam Neutron beam Moderator Target

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, PSIs 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 Peter Tindemans16

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 doesnt 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 Peter Tindemans17

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) Glasgow, 4 October Peter Tindemans18

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 Peter Tindemans19

Glasgow, 4 October Peter Tindemans20 Changes in European political landscape brought us to where we are 1.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 2.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. 3.Three very serious site candidatures formally proposed by their governments and backed up with money

Glasgow, 4 October Peter Tindemans21 ESFRI Road Map infrastructures: 6 in Social Sciences & Humanities; 7 Environmental Sciences; 3 Energy; 6 Biomedical & Life Sciences; and then:

Glasgow, 4 October Peter Tindemans22 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 EIBs Risk Sharing Financing Facility or - in Spains 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 Peter Tindemans23 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 Peter Tindemans24 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

The Dark Horses 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 Groups 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 Peter Tindemans25