1. Global Design Effort 1 Summary of Technical and Collaboration Related Issues for the ILC Damping Rings N. Walker (for the Project Managers) INFN Frascati 22 January 2009 22.01.2008 - INFN LNF

2. INFN and Damping Rings TESLA TDR –Full cost estimate of TESLA dogbone DR (Ansaldo) EUROTeV (FP6) Programme –WP 3 Damping Rings Coordination: S. Guiducci GDE ILC RDR –DR Area System European coordinator: S. Guiducci (A. Wolski, J. Gao) Continued support & collaboration –DA  NE, SuperB,… Global Design Effort 2001 2007 TDR 2012 22.01.2008 - INFN LNF 2

3. Technical Design Phase Project Three Project Managers –Yamamoto (SCRF) –Ross (CFS/Global) –Walker (AS) Accelerator Systems (AS) responsible for accelerator physics design –Damping Ring is one Technical Area Group in AS –(TAG leader: A. Wolski) Global Design Effort 3 22.01.2008 - INFN LNF

4. Technical Design Phase Project DR TAG work-package structure reflects TD phase 1 focus on Beam Test Facilities –CesrTA (e-cloud) –ATF (emittance, kickers,…) –DA  NE (e-cloud, kickers,…) Others: e.g. KEK-B Two additional WPs for ILC DR design work / costing –Lattice Design –Technical Systems Global Design Effort 22.01.2008 - INFN LNF 4

5. DR & BDS Beam Test Facilities  KEK, Japan  Cornell  INFN Frascati CesrTA (Cornell) electron cloud low emittance DA  NE (INFN Frascati) kicker development electron cloud ATF & ATF2 (KEK) ultra-low emittance Final Focus optics 22.01.2008 - INFN LNF 5 Global Design Effort

6. GDE ILC TD Phase R&D Plan Damping Ring: stated critical R&D: –Demonstration of electron cloud mitigation effects (CesrTA programme, 2010) –Demonstration of ultra-low emittance (KEK ATF, 2009) –Development of 5 ns rise-time injection and extraction kickers (DA  NE experiments, 2010) Damping Ring: Cost – performance studies –2009: within “Minimum Machine” study –Specifically 3km ring option as part of “low-power” option –Other “VALUE ENGINEERING” activities Vacuum system design Power supply solution / layout etc. 22.01.2008 - INFN LNF Global Design Effort 6

7. The ILC Damping Rings 22.01.2008 - INFN LNF Global Design Effort 7 Energy5 GeV Number of bunches: 2625 Charge per bunch:3.2 nC Circumference:6.695 km  t b 6 ns Average current0.4 A Emittances: –Horizontal (equilibrium)5  m –Vertical (extracted)2 pm Damping time25 ms Injection emittance (e+)0.09 m(A x +A y )

8. The ILC Damping Rings Energy5 GeV Number of bunches: 2625 Charge per bunch:3.2 nC Circumference:6.695 km  t b 6 ns  fast kickers Average current0.4 A  instabilities (e-cloud) Emittances: –Horizontal (equilibrium)5  m –Vertical (extracted)2 pm  beyond SotA Damping time25 ms Injection emittance (e+)0.09 m(A x +A y ) 22.01.2008 - INFN LNF Global Design Effort 8

9. RDR Lattice (History) 6.7km TME 22.01.2008 - INFN LNF 9 Global Design Effort

10. Working Lattice (as of TILC08, March 08) 6.7 km ring  z = 9mm  6mm (better for bunch compressor) 22.01.2008 - INFN LNF 10

11. Priority ILC DR R&D (risk mitigating) Electron Cloud –Characterise e-cloud build-up –Development of e-cloud suppression techniques –Develop modelling tools –… Demonstration of <2 pm vertical emittance –Development of low-emittance tuning techniques –Instrumentation –Alignment –… Fast injection / extraction kickers –Fast pulser technology <5ns rise time, 10 -4 stability –Reliability / availability Other –Classical impedance-driven instabilities –Fast-ion instability –… Global Design Effort 22.01.2008 - INFN LNF 11

12. Priority ILC DR R&D (risk mitigating) Electron Cloud –Characterise e-cloud build-up –Development of e-cloud suppression techniques –Develop modelling tools –… Demonstration of <2 pm vertical emittance –Development of low-emittance tuning techniques –Instrumentation –Alignment –… Fast injection / extraction kickers –Fast pulser technology <5ns rise time, 10 -4 stability –Reliability / availability Other –Classical impedance-driven instabilities –Fast-ion instability –… Global Design Effort TD Phase priority TD Phase priority TD Phase priority TD Phase priority TD Phase priority TD Phase priority 22.01.2008 - INFN LNF 12

13. Program Outline 22.01.2008 - INFN LNF Global Design Effort 13 Minimum Machine Technical Design, and Costing Critical R&D 2008Specify tasks.Specify scope. Continue critical R&D for cost reduction and risk mitigation: electron cloud; fast kickers; low-emittance tuning. 2009Perform studies. Perform technical design and costing work in support of revising the baseline configuration. Start 2010 Revise baseline configuration. 2010 – 2012 Complete work for TDR (end 2012). Complete critical R&D. TDP Phase I TDP Phase II

14. Electron Cloud: Goals 1.Collect data to validate the simulation codes in the parameter regime of the ILC damping rings. –We need to understand, and be able to predict, build-up of the cloud under a variety of conditions. –We need to understand, and be able to predict, beam dynamics with e-cloud in ultra-low emittance regime. 2.Develop effective mitigation techniques. –Mitigation methods needed for drifts, dipoles, wigglers. –Methods must be demonstrated and adverse consequences understood. 22.01.2008 - INFN LNF Global Design Effort 14

15. Critical R&D: Electron Cloud 22.01.2008 - INFN LNF Global Design Effort 15 CesrTA KEKB DA  NE E-Cloud Collaboration: ANL Cornell FNAL INFN/LNF KEK LBNL SLAC

16. E-Cloud Studies at DA  NE Multibunch instability caused by electron cloud. Simulations consistent with main observations. 22.01.2008 - INFN LNF Global Design Effort 16 60 equispaced bunches Beam current 1.2 A Growth time ~ 100 turn

17. Fast Kicker R&D The goal is to develop and demonstrate a high- reliability fast kicker that meets the ILC specifications for damping ring injection and extraction. R&D program includes activities at SLAC, INFN/LNF and KEK. 22.01.2008 - INFN LNF Global Design Effort 17 Pulse amplitude10 kV Bunch spacing3 ns Pulse repetition rate6.6 MHz Pulse stability~ 0.1%

18. Fast Injection/Extraction Kickers: LNF Fast, high-power pulsers approaching ILC DR specifications are being tested as part of DA  NE upgrade program. 22.01.2008 - INFN LNF Global Design Effort 18 45 kV 5 ns pulse (FID) DA  NE stripline kicker designs are being modified for devices to be installed for testing in ATF.

19. Low-Emittance Tuning ILC damping rings are specified to operate with 2 pm vertical emittance. Swiss Light Source has recently achieved 3 pm. Low-emittance tuning program includes work at: –ATF: studies of fast ion instability, and demonstration for ILC damping rings (also critical for ATF-2); –CesrTA: motivated by studies of electron cloud in ultra- low emittance regime; –Cockcroft Institute: in support of ATF and CesrTA programs, and ILC damping rings design. Issues include: alignment and stabilisation specifications; diagnostics and instrumentation functionality and performance; design of coupling correction system; development of effective tuning techniques... 22.01.2008 - INFN LNF Global Design Effort 19

20. Damping Rings Design and Costing (1) Significant progress is being made with a CAD model for the present baseline lattice. 22.01.2008 - INFN LNF Global Design Effort 20 Gate Valves Electron Vessel Positron Vessel Straight Cylindrical Vessel Tapered Vessel Ante-Chambered Vessel Tapered Vessel Pumping Port BPM Station (Electron) BPM Station (Positron) Gate Valves

21. Development of the CAD model provides essential information for: technical systems development (vacuum, conventional facilities...); costing and value engineering; beam dynamics studies (low emittance tuning, e-cloud...) 22.01.2008 - INFN LNF Global Design Effort 21 Damping Rings Design and Costing (2) Vessel with antechamber for e-cloud mitigation. BPM chamber with position encoders. BPM/bellows will contribute to machine impedance.

22. “Minimum Machine” Studies 22.01.2008 - INFN LNF Global Design Effort 22 Nom. RDRLow P RDRnew Low P E CM (GeV)500 Particles per bunch, N (×10 10 )2.0 Bunches per pulse, n b 26251320 Pulse repetition rate (Hz)555 Peak beam power, P b (MW)10.55.3  x (  m) 10  y (nm) 4036  x (cm) 2.01.1  y (mm) 0.40.2 Traveling focusNo Yes  x (nm) 640474  y (nm) 5.73.8  z (  m) 300200300 Beamstrahlung*  E/E 0.0230.0450.036 Luminosity* (×10 34 cm -2 s -1 )2.01.71.9

23. “Minimum Machine” Studies Main implication for the damping rings is that the “low power” parameter set makes a 3 km circumference feasible. –Number of bunches in the ring is halved. –Average current and bunch separation remain constant. Reducing the circumference makes it possible to contemplate also reducing the beam energy. –Maybe reduce from 5 GeV to 4.6 GeV, or 4.2 GeV. Reduces longitudinal emittance, with benefits for the bunch compressors. Reduces amount of wiggler, rf, magnet power, etc.  Injected beam sizes becomes larger.  Beam becomes less robust against collective effects. 22.01.2008 - INFN LNF Global Design Effort 23

24. “Minimum Machine” Studies We have two lattices that can be used as a basis for 3 km damping ring studies......one of them produced by replacing the arc cells in the present baseline lattice, with cells based on those used in SuperB. 22.01.2008 - INFN LNF Global Design Effort 24

25. Plans for TDP-I/Minimum Machine 22.01.2008 - INFN LNF Global Design Effort 25 TaskResponsibility Modify/develop 3 km damping ring lattice design.Korostelev/Biagini Evaluate dynamics in 3 km damping ring.Korostelev/Biagini Develop lattice designs for injection/extraction lines.Guiducci Continue to develop impedance model.Korostelev/Marcellini Develop and maintain CAD models.Lucas Update and maintain cost estimates.Lucas Specify and cost power distribution system.Palmer/Bellomo 1.Continue critical R&D: electron cloud; fast kickers; low emittance tuning. 2.Produce technical evaluation and cost comparison of 6 km and 3 km damping ring options, by end 2009, to support possible new baseline. 3.Continue technical design and costing work for TDR.

26. ILC-CLIC Collaboraton Differences in linac technologies drive damping rings to different configurations in ILC and CLIC, however......there are a number of high-priority issues that are common for both projects: –electron cloud mitigation; –ultra-low emittance tuning and preservation. A first step toward closer collaboration has already been taken, in coordinating CLIC and ILC damping rings WebEx meetings. A joint working group on damping rings is now being established, convened by Yannis Papaphilippou and Mark Palmer. 22.01.2008 - INFN LNF Global Design Effort ILCCLIC Energy (GeV)52.4 Circumference (m)6476365 Bunch number2700-5400312 Particles/bunch (10 10 )2.0-1.00.37 Damping time  x (ms) 211.5 Emittance  x (nm) 4200381 Emittance  y (nm) 204.1 Momentum compaction (10 -4 )1.3-2.80.80 Energy loss/turn (MeV)8.73.9 Energy spread1.3x10 -3 1.4x10 -3 Bunch length (mm)9.0 - 6.01.53 RF Voltage (MV)17 - 324.1 RF frequency (MHz)6502000 26

27. Summary Post RDR, GDE has shifted into a more formal project structure Technical Design Phase 1 (to 2010) focused on “Risk Mitigating” R&D –Electron Cloud –Fast kicker development –2pm emittance DR design work focus on cost / performance optimisation –Including 3km ring option INFN LNF has a long history of involvement/collaboration in ILC DR design work –We hope to build on this solid base in the future Global Design Effort 27 22.01.2008 - INFN LNF