International Linear Collider Research Plans for CESR

1. International Linear Collider Research Plans for CESR Mark Palmer Cornell Laboratory for Accelerator-Based Sciences and Education

2. Outline • International Linear Collider Overview • Preparing for the Engineering Design Report (EDR) • ILC R&D at Cornell • ILC Damping Rings R&D in Detail • CesrTA Proposal • Overall Scope • Damping Rings R&D Using CESR • Concept and Goals • Ring Modifications • Parameters and Experimental Reach • Collaborators and Projects • Schedule • Synergies with Other Parts of the CLASSE Program • Acknowledgments and Conclusion LEPP Accelerator Seminar

3. Basic Numbers 500 GeV – upgradeable to 1 TeV 14 kHz Collision Rate Luminosity: 2x1034 cm-2s-2 31 km end-to-end length 31.5 MV/m SRF cavities 16K Cavities 2K Cryostats Machine Configuration Helical Undulator polarized e+ source Two 6.7 km damping rings in central complex RTML running length of linac 11.2 km Main Linac Single Beam Delivery System 2 Detectors in Push-Pull Configuration The ILC LEPP Accelerator Seminar

4. ILC Program • ICFA Release of Reference Design Report (RDR) • Release Date: February 8, 2007 • Draft available at: http://www.linearcollider.org • Press Release: http://www.interactions.org/cms/?pid=1024912 • RDR Cost Estimate (accelerator complex): • $1.8bn site costs (eg, tunneling) • $4.9bn technology and component costs • 13K person-years of effort (personnel costs not in above numbers) • Start of the Engineering Design Phase • Engineering Design Report (EDR) in early 2010 • Complete critical R&D (eg, SRF cavity gradient yield for ML, electron cloud and fast kicker technology for DR) • Basic engineering design LEPP Accelerator Seminar

5. R&D Efforts Helical Undulator Polarized Positron Source Ring-to-Main Linac Low Emittance Transport (RTML and Main Linac) Damping Rings SRF Detector (TPC) Also management contributions ILC Work at Cornell LEPP Accelerator Seminar

6. ILC R&D at Cornell • Helical Undulator (A. Mikhailichenko) • Polarized Positron Source • Located at 150 GeV point in electron main linac • Parameters • Length ~ 200 m • K = 0.7 •  = 10 mm • Aperture = 8 mm LEPP Accelerator Seminar

7. Low Emittance Transport RTML Bunch Compressor Spin Rotator Main Linac RTML Design G. Dugan, D. Rubin, D. Sagan, J. Smith BMAD/ILCv curve shows error bars ILC R&D at Cornell LET Benchmarking (J. Smith) LEPP Accelerator Seminar

8. Damping Rings Simulation Electron Cloud and Ion Effects Technical Systems (wigglers, kickers, instrumentation…) CesrTA Development J. Alexander, M. Billing, G. Codner, J. Crittenden, G. Dugan, M. Ehrlichman, D. Hartill, R. Helms, R. Holtzapple, J. Kern, Y. Li, R. Meller, M. Palmer, D. Rice, D. Rubin, D. Sagan, L. Schachter, E. Tanke, M. Tigner, J. Urban ILC R&D at Cornell J. Urban LEPP Accelerator Seminar

9. ILC R&D at Cornell • SRF Cavities • Facilities: BCP, EP, HPR, Cavity Test • Re-entrant cavity development • Basic R&D on Niobium Cavities • 650 MHz RF for Damping Rings • SRF Group Exceeds 50MV/m LEPP Accelerator Seminar

10. ILC R&D at Cornell • Detector Development • Prototype Time Projection Chamber (TPC) • R. Galik, D. Peterson LEPP Accelerator Seminar

11. Outline • International Linear Collider Overview • Preparing for the Engineering Design Report (EDR) • ILC R&D at Cornell • ILC Damping Rings R&D in Detail • CesrTA Proposal • Overall Scope • Damping Rings R&D Using CESR • Concept and Goals • Ring Modifications • Parameters and Experimental Reach • Collaborators and Projects • Schedule • Synergies with Other Parts of the CLASSE Program • Acknowledgments and Conclusion Focus for remainder of talk will be on ILC Damping Rings Efforts! LEPP Accelerator Seminar

12. The ILC Damping Rings OCS v6 TME Lattice 2 pm-rad geometric emittance 250 km main linac bunch train is “folded” into the DRs Circled items play a key role in our local R&D plans… LEPP Accelerator Seminar

13. Present ILC DR Layout e- ring circulates in opposite direction in same central tunnel LEPP Accelerator Seminar

14. Damping Rings R&D Issues Slide from BILCW07 talk by J. Urakawa • The RDB S3 group has reviewed 76 R&D objectives for the damping rings, and identified 11 as "Very High Priority". These fall into the categories of: • injection/extraction kickers; • electron cloud effects; • impedance and impedance-driven instabilities; • lattice design (for good dynamic aperture, etc.); • tuning and maintaining low vertical emittance; • ion effects. • Development of a detailed R&D plan is in progress, detailing objectives, resources, milestones and timescales. • So far, draft work packages have been produced for the fast injection/extraction kickers; electron cloud studies; studies of impedance and impedance-driven instabilities. • The R&D program at present test facilities (notably, KEK-ATF) could be strengthened by future test facilities (e.g. CESR-ta and HERA-DR). • With over 25 institutions and 150 people interested or already involved, coordination of R&D efforts is a significant issue. Cornell R&D Meeting, September 2006 Frascati R&D Meeting, March 2007

15. Highlight One Issue • Electron Cloud • What is it? • Primary electrons can be produced as photoelectrons from synchrotron radiation, by gas ionization, and by lost beam particles striking the vacuum chamber wall • Secondary electrons are produced when free electrons are kicked by the beam and strike the vacuum chamber walls • Large amplification factors are possible and an electron cloud results • Positively charged beams are particularly susceptible to emittance growth and instabilities if the cloud density is high • The cloud particles can be trapped by the fields of the magnets around the ring • Very strong fields in wigglers • Cloud growth is very sensitive to the average currents and bunch structure in the ring LEPP Accelerator Seminar

16. Moving to a Single Positron DR M. Pivi ILCDR06 No additional suppression techniques assumed in dipoles and wigglers! Cloud density near (r=1mm) beam (m-3) before bunch passage, values are taken at a cloud equilibrium density. Solenoids decrease the cloud density in DRIFT regions, where they are only effective. Compare options LowQ and LowQ+train gaps. All cases wiggler aperture 46mm. LEPP Accelerator Seminar

17. Suppressing Electron Cloud in Wigglers Submitted to PRSTAB Design & test of impedance is under the way, test in PEPII Dipole & CESR Wiggler Strip-line type Wire type Suetsugu’s talk Calculation of the impedance ( Cho, Lanfa) L. Wang ILCDR06 Wire type Strip-line type LEPP Accelerator Seminar

18. CesrTA Proposal • Overall Scope • Damping Rings R&D Using CESR • Concept and Goals • Ring Modifications • L0 and L3 Layout Changes • Instrumentation Changes • Parameters and Experimental Reach • Baseline Lattice • Research Directions • Collaborators and Projects • Schedule LEPP Accelerator Seminar

19. ILCDR R&D Issues and CesrTA • Some High and Very High Priority R&D Items that Can Be Addressed at CesrTA… • Electron Cloud • Growth in quadrupoles, dipoles, and wigglers • Suppression in quadrupoles, dipoles, and wigglers • Instability thresholds and emittance growth in the positron damping ring • This issue has become more significant due to the decision to employ a single positron damping ring • Ion Effects • Instability thresholds and emittance growth in the electron damping ring • Ultra-low Emittance Operation • Alignment and Survey • Beam-based Alignment • Optics Correction • Measurement and Tuning • Fast (single bunch) high voltage kickers for injection/extraction • >100 kV-m of stripline kick required • <6 ns wide pulse into a 0.3 m long stripline so as not to perturb neighboring bunches in the damping ring • Development of 650 MHz SRF System LEPP Accelerator Seminar

20. CesrTA Concept • Reconfigure CESR as a damping ring test facility • Move wigglers to zero dispersion regions for low emittance operation • Open up space for insertion devices and instrumentation • Provide an R&D program that is complementary to work going on elsewhere (eg, KEK-ATF) • Provide a vehicle for: • R&D needed for EDR decisions (EDR R&D completion by end of 2009 is ILC target) • Operating and tuning experience with ultra-low emittance beams • DR technical systems development • Provide significant amounts of dedicated running time for damping ring experiments LEPP Accelerator Seminar

21. CesrTA Operating Model • Experimental Model • Collaboration among international researchers (similar to HEP collaborations) • Cornell provides machine infrastructure and support • Cornell provides operations staff • Scheduling Model • Provide multiple dedicated experimental periods each year • Provide sufficient scheduled down time to flexibly upgrade machine and install experimental apparatus • Alternate running periods with CHESS LEPP Accelerator Seminar

22. CesrTA Goals • Primary Goals • Electron cloud measurements • e- cloud buildup in wigglers • e- cloud mitigation in wigglers • Instability thresholds • Validate the ILC DR wiggler and vacuum chamber design (critical for the single 6 km positron ring option) • Ultra-low emittance operations and beam dynamics • Study emittance diluting effect of the e- cloud on the e+ beam • Detailed comparisons between electrons and positrons • Also look at fast-ion instability issues for electrons • Study alignment issues and emittance tuning methods • Emittance measurement techniques • ILC DR hardware development and testing • ILCDR wiggler prototype, wiggler vacuum chamber, alignment & survey techniques, instrumentation, etc. Possibly 650 MHz SRF and kickers. LEPP Accelerator Seminar

23. CesrTA Ring Modifications • Place all wigglers in zero dispersion regions • Wigglers in L1 and L5 straights can remain in place • Emittance scaling for wiggler dominated ring: • Provide support for short bunch length operation • Additional pair of SRF cavities in L0 (similar to CESR-c short bunch length plan) • Upgrade instrumentation and diagnostics for planned experiments LEPP Accelerator Seminar

24. CESR Modifications • Move 6 wigglers from the CESR arcs to the North IR (zero dispersion region) • New cryogenic transfer line required • Zero dispersion regions can be created locally around the wigglers left in the arcs • Make South IR available for insertion devices and instrumentation • Instrumentation and feedback upgrades LEPP Accelerator Seminar

25. The North IR 18 m region for wigglers and instrumented vacuum chambers • North IR Modifications: • Remove vertical separators and • install 6 wigglers • Add cryogenics capability • Instrumented vacuum chambers for • local electron cloud diagnostics • Eventual test location for prototype • ILC damping ring wiggler and • vacuum chambers • Move present streak camera • diagnostics area to South IR LEPP Accelerator Seminar

26. South IR Configuration: Approx. 14 m of insertion devicespace available after CLEO removal Deferred until 2010 at earliest Cryogenics infrastructure available Support for beam instrumentation Instrumentation Streak camera and optics table relocated to CLEO pit and shielded for beam-on access Center of CLEO is potential location for a laser wire monitor (if we decide to pursue such an option) South IR With CLEO in place: Prototype TPC (cosmic ray tests) SRF Cavity for Short Bunch Ops Synch Light Mirror Preserve ability to operate CLEO solenoid Q1 Q2 Vacuum chamber passes through CLEO bore LEPP Accelerator Seminar

27. Instrumentation for Ultra-Low Emittance Measurement • Typical Beam Sizes • Vertical: sy~10-12 mm • Horizontal: sx ~ 80 mm (at a zero dispersion point) • Have considered laserwire and X-ray profile monitors • Fast X-ray imaging system (Alexander) • Core diagnostic for CesrTA – high resolution and bunch-by-bunch capability • Plan for integrating systems into CHESS lines • First pinhole camera tests were successful! (see next slide) • Laserwire • CESR-c fast luminosity monitor offers window suitable for laserwire use • Detector potentially could be used for fast segmented readout of Compton photon distribution LEPP Accelerator Seminar

28. GaAs Detector for X-ray Imaging First bunch-by-bunch beam size data in CHESS conditions a Significant CHESS support Signal (ADC Counts) • = 142 +/- 7 mm Different symbols represent different bunches Pinhole camera setup at B1 hutch Fast enough for single bunch resolution Position (mm) • NEW: GaAs arrays from • Hamamatsu • 1x512 linear array • 25 mm pitch • 1st sample has just arrived LEPP Accelerator Seminar

29. zone plate detector 25um Be Multilayer W/C mirrors; q p CesrTA Beamsize Monitor Concept • Simple optics • High transmission • 2 keV operation (works for both 2 GeV and 5 GeV) • Hundreds (2 GeV) to thousands (5 GeV) of photons per bunch passage • Explore other detector possibilities (eg, InSb arrays) • Collaboration with CHESS colleagues for optics and device development as well as integration with existing Xray lines LEPP Accelerator Seminar

30. CESR Modifications Summary • How extensive are the modifications? • Significant changes to the two IRs (however, certainly no more difficult than a detector and IR magnet upgrade) • Run cryogenics transfer line to the North IR (possible during operations) • Move 6 wigglers to the North IR and remove vertical electrostatic separators • Remove the South horizontal electrostatic separators – lower impedance and provide room for possible CHESS undulator installation • Upgrade feedback system for operation with 4 ns bunch spacing • Could go to 2 ns with a more substantial upgrade (new kicker required) • Upgrade instrumentation • Extend multi-bunch turn-by-turn BPM system to entire ring • Provide high resolution beam size measurement • Conversion is relatively modest • Core ring modifications (L0 and L3) will take place in a single down period • Mid-2008 • <3 months duration • Carry out key preparation work between now and April 2008 LEPP Accelerator Seminar

31. Experimental Reach Baseline Lattice LEPP Accelerator Seminar

32. Tune scans • Tune scans used to identify suitable working points Qx~14.59 Qy~9.63 LEPP Accelerator Seminar

33. Lattice Evaluation • Dynamic aperture • 1 damping time • Injected beam fully coupled • ex = 1 mm • ey = 500 nm • Alignment sensitivity and low emittance correction algorithms • Simulations based on achieving nominal CESR alignment resolutions LEPP Accelerator Seminar

34. Vertical Emittance Sensitivities(Selected Examples) LEPP Accelerator Seminar

35. Nominal Values Low Emittance Operations • Have evaluated our ability to correct for ring errors with the above lattice • Goal: ey~5-10 pm at zero current • Simulation results indicate that we can reasonably expect to meet our targets LEPP Accelerator Seminar

36. IBS Evaluation (2 GeV Lattice) Vertical Emittance (pm) Assumes coupling dominated Bunch Length (mm) Growth by 3.5x 103 x Energy Spread Horizontal Emittance (nm) LEPP Accelerator Seminar

37. Want to study ECE impact at ILC DR bunch currents 2.5 GeV lattice with sz ~ 9mm Zero current vertical emittance chosen to be consistent with above alignment simulations This emittance regime appears consistent with studying the impact of the ECE (and other effects) on emittance dilution Presently working towards more complete beam dynamics simulations Alternate Operating Point Horizontal Emittance Growth by 1.6x Vertical Emittance Bunch Length LEPP Accelerator Seminar

38. CesrTA Research Directions • Core Efforts • Electron Cloud Growth Studies – particularly in the CESR-c wigglers • Bunch trains similar to those in the ILC DR • Vacuum chambers with mitigation techniques and diagnostics • Ultra-low Emittance Operation • Alignment and Survey • Beam-based Alignment • Optics Correction • Measurement and Tuning • Beam Dynamics Studies • Detailed inter-species comparisons (use to distinguish electron cloud, ion and wake field effects) • Characterize emittance growth in ultra-low emittance beams (electron cloud, ion effects, IBS, …) • Test and Demonstrate Key Damping Ring Technologies • Wiggler vacuum chambers, optimized wigglers, diagnostics, … LEPP Accelerator Seminar

39. Proposal Collaborators Letters of intent from > 30 collaborators for direct work on CesrTA LEPP Accelerator Seminar

40. CESR-c Wiggler Modifications • Initial vacuum tests in CesrTA • Remove Cu beam-pipe • Replace with beam-pipe having • ECE suppression and • diagnostics hardware • CU/SLAC/LBNL Collaboration • Prototype ILC Wiggler and • Vacuum Chamber • Cornell/LBNL Collaboration LEPP Accelerator Seminar

41. internal FSI SM beam wall markers external FSI collider component Survey and Alignment Rapid Tunnel Reference Surveyor (RTRS) ConceptProposal submitted for ILC DR alignment and survey studies using CesrTF Tunnel Wall • Reichold • D. Urner LiCAS technology for automated stake-out process Reconstructed tunnel shapes (relative co-ordinates) LEPP Accelerator Seminar

42. Electron Cloud (and Ion) Studies • Electron Cloud and Ion Studies Underway • Collaborator Participation • Sept. 2006: M. Pivi • Jan. 2007: K. Harkay (ANL), J. Flanagan (KEKB), A. Molvik (LLNL) LEPP Accelerator Seminar

43. 0.35 mA 0.25 mA 1 mA 0.75 mA 0.5 mA e+ Beam Size vs Bunch Current 2 GeV vertical bunch-by-bunch beam size for 1x45 pattern, positrons Notice advancing onset of beam size blow up as a function of bunch current LEPP Accelerator Seminar

44. 0.35 mA Theory and measurement of instability onset Qualitative comparison: if the transverse eigen-frequency of the electron cloud becomes comparable with the corresponding betatron frequency (xc), then the transverse motion becomes unstable. Need to take into account the horizontal motion as well. See ILCDR06 Talk by L. Schachter – https://wiki.lepp.cornell.edu/ilc/pub/Public/DampingRings/CornellWorkshopTalks/Schachter.Wake-Field_in_eCloud.ppt LEPP Accelerator Seminar

45. CesrTA Schedule • Initial Focus • Electron cloud growth and suppression in wigglers • Preparations for low emittance operations through February 2009 • ILC EDR needs drive research program until early 2010 • Expect re-evaluation of program at that point • Proposal Dates: • Upgrade funds requested starting October 1, 2007 • Operations funds requested starting April 1, 2008 • Conclusion of proposal September 31, 2012 LEPP Accelerator Seminar

46. Now Until April 1, 2008 • Implement 4ns transverse feedback • R. Meller, M. Billing, G. Codner, J. Sikora • Goal: characterize 4ns performance before NSF review • Install L3 Retarding Field Analyzers (RFA) for electron cloud measurements during May down • Hope to continue a preparatory machine studies program • Continue electron cloud and ion studies • Start exploration of low emittance operations • CESR-c (existing machine layout) optics have been designed: ex ~ 6.5 nm • Early work on beam-based alignment • Prepare for wiggler vacuum chamber studies • Collaboration: SLAC, LBNL • Design and construction of new vacuum chambers is a critical path item • Segmented RFA for high field operation • General infrastructure preparation • Feedback • Cryogenics • Vacuum • Other… RFA Assembly LEPP Accelerator Seminar

47. International Linear Collider Overview • Preparing for the Engineering Design Report (EDR) • ILC R&D at Cornell • ILC Damping Rings R&D in Detail • CesrTA Proposal • Overall Scope • Damping Rings R&D Using CESR • Concept and Goals • Ring Modifications • Parameters and Experimental Reach • Collaborators and Projects • Schedule • Synergies with Other Parts of the CLASSE Program • Conclusion and Acknowledgments LEPP Accelerator Seminar

48. Synergies • Modifications that will benefit ERL@CESR • BPM system upgrade provides electronics that will be reused for the ERL • Improvements in low emittance diagnostics • Improvments in survey and alignment capabilities • Development of machine correction methods at ultra-low emittance • Potential new regimes for CHESS operations • 5 GeV low emittance lattice • 6 wiggler operation with ex ~ 26.3 nm • Requires a ~100kW Xray dump in North area • Goal is 100 mA single beam operations LEPP Accelerator Seminar

49. Unique Features of R&D at CESR CESR offers: • The only operating wiggler-dominated storage ring in the world • The CESR-c damping wigglers • Technology choice for the ILC DR baseline design • Physical aperture: Acceptance for the injected positron beam • Field quality: Critical for providing sufficient dynamic aperture in the damping rings • Flexible operation with positrons and electrons • Flexible bunch spacings suitable for damping ring tests • Presently operate with 14 ns spacing • Can operate down to 4ns (or 2ns) spacings with suitable feedback system upgrades • Flexible energy range from 1.5 to 5.5 GeV • CESR-c wigglers and vacuum chamber specified for 1.5-2.5 GeV operation • An ILC DR prototype wiggler and vacuum chamber could be run at 5 GeV • Dedicated focus on damping ring R&D for significant running periods after the end of CLEO-c data-taking • A useful set of damping ring research opportunities… • The ability to operate with positrons and with the CESR-c damping wigglers offers a unique experimental reach LEPP Accelerator Seminar

50. Conclusion • CesrTA conceptual design work is ongoing • The machine offers unique features for critical ILC damping ring R&D • CESR-c wigglers • Operation with positrons and electrons • Flexible bunch configuration • Wide range in operating energy • Simulations indicate that the emittance reach is suitable for a range of damping ring beam dynamics studies • The experimental schedule will allow timely results for ILC damping ring R&D! LEPP Accelerator Seminar