1. Date Event Global Design Effort 1 ALCPG Briefing on ILC Cost Reduction Studies Ewan Paterson Personal Views GDE May 15, 08

2. Date Event Global Design Effort 2 Background We are now in a new regime TDP-1 by 2010 and TDP-2 by 2012 Not in a “crash” program towards an EDR by 2010 Limited global resources concentrating on major technical issues…gradient, e-cloud, etc Time to step back and take a hard look at the RDR design and cost. The biggest cost driver is the SCRF technology and the main linac which has the priority. Now look at everything else as resources permit.

3. Date Event Global Design Effort 3 Reducing the COST

4. Date Event Global Design Effort 4 TILC – Working Groups WG-1Cost Reduction Studies APPROACH –Review and evaluate RDR design –Re-visit (Caltech) cost reduction lists –Brainstorming SPECIFIC TARGETS (Cost Drivers) –Staging? / Scope? –Main Linac Technology –CDF -- Scope of halls, caverns, shafts, etc. Two vs One tunnel. Shallow vs Deep sites GOALS –Sendai – establish cost reduction goals (for study) NOTE –NO CHANGES OF PHYSICS SCOPE WITHOUT ENGAGING EXPERIMENTAL COMMUNITY B. Barish

5. Date Event Global Design Effort 5 Some themes from Top-10 lists Civil, siting: –Single tunnel, shallow site,.. –Underground space utilization Accelerator –Positron source –DR short-bunch design, eliminate BC2 Engineering –HLRF: Marx, no circulators,… –Magnet stringing, power supply –Increase cooling water delta-T

6. Date Event Global Design Effort 6 Site Studies (Also a cost-reduction study) Shallow site –Cut and cover + klystron gallery –Shallow tunnel + klystron gallery Single-tunnel (XFEL-like) options –An engineered / construction solution –We get this (almost) for free. Focus of JINR (Dubna) GDE Meeting (06.08) –JINR shallow-site studies –CERN (CLIC-ILC) collaboration Formally part of ILC- HIGRADE (European) programme

7. Date Event Global Design Effort 7 Steps since Sendai Formation of a Cost Management Group Program Mgrs and Assistants Cost Engineers Himel, Elsen and Paterson Plan Dubna meeting. Emphasis is CF&S designs and costs Dubna site, example of shallow site Follow on to some Sendai discussions

8. Date Event Global Design Effort 8 Partial Dubna Schedule

9. Date Event Global Design Effort 9 Staging and Some Possible Design Changes Ewan Paterson GDE

10. Date Event Global Design Effort 10 What is Staging? There is a very large range of opinions. Here are two extremes e.g. All spares or backup equipment moves to operations or Start with 2 low emittance, polarized guns (not yet developed), no DR’s, 2 linacs of 150GeV in different layout. (DIFFERENT MACHINE) I will not consider either extreme but we do need a working definition.

11. Date Event Global Design Effort 11 My Definition Staged energy, luminosity or related parameters on an e+/e- machine which is a subset of the base design and there is a clear upgrade path. AND The upgrade path to the base machine or beyond must be realistic in terms of time down for physics?? Not years Still rather vague!

12. Date Event Global Design Effort 12 Staging Energy This is part of design philosophy (beyond 500 GeV ) but we have to be clearer as to what is IN and OUT of design and costs. When we consider Energy staging should we take an example of 300-500->?? GeV with continuing construction of components and maybe CF&S. This approach is the best match to a new International Facility that has stable yearly funding, like CERN, which bridges construction, operations and upgrades. (A DREAM)

13. Date Event Global Design Effort 13 Staging Energy Issues The most “attractive” approach to energy staging is to do everything in the center and expand outwards. BUT there are issues The turnaround, ….what does it cost to duplicate? Compressor(s)…..Could we compress before transport and turn? Where is the E+ source? Can we standardize linac quads (presently there are 3 strengths in every third cryostat) to operate over a larger range? Construction and installation during operation?

14. Date Event Global Design Effort 14 Staging the present CDR design Build the CDR CF&S Install only first ½ linacs after the compressors with E+ source at midpoint Install second half of linacs during downtimes of first 2 to 3 years of operation. Continue civil construction outwards?? If questions on previous slide get positive answers then one would re-optimize this scenario. There are many other options with only ½ the power sources and cryostats that have to be looked at, but my opinion is they cost more!

15. Date Event Global Design Effort 15 Summary of Staging There will be many ideas on staging and design changes like this, that will surface at Dubna. We want creativity. The only decisions made at Dubna will be to identify the ideas that justify further study. Now look at examples of accelerator design changes towards reduced cost.

16. Date Event Global Design Effort 16 Accelerator Design Change Ideas Assumption:- Reduce the footprint of any design lowers the “capital” cost”. These ideas would work with 1 or 2 tunnels, shallow or deep but the cost differentials would change. In the central region the different elevations of the Injectors and DR’s enabled operation of these facilities with open access to the BDS, the IR and linacs. Let us assume that with tunnel shielding walls and creativity we can do the same but with larger “no access” zones.

17. Date Event Global Design Effort 17 Accelerator Design Changes (1) Lower DR to plane of BDS crossing the BDS ~1 km from the IR. Some gates and shielding walls (muon shield exists) will allow access to IR and linac…………..remove escalators on both sides….> 1km of tunnel and beamlines. The e+ layout has > 400m of drift to allow the photon beam to expand before it drills through the target. This is true regardless of whether one uses a chicane or dogleg. With imagination and enough transverse space, we could include in this drift an e- injector whose beam could hit the same e+ target, or modified version. This would be a form of auxiliary or “KAS” with 1 to 2% intensity and keep everyone happy!

18. Date Event Global Design Effort 18 RDR KAS + BOOSTER

19. Date Event Global Design Effort 19 Accelerator Design Changes (2) The BDS has a mixed density of components and has offsets like the e+ source! If we fixed the maximum energy that is required of the BDS so that the lattice is known then in principle we have enough Z space to have the E+ source, the keep alive and the 5 GeV boosters between the end of the linac and the DR with 1 km left to the IR!! In a one or two tunnel design this saves a lot of tunnel (which may have to be larger diameter) and the 1 km positron insert. This needs work from several technical areas and cost experts

20. Date Event Global Design Effort 20 Positron Sources Options Ewan Paterson GDE

21. Date Event Global Design Effort 21 RDR E+ SOURCES (Undulator) The RDR E+ source is based on an Helical Undulator design at 150 GeV (~10MeV photons on tgt) which meets design goals for intensity and produces ~30% polarized beam. E+/- timing not addressed! A Keep Alive Source (conventional e- on tgt) produces ~10% e+ current and is situated near the DR Best update on technical issues with this design, the R&D programs and open questions, can be found at the ILC Positron Collaboration Meeting (07-09 April 2008). See “http://ilcagenda.linearcollider.org/conferenceTimeTa ble.py?confId=2639&showDate=all&showSession=all &detailLevel=contribution&viewMode=session”

22. Date Event Global Design Effort 22 Continued Some questions that are not yet adequately addressed or require decisions are :- Timing e+/- issues Fast spin control Accurate polarization measurement Layout of components and e- drive source beam, chicane, dogleg etc Location, and therefore drive beam energy, along e- linac

23. Date Event Global Design Effort 23 The Keep Alive Source Candidate for deletion----impact is on commissioning and availability. Would be unnecessary if one chose conventional e+ source. It is a 1/10 power conventional source with the similar power level target/capture section as undulator source. Revisit the intensity required. Can be used for Z-Calib running. If deleted one should shorten the tunnels on BOTH sides by ~200 m,..see next slide

24. Date Event Global Design Effort 24 RDR KAS + BOOSTER

25. Date Event Global Design Effort 25 Conventional E+ Source Could be alternative to Undulator source Would have zero polarization Less costly…….how much? No timing problems Replaces KAS, use for Z-calib, GigaZ and E-E- running. BUT More R&D required on high power on thick target (see KAS comment). Increased costs in target capture section…is this properly accounted in comparison? Upgrade path to 60% polarized beam (if required) still unclear involves backscattered laser system or Undulator scheme.

26. Date Event Global Design Effort 26 Undulator E+ Source Systems Undulator Need ~ 100 m of undulator to cover all operating range of ILC….probably modular. Helical undulator is practical and easily gives 30% polarization from total source Planar undulator is probably cheaper but how much? Certainly not XFEL or LCLS style! Whether undulator has a chicane, dogleg or other geometry, the ‘drift’ to target from the end of undulator must be > 400 m ! Growing consensus that undulator offset could be ~ 1 m and not 2.5 m. Tunnel diameter?

27. Date Event Global Design Effort 27 Undulator E+ Source Systems Target, capture, accelerator systems Continuing R&D on these systems indicate “No show stoppers” J Clarke, I agree! Optimization or ‘Standardization' of warm and cold accelerator systems for e+ source, KAS and e- source should be done but after decisions are made on their survival. The same is true for the 5 GeV booster linacs prior to the DR’s. Standardization of these systems may not be cost effective as aperture requirements (beam emittances) are quite different.

28. Date Event Global Design Effort 28 Location of Undulator Source To first order having this source at the 150 GeV point or the end of the linac does not change the costs? (simple translation) Drive beam is twice as rigid so manipulation takes more Z space! It does impact on staging scenarios for operating energy and it does impact the tuning and operation of the source systems. It does open up consideration of alternate layouts, some ideas old some new. The study of these is work in progress.

29. Date Event Global Design Effort 29 SUMMARY Before making decisions on changes to the RDR base design we need R&D on…. High power e- an target designs. More discussions on the relative value of e+ polarization and low energy running during the first years of operation. AND A relative short term evaluation (Dubna?) of the possibilities by sources, BDS, operations and civil experts, as whether there is a combination of the design requirements that can be achieved in a design where they share the same tunnel length and space.