High-end neutron sources in Europe; top tier sources world-wide 10 years after oecd megascience Forum’s Global Neutron Strategy

High-end neutron sources in Europe; top tier sources world-wide 10 years after OECD Megascience Forum’s Global Neutron Strategy

• 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

ILL reactor and ISIS spallation source were for a long time world’s best facilities; FRM-II reactor in Munich of ILL class

• 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

Cooperating labs

• 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)

Arguments

• 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.

Design of ESS accelerator was completed in 2002-03, and at that moment considered the best mix between NC technology and SC technology.

• 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.

Target challenges: engineering, radiation, pitting (from shock waves)

• 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)

Nature of pitting 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

Source and instrument characteristics need to be tailored to each other for optimal performance

• 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

Conclusion

• 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.

ESFRI Road Map (modeled after DoE 20-year facilities outlook) + strong desire of countries and European Commission to implement this

• 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

Scandinavia/Sweden: Lund

• 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

ESFRI instigated official Site Review December 2007

• 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

Editorial Science magazine (October 2006, after ESFRI ROAD Map): “Dark Horse ESS re-enters the race”

• 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!