1. CESR Test Facility Plans Mark Palmer Cornell Laboratory for Accelerator-Based Sciences and Education

2. October 6, 2006 LEPP Journal Club 2 Outline The International Linear Collider –ILC Accelerator Research at Cornell –Key Issues for the ILC Damping Rings CESR as a Vehicle for ILCDR Research - CesrTF –Concept and Goals –Ring Modifications –Parameters and Experimental Reach –The R&D Program Schedule Collaborators and Projects –Local Participants Conclusion

3. October 6, 2006 LEPP Journal Club 3 The International Linear Collider Key Milestones –Costed Reference Design by the end of 2006 –Technical Design by the end of 2009 An R&D Program To… –Demonstrate the baseline design –Optimize cost and perfomance –Develop improvements to the baseline Ready in 2010 to propose construction See opening VLCW06 talk by B. Barish http://vlcw06.triumf.ca/ Baseline Layout as of July 2006

4. October 6, 2006 LEPP Journal Club 4 ILC Accelerator R&D At Cornell Ring to Final Focus - Low Emittance Transport and BBA Helical Undulator for the Positron Source Superconducting RF –Facilities: BCP, EP, HPR, Cavity Test –Re-entrant cavity development –Basic R&D on Niobium Cavities –650 MHz RF for Damping Rings Damping Rings –Simulation –Kickers –Wigglers –Instrumentation –CesrTF Simulation Tools Based On BMAD D. Sagan http://www.lepp.cornell.edu/~dcs/bmad Simulation Tools Based On BMAD D. Sagan http://www.lepp.cornell.edu/~dcs/bmad

5. October 6, 2006 LEPP Journal Club 5 ILC@Cornell: RTML and Main Linac Low Emittance Transport –Ring-to-Main Linac (RTML) –Bunch Compressor –Spin Rotator –Main Linac J. Smith BMAD/ILCv curve shows error bars Simulation Benchmarking Emittance Growth in Main Linac

6. October 6, 2006 LEPP Journal Club 6 Preliminary polarization analysis consistent with expectations Preliminary polarization analysis consistent with expectations Helical Undulator R&D Built at LEPP Length = 1 m K = 0.17 (undulator param) = 2.5 mm Aperture = 0.88 mm 0.76 T 2300 A 12  s Built at LEPP Length = 1 m K = 0.17 (undulator param) = 2.5 mm Aperture = 0.88 mm 0.76 T 2300 A 12  s E166 Undulator Length ~ 200 m K = 0.7 = 10 mm Aperture = 8 mm Length ~ 200 m K = 0.7 = 10 mm Aperture = 8 mm Build 0.3 m unit Optimize field quality Evaluate effects on emittance and polarization of e - beam Design, assemble and test Field measurement in vacuum Collaboration with Daresbury Build 0.3 m unit Optimize field quality Evaluate effects on emittance and polarization of e - beam Design, assemble and test Field measurement in vacuum Collaboration with Daresbury ILC Undulator ILC Prototype A. Mikhailichenko

7. October 6, 2006 LEPP Journal Club 7 SRF: Main Linac 9-cell Cavities Assembly Complete Vertical Test

8. October 6, 2006 LEPP Journal Club 8 Re-entrant Cavity Collaboration with KEK Re-entrant Shape Single Cell Cavity Reached 47 MV/m in Nov 04 2nd Re-entrant Cavity (built at Cornell) Treated and Tested at KEK Reached 50+ MV/m at KEK (Sept 05) V. Shemelin

9. October 6, 2006 LEPP Journal Club 9 The ILC Damping Rings Beam energy5 GeV Circumference6695 m RF frequency650 MHz Harmonic number14516 Injected (normalised) positron emittance 0.01 m Extracted (normalised) emittance8 μm × 20 nm Extracted energy spread<0.15% Average current400 mA Maximum particles per bunch2×10 10 Bunch length (rms)6 mm Minimum bunch separation3.08 ns 2 pm-rad geometric emittance OCS v6 TME Lattice Circled items play a key role in our local R&D plans… 250 km main linac bunch train is “folded” into the DRs

10. October 6, 2006 LEPP Journal Club 10 ILCDR R&D Issues Some High and Very High Priority R&D Items –Electron Cloud Growth in bend magnets and wigglers Suppression in bend magnets 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 We are in a position to make significant contributions to R&D in all of these areas at Cornell

11. October 6, 2006 LEPP Journal Club 11 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

12. October 6, 2006 LEPP Journal Club 12 Moving to a Single Positron DR 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. M. Pivi ILCDR06

13. October 6, 2006 LEPP Journal Club 13 Suppressing Electron Cloud in Wigglers Strip-line type Wire type Strip-line typeWire type Calculation of the impedance ( Cho, Lanfa) Design & test of impedance is under the way, test in PEPII Dipole & CESR Wiggler Submitted to PRSTAB Suetsugu’s talk L. Wang ILCDR06

14. October 6, 2006 LEPP Journal Club 14 CesrTF Overview CESR-c HEP operations scheduled to conclude on March 31, 2008 Design studies are presently underway to modify CESR for ILC Damping Ring R&D  CesrTF 4 Key Questions: 1.What can CESR offer as a damping ring test facility? 2.How extensive are the required modifications? 3.What is the resulting experimental reach? 4.Can important R&D results be provided in a timely fashion for the ILC TDR and (hoped for) start of construction? South (CLEO) and North Interaction Regions

15. October 6, 2006 LEPP Journal Club 15 CesrTF 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 TDR decisions (TDR complete at end of 2009) –Operating and tuning experience with ultra-low emittance beams –DR technical systems development Provide significant amounts of dedicated running time for damping ring experiments

16. October 6, 2006 LEPP Journal Club 16 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

17. October 6, 2006 LEPP Journal Club 17 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, 650 MHz SRF, kickers, alignment & survey techniques, instrumentation, etc. CesrTF Goals

18. October 6, 2006 LEPP Journal Club 18 CESR Modifications CLEO North IR South IR 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

19. October 6, 2006 LEPP Journal Club 19 The North IR 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 18 m region for wigglers and instrumented vacuum chambers

20. October 6, 2006 LEPP Journal Club 20 The South IR South IR Modifications: Approx. 14 m of insertion device space available after CLEO removal Cryogenics infrastructure available Beige volumes indicate insertion regions Support for beam instrumentation RF Cavities for short bunch length operation shown here Possible location for laserwire installation. A 0.26 X 0 Al window is available 16.1 m to the west. It is also possible to place a 2 nd window in the east.

21. October 6, 2006 LEPP Journal Club 21 Instrumentation for Ultra-Low Emittance Measurement Typical Beam Sizes –Vertical:  y ~10-12  m –Horizontal:  x ~ 80  m (at a zero dispersion point) Have considered laserwire and X-ray profile monitors –Fast X-ray imaging system (Alexander) Core diagnostic for CesrTF – 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

22. October 6, 2006 LEPP Journal Club 22 GaAs Detector for X-ray Imaging Signal (ADC Counts) Position (  m) Fast enough for single bunch resolution First bunch-by-bunch beam size data in CHESS conditions  Significant CHESS support  = 142 +/- 7  m Different symbols represent different bunches Pinhole camera setup at B1 hutch NEW: GaAs arrays from Hamamatsu 1x512 linear array 25  m pitch 1 st sample has just arrived

23. October 6, 2006 LEPP Journal Club 23 Luminosity Monitor Window Available for laserwire use Aluminum  Window –Faces into South IR –~1 in thick (0.26 X 0 ) –16.1 m from center of CesrTF insertion region –Looks at e + beam –Aperture (for 16.1 m): +/- 1.7 mrad vertical -7 to +2 mrad horizontal (negative is to inside of ring) A similar window, but with smaller horizontal aperture, could potentially be added for monitoring the electron beam

24. October 6, 2006 LEPP Journal Club 24 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) –Cryogenics transfer line must be run to the North IR –6 wigglers must be moved to the North IR –Remove the electrostatic separators (single beam on-axis operation for CesrTF and CHESS) – room for proposed CHESS undulators –Feedback amplifiers and electronics will be upgraded to allow operation with 4 ns bunch spacing Could go to 2 ns with a more substantial upgrade –Instrumentation must be upgraded Extend multi-bunch turn-by-turn BPM system to entire ring (presently single sector) High resolution emittance measurement techniques Conversion is relatively modest –Approx. 7 months of down time required (with existing laboratory resources) to remove CLEO and carry out the conversion –Key preparation work carried out between now and April 2008

25. October 6, 2006 LEPP Journal Club 25 Experimental Reach xx yy xx Wigglers ParameterValue E2.0 GeV N wiggler 12 B max 2.1 T xx 2.25 nm QxQx 14.59 QyQy 9.63 QzQz 0.098  E /E 8.6 x 10 -4  x,y 47 ms  z (with V RF =15MV) 6.8 mm cc 6.4 x 10 -3  Touschek (N b =2x10 10 &  y =5pm ) 7 minutes Baseline Lattice

26. October 6, 2006 LEPP Journal Club 26 Tune scans Tune scans used to identify suitable working points Q x ~14.59 Q y ~9.63

27. October 6, 2006 LEPP Journal Club 27 Lattice Evaluation MisalignmentNominal Value Quadrupole, Bend and Wiggler Offsets 150  m Sextupole Offsets 300  m Quadrupole, Bend, Wiggler and Sextupole Rotations 100  rad Dynamic aperture –1 damping time –Injected beam fully coupled  x = 1 mm  y = 500 nm Alignment sensitivity and low emittance correction algorithms –Simulations based on nominal CESR alignment capabilities

28. October 6, 2006 LEPP Journal Club 28 Vertical Emittance Sensitivities (Selected Examples)

29. October 6, 2006 LEPP Journal Club 29 Low Emittance Operations Have evaluated our ability to correct for ring errors with the above lattice –Goal:  y ~5-10 pm at zero current –Simulation results indicate that we can reasonably expect to meet our targets Correction TypeAverage Value95% Limit Orbit Only10.2 pm21.4 pm Orbit+Dispersion3.9 pm8.2 pm Nominal Values

30. October 6, 2006 LEPP Journal Club 30 IBS Evaluation (2 GeV Lattice) Horizontal Emittance (nm) Vertical Emittance (pm) Assumes coupling dominated Bunch Length (mm) 10 3 x Energy Spread Growth by 3.5x

31. October 6, 2006 LEPP Journal Club 31 Alternate Operating Point Want to study ECE impact at ILC DR bunch currents –2.5 GeV lattice with  z ~ 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 Horizontal Emittance Vertical Emittance Bunch Length Growth by 1.6x

32. October 6, 2006 LEPP Journal Club 32 When Will R&D Results Become Available? Immediate Plans –Complete conceptual design work and validation –Proposal submission in December –Proposal will encompass our other areas of ILC accelerator research as well as the test facility FY07 –Engineering design work –Begin fabrication of items critical for 2008 down End of scheduled CESR-c/CLEO-c physics: March 31, 2008 –Install wigglers with new vacuum chambers immediately First dedicated CesrTF run in June 2008! –Alternating operation with CHESS –Estimate ~4 months/year of operations as a DR test facility This schedule is consistent with: –Early results before TDR completion –Significant program contributions before start of ILC construction

33. October 6, 2006 LEPP Journal Club 33 The Next 1.5 Years Continue to develop the CesrTF Conversion Plan Prepare for wiggler vacuum chamber studies –Collaboration: SLAC, LBNL Machine Studies –Electron cloud and ion studies underway (see following slides) –Plan to continue such work through the end of CESR-c –Low emittance CESR-c (existing machine layout) optics have been designed:  x ~ 6.5 nm General infrastructure preparation as can be supported by manpower and funding resources FY07FY08 AprMayJunJulAugSeptOctNovDecJanFebMar Ongoing Development Work for CesrTF Retrofit 2 spare CESR-c 8-pole wigglers with new vacuum chambers Preparatory Machine Studies: Electron Cloud, Ions, Low Emittance CESR-c Optics General Preparation: Cryogenic Transfer Lines to North IR, Instrumentation,…

34. October 6, 2006 LEPP Journal Club 34 CESR-c Wiggler Modifications Initial tests in CesrTF Remove Cu beam-pipe Replace with beam-pipe with ECE suppression and diagnostics hardware SLAC/LBNL Collaboration

35. October 6, 2006 LEPP Journal Club 35 e+ Beam Size vs Bunch Current 0.5 mA 0.75 mA 1 mA 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 0.25 mA 0.35 mA

36. October 6, 2006 LEPP Journal Club 36 Theory and measurement of instability onset 0.35 mA Qualitative comparison: if the transverse eigen-frequency of the electron cloud becomes comparable with the corresponding betatron frequency ( x c), 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

37. October 6, 2006 LEPP Journal Club 37 Proposed Transition Plan Initial focus on local ECE measurements –Provides key TDR information –Provides guidance for subsequent CesrTF investigations Start exploring low emittance operations 650 MHz SRF development getting underway ILC Wiggler Prototype development getting underway FY08FY09 AprMayJunJulAugSeptOctNovDecJanFebMar DownDown CHESSCesr TF Down for North IR Conversion CHESSCesrTFDown for South IR Conversion (4 months) Install/Test 2 wigglers w/modified Vacuum Chambers Install/Test full wiggler complement (including cryo support) and vacuum diagnostics in North IR. Instrumentation and Vacuum Diagnostics Upgrades LiCAS Alignment/Survey Upgrades

38. October 6, 2006 LEPP Journal Club 38 Survey and Alignment collider component Rapid Tunnel Reference Surveyor (RTRS) Concept Proposal submitted for ILC DR alignment and survey studies using CesrTF Tunnel Wall Reconstructed tunnel shapes (relative co- ordinates) wall markers internal FSI external FSISM beam LiCAS technology for automated stake-out process A. Reichold

39. October 6, 2006 LEPP Journal Club 39 Prototype Operations Schedule Schedule along these lines presently under discussion –Provides 4 dedicated running periods prior to TDR completion Envision a 5-year NSF operations proposal: April 1, 2008 – March 31, 2013 –Last 3 years would have a similar operating schedule to the FY09-FY10 version FY09FY10 MayJunJulAugSeptOctNovDecJanFebMarApr CHESS Supporting work can occur here (eg, instrument- ation) CesrTF Flexible Operations and Machine Access DownDown CHESS Supporting work can occur here (eg, instrument- ation) CesrTF Flexible Operations and Machine Access CHESS Supporting work can occur here (eg, instrument- ation) CesrTF Flexible Operations and Machine Access Down Install ILC Proto- type Wig- gler? Running periods approximately 50% CHESS/50% CesrTF Running periods approximately 50% CHESS/50% CesrTF Running periods approximately 50% CHESS/50% CesrTF

40. October 6, 2006 LEPP Journal Club 40 Organization CesrTF will be a collaborative endeavor –LEPP will operate the machine –LEPP will also contribute to the experimental program –We expect to provide a significant fraction of the machine time to collaborator experiments –LEPP will provide accelerator physics and machine support for collaborator experiments

41. October 6, 2006 LEPP Journal Club 41 Collaborators Electron Cloud Simulation/Measurement/Suppression –M. Pivi, L. Wang – SLAC; L. Schachter – Technion; K. Harkay – ANL; K. Ohmi and J. Flannagan – KEK Wiggler vacuum chamber –S. Marks, etal. – LBNL; M. Pivi, L. Wang – SLAC Alignment and Survey –A. Reichold, D. Urner – LiCAS, Oxford Requirements and experimental plan –J. Urakawa – KEK; A. Wolski – Cockroft Institute Low emittance instrumentation –G. Blair – Adams Inst.; J. Alpert – CalTech; CHESS Colleagues Beam Dynamics Simulations –A. Wolski – Cockroft Inst., M. Pivi, L. Wang – SLAC; P. Spentzouris, etal. – FNAL; C. Celata – LBNL

42. October 6, 2006 LEPP Journal Club 42 Acknowledgments CesrTF Studies –M. Ehrlichman (Minn) –J. Shanks (REU) –R. Helms –J. Urban –D. Sagan –D. Rubin CESR Machine Studies –G. Codner –E. Tanke –L. Schachter –M. Billing –M. Forster –D. Rice –J. Crittenden

43. October 6, 2006 LEPP Journal Club 43 Conclusion CesrTF 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 We would like to extend an open invitation to anyone interested in collaborating on this project