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A. Brachmann and J. C. Sheppard SLAC April 30, 2007

April 2007 DOE/NSF ART Review - ILC Polarized Electron Source and Positron Source FY06 Summary, FY07 Status and FY08-09 Proposal WBS 2.3, 3.3, 2.4, 3.4. A. Brachmann and J. C. Sheppard SLAC April 30, 2007. Nominal Source Parameters. DOE/NSF FY07 Review Polarized Electron Source – ART

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A. Brachmann and J. C. Sheppard SLAC April 30, 2007

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  1. April 2007 DOE/NSF ART Review -ILC Polarized Electron Source and Positron Source FY06 Summary, FY07 Status and FY08-09 ProposalWBS 2.3, 3.3, 2.4, 3.4 A. Brachmann and J. C. Sheppard SLAC April 30, 2007

  2. Nominal Source Parameters

  3. DOE/NSF FY07 Review Polarized Electron Source – ART FY06/07 Summary FY08/09 Planning (A. Brachmann, SLAC)

  4. Polarized Electron SourceWBS Overview • WBS 2.3 Design • WBS 3.3 R&D • WBS 3.3.1.1. Source Laser R&D • WBS 3.3.1.2. Polarized Gun Development • WBS 3.3.1.3. Photocathode Development

  5. Polarized Electron SourceFY06/07 Summary • WBS 2.3 Source design (beam dynamics simulations) to support injector layout (RDR level) • Electron Gun • Bunching System • NC/SC acceleration • eLTR with Spin precession/rotation • RF energy compression

  6. Polarized Electron SourceFY07 Summary • WBS 3.3.1 Source laser system design • Completed facility • 3 MHz pulse train generation using a modelocked Ti:sapphire laser • Start pulse train amplification work

  7. Polarized Electron SourceFY07 Summary • WBS 3.3.3 Photocathode R&D • Gridded Photocathodes (external bias for QE and polarization enhancement) • Development of Faraday rotation experiment to study depolarization mechanism • Alternative materials GaN, InGaP/GaAs Superlattice • Atomic hydrogen cleaning system development

  8. Polarized Electron SourceFY08/09 proposal – WBS 2.3 - Design • Polarized electron source design • Focus is EDR • Subsystem design and engineering • Laser/Gun/Photo-cathodes strongly related to outcome of R&D program • Trans-relativistic region • Design is at stage of complete Parmela/MAD/Elegant simulations • Engineering and system integration part of the EDR project phase • 5 GeV booster linac assumes copy of linac technology  no extra effort in FY08/09 • LTR design is shared between e- and e+  shared effort

  9. Polarized Electron Source FY08/09 proposal – WBS 3.3.1.1 Laser Development • FY 08 • Main R&D Program is the Development of the Amplifier High power cw pump laser and regenerative cryo-cooled Ti:Sapphire amplifier stage • FY09 • Complete Amplifier • Address technical challenges • Use laser system and (existing SLC) gun to generate polarized e- bunch train

  10. Polarized Electron Source FY08/09 proposal WBS 3.3.1.2 – Gun Development Project will receive first ILC funding in FY08 Use resources at Jlab to develop gun technology • Min 140 kV operating voltage (200+ kV design) • Combine features of SLC and JLAB gun (HV Design/Power Supply/Loadlock) • Testing can be done at JLAB and/or SLAC

  11. Polarized Electron Source FY08/09 proposal WBS 3.3.1.3 – Injector Development • Trans-relativistic region (bunching and pre-acceleration) • Variety of reference points (SLAC, NLCTA, TTF, …) • Many system are common with e+ source • FY08/09 program (EDR) • Transform simulations for L-band bunching into hardware design • Evaluate need for prototype of beta matched L-band TW buncher  modified 4.3 m L-band structure (used for e- and e+)

  12. Polarized Electron Source FY08/09 proposal WBS 3.3.1.4 – Photocathode R&D • Strained-superlattice GaAs-GaAsP • Polarization = 85 – 90 % • Charge limit (problem for SLC/NLC) has been overcome by high gradient doping, however, at expense of polarization • For ILC bunch charge is less, hence re-optimization of structure can lead to higher polarization (~ 5%) • Alternative materials: • AlInGaAs/GaAs (Ioffe (St. Petersburg, Russia) results: 92 % Polarization) • Large bandgap materials GaN, InGaN, AlGaN (robust and high QE) • R&D (ongoing): • Investigate depolarization mechanisms (Faraday rotation) • Additional Projects and Activities: • Cathode Test System (CTS) upgrade – Polarimeter, Cryogenic capabilities, • Use of Surface Science (XPS, SEM, etc.)

  13. Regional distribution of ILC e-source design and R&D • Americas • SLAC, JLAB • Asia • Polarized source R&D at Nagoya is in transition stage (most likely it will disappear in the near future) • KEK may pick up polarized source R&D • Europe • Various polarized source R&D programs and users • Mainz, Bonn, St. Petersburg • No direct involvement with ILC

  14. Budget WBS x.3 Electron Sources FY08: k$ 1,400 FY09: k$ 3,000 Budget is adequate for anticipated Program

  15. DOE/NSF FY07 Review ILC Positron Source – ART FY06/07 Summary and Status FY08/09 Planning (J. Gronberg, LLNL and J. C. Sheppard, SLAC)

  16. Positron Source Layout

  17. FY06/07 Summaries • Developed and promulgated ILC Positron System design for RDR • “Optimized” overall layout with respect to function, risk, and cost • Documented by writing ILC Positron System RDR chapter • Formalized international ILC Positron Collaboration (RAL/06, IHEP/07, ANL/07 Meetings) • EDR organizing and planning (ILC S5, see O. Napoly ILC MAC talk 04/07)

  18. ILC Positron SourceFY07 Status • WBS 2.4. Source Design • Systems Design (production, capture, optics, collimation, accelerators, remote handling, systems specifications, start-to-end simulations) • Monitoring and Planning of R&D Activities: domestic and international (targets, OMD, undulator, Collaboration and S5 coordination)

  19. ILC Positron SourceFY07 Status • WBS 3.4. Positron Source R&D • LLNL target design for UK developments and test program • Cornell undulator development activities • ANL pulsed flux concentrator (OMD) tests; eddy current modeling for spinning target • SLAC NC SW RF Structure prototyping (C. Adolphsen)

  20. US Institutions • Institutions doing substantial work on ILC e+ development • SLAC • overall coordination & leadership • define parameters • target hall, remote handling, activation • beamline optics and tracking • NC L-Band accelerator structures and RF systems • Experiments – E166, FLUKA validation experiment • LLNL • target simulations (thermal hydraulics and stress, rotodynamics, materials) • target design (testing and prototyping) • pulsed OMD design • ANL • optics • tracking • OMD studies • eddy current calculations • Cornell • undulator design, alternative target concepts

  21. European Institutions • Institutions doing substantial work on ILC e+ development • CCLRC-Daresbury • undulator design and prototyping • beam degradation calculations • CCLRC-RAL • remote handling • eddy current calculations • target hall activation • Cockcroft and Liverpool University • target design and prototyping • DESY-Berlin • target hall activation • spin preservation • photon collimation • E166

  22. Positron SourceWBS Overview FY08/09 • WBS 2.4 Design • WBS 2.4.1 EDR • WBS 2.4.2 Systems Engineering • WBS 2.4.3 Civil Facilities Systems Coordination • WBS 2.4.4 System Modeling • WBS 2.4.5 Remote Handling • WBS 3.4 Research and Development • WBS 3.4.1. Undulator • WBS 3.4.2. Target • WBS 3.4.3. Optical Matching Device • WBS 3.4.4 Normal Conducting RF Structures

  23. Budget WBS x.4 Positron Source FY08: k$ 2543 FY09: k$ 5304

  24. Select Positron References, 1 • ILC RDR Positron Chapter: http://media.linearcollider.org/report-apr03-part1.pdf sec. 2.3, pg. 45 ff • ILC Positron Source Collaboration Meetings 1st meeting at RAL September, 2006: http://www.te.rl.ac.uk/ILC_Positron_Source_Meeting/ILCMeeting.html 2nd meeting at IHEP, Beijing January, 2007 : http://hirune.kek.jp/mk/ilc/positron/IHEP/ • ILC Notes 1. ILC Target Prototype Simulation by Means of FEM Antipov, S; Liu, W; Gai, W [ILC-NOTE-2007-011] http://ilcdoc.linearcollider.org/record/6949 2. On the Effect of Eddy Current Induced Field , Liu, W ; Antipov, S; Gai, W [ILC-NOTE-2007-010] http://ilcdoc.linearcollider.org/record/6948 3. The Undulator Based ILC Positron Source: Production and Capturing Simulation Study – Update, Liu, W ; Gai, W [ILC-NOTE-2007-009] http://ilcdoc.linearcollider.org/record/6947 • Other Notes 1. F.Zhou,Y.Batygin,Y.Nosochkov,J.C.Sheppard,and M.D.Woodley,"Start-to-end beam optics development and multi-particle tracking for the ILC undulator-based positron source", slac-pub-12239, Jan 2007. http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-12239.pdf 2. F.Zhou,Y.Batygin,A.Brachmann,J.Clendenin,R.H.Miller,J.C.Sheppard,and M.D.Woodley,"Start-to-end transport design and multi-particle tracking for the ILC electron source", slac-pub-12240, Jan 2007. http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-12240.pdf 3. A.Mikhailichenko, " Liquid metal target for ILC*."*. Jun 2006. 3pp. Prepared for European Particle Accelerator Conference (EPAC 06), Edinburgh, Scotland, 26-30 Jun 2006. Published in *Edinburgh 2006, EPAC* 816-818

  25. Select Positron References, 2 • Other Notes, cont’d 4. A.A. Mikhailichenko <http://www-spires.slac.stanford.edu/spires/find/wwwhepau/wwwscan?rawcmd=fin+%22Mikhailichenko%2C%20A%2EA%2E%22>, "Test of SC undulator for ILC.",Jun 2006. 3pp. Prepared for European Particle Accelerator Conference (EPAC 06), Edinburgh, Scotland, 26-30 Jun 2006. Published in *Edinburgh 2006, EPAC* 813-815. 5. A.Mikhailichenko, "Issues for the rotating target", CBN-07-02, 2007, http://www.lns.cornell.edu/public/CBN/2007/CBN07-2/CBN07-2.pdf 6. A.Mikhailichenko, "Positron Source for ILC:A perspective", CBN-06-06, 2006, http://www.lns.cornell.edu/public/CBN/2006/CBN06-1/CBN06-1.pdf 7. Preliminary Investigations of Eddy Current Effects on a Spinning Disk, W.T. Piggott, S. Walston, and D. Mayhall. UCRL-TR-224467, Sep. 8, 2006 8. Positron Source Target Update, W.T. Piggott, UCRL-PRES-227298, Jan. 16, 2007. 9. Computer Calculations of Eddy-Current Power Loss in Rotating Titanium Wheels and Rims in Localized Axial Magnetic Fields. D.J. Mayhall, W. Stein, and J. Gronberg, UCRL-TR-221440, May 17, 2006 10. A Preliminary Low-Frequency Electromagnetic Analysis of a Flux Concentrator, D.J. Mayhall, UCRL-TR-221994, June 13, 2006

  26. Electron and Positron Sources End of Formal Presentation Additional info as needed

  27. Positron Plans Backup and Breakout Discussion Slides

  28. FY 06 WBS 3.3.2 Photocathode R&D - Biased Photocathodes (SBIR with Saxet Inc.) Biased photocathodes (thin unstrained GaAs) • Bias across Photocathode using metal grid • forward bias  QE ↑ • negative bias  QE, Polarization ↓

  29. Major Issues • Target design, prototyping needed • integrity • target spinning mechanical effects • pulsed OMD • thermal stress cooling design • activation and radiation damage • vacuum, water couplings • eddy current heating effects • target hall remote handling • OMD • baseline is pulsed because we do not completely understand effects of DC magnetic field on target • Beam loss in beamlines • collimation schemes • Undulator prototyping needed to ensure specs are met

  30. Meetings • Regular meetings • 10.30AM (PST) Wednesdays - positrons • ANL, LLNL, SLAC,Cornell • Alternate between hardware issues and optics • Maybe expand the invitation list • 08.00 AM (PST) Thursdays - target • SLAC, Daresbury, RAL, DESY-Z, ANL, LLNL • Alternate between target design & hall activation • 08.00 AM (PST) Wednesdays – E166

  31. Positron RDR Update • Positron RDR , in good shape • Numbers need to be checked and finalized • Figures are fine, one or two could be even better • April 1 deadline for complete RDR draft • June or so for non-draft RDR & paper version • EDR plans being hatched.. • E166 getting closer to publishing!!!

  32. Positron Collaboration Meeting • ILC Positron Source Collaboration Meeting • Collaboration to meet three times a year • 1st meeting at RAL last November • Main web page: http://www.te.rl.ac.uk/ILC_Positron_Source_Meeting/ILCMeeting.html • 2nd meeting in Beijing before GDE meeting • Main web page : http://hirune.kek.jp/mk/ilc/positron/IHEP/ • Summaries: http://hirune.kek.jp/mk/ilc/positron/IHEP/summary.html • 19 attendees , 6-9-4 USA-Europe-Asia , 2 from SLAC : John & Feng)

  33. Target Summary Topic Action Items: A. Target Systems (I. Bailey/ T. Piggott) • Source alternative magnet solutions for first proposed UK target prototype - Ian B to coordinate. • LLNL to evaluate DL target prototype design for vibrational modes and compatibility with water-cooling design (flow rates, etc) - Tom P to coordinate. • Rationalise proposed UK prototyping wrt available funding - Ian B to coordinate. • Continue evaluation of alternative target materials - Chris D to coordinate. • Seek further clarification from BINP on their 1ms OMD work - Vinod B to coordinate. • Adopt common geometry for eddy current simulations (based on UK prototype?) - Jeff G to coordinate. • Beam window issue remains unresolved? Wei + Alexander to discuss.

  34. Target Wheel

  35. Target Hall Summary Topic Action Items: • D. Target Hall (I. Bailey on behalf of V.B.) • Evaluate dose rates for short times after shutdown (1 hour, 1 day) - Andriy (DESY) • Complete detailed target station geometry for FLUKA - Luis (DL) • Include material absorption effects in FLUKA simulations - Andriy (DESY) • Carry out benchmarking of FLUKA using Ti alloy at SLAC - John (SLAC) • Get feedback on impact of 53 hour changeover on availability - Vinod (SLAC) • Evaluate need to include photon collimator in remote-handling module - Lei (Liverpool) • Evaluate activation of water in water-cooled systems - Andriy (DESY) • Evaluate shielding requirements compatible with 53 hour remote-handling schedule - Andriy (DESY) • Evaluate achievable vacuum. Assess need to evolve pillow seal design. - Ian (Liverpool) • Does ILC plan to have a central hot cell facility? - Vinod (SLAC) • Develop detailed remote-handling scenarios - Mike W (RAL) • Assess need for remote-handling for KAS - Vinod (SLAC)

  36. Target Remote Handling Estimated 53 hour replacementtime

  37. Optical Matching Device (OMD) • Optical Matching Device • factor of 2 in positron yield (3 if immersed target) • DC solenoid before target or pulsed flux concentrator after target • Pulsed device is the baseline design • Target spins in the magnetic field of the OMD • Eddy currents in the target – need to calculate power • Magnetic field is modified by the eddy currents – effect on yield?? • Eddy current mitigation • Reduce amount of spinning metal • Do experiment to validate eddy current calculations • Look for low electrical / high thermal conductivity Ti-alloys • Other materials such as ceramics • No OMD • Use focusing solenoidal lens (1/4 wave) – lower fields • OMD is upgrade to polarization!!!!!

  38. Eddy Current Experiment Proposed experiment Layout at Cockcroft Institute/Daresbury (this summer) Eddy current calculation mesh - S. Antipov, W. Liu, W. Gai - ANL

  39. Calculated Eddy Current Power Nominal RPMs

  40. Target Progress • Baseline target/capture • RAL, ANL and Cornell have done Eddy current simulation which produce consistent results with multiple codes. Estimates for power dissipation in the target are >100kW for a constant field and are considered excessive. • Evaluation of ceramic target material is on-going. No conclusions. • Radiation damage of the superconducting coil is still TBD but may not be worthwhile unless a solution can be found for the eddy currents. • ANL simulation of beam heating in windows shows that an upstream window is feasible but a downstream window is not. • Alternative target/capture • Capture efficiency for the lithium lens focusing and ¼ wave solenoid is still TBD • Thermal heating and stress for the lithium lens is still on-going. • Thermal stress calculation for the liquid metal target is still on-going

  41. OMD • Plans and Actions (baseline target/capture): • ANL will simulate eddy currents in the pulsed magnet configuration. • UK will evaluate suitability of non-conducting materials for the target • Daresbury/Cockroft/RAL will spin a one meter target wheel in a constant magnetic field and will measure the forces. • Eddy simulations will be calculated and benchmarked against this configuration • Plans and Actions (alternative targets/capture): • ANL will determine the capture efficiency for ¼ wave focusing optics and lithium lens. • LLNL will evaluate the survivability of lithium lens to beam stress • Cornell will specify an initial design of a liquid metal target. LLNL will calculate the Stress-strain behavior of the outgoing beam window.

  42. Optics • Source optics laid out. Need to look at details • Beam loss and collimation • Component interferences (target halls, DR injection) • Refine and document optics and beam physics

  43. FLUKA Validation Experiment

  44. FLUKA Validation Experiment • SLAC/CERN Collaboration (RP groups) • Validation of FLUKA activation calculations • 100 W • 30 GeV electron beam in ESA at SLAC • Cylindrical copper dump • Samples around the dump (including a Ti-4V-6Al) • Look mr/hour and gamma spectrum from irradiated samples • Run at the beginning of April …

  45. Experiment Setup

  46. Preliminary Data: Ti and Ti-alloy

  47. STATUS OF CORNELL UNDULATOR PROTOTYPING Alexander Mikhailichenko, Maury Tigner Cornell University, LEPP, Ithaca, NY 14853 A superconducting, helical undulator based source has been selected as the baseline design for the ILC. This report outlines progress towards design, modeling and testing elements of the needed undulator. A magnetic length of approximately 150 m is needed to produce the desired positron beam. This could be composed of about 50 modules of 4 m overall length each. This project is dedicated to the design and eventual fabrication of one full scale, 4 m long undulator module. The concept builds on a copper vacuum chamber of 8 mm internal bore

  48. Fig.1;Extensible prototype concept for ILC positron undulator . Diameter of cryostat =102mm

  49. Undulator cold mass design Fig.2:Details of design. 1–Iron yoke, 2–Copper collar, 3, 4–trimming Iron nuts. Inner diameter of Copper vacuum chamber is 8mm clear.

  50. Several 40 cm long undulator models with 10 and 12 mm period, Ø8 mm clear bore have been made and measured. See Table OFC vacuum chamber, RF smoothness *) Wire – Ø0.6 mm bare; **) Wire – Ø0.4 mm bare; ***) Wire – Ø0.3 mm bare Fig.3: Field profile – conical ends. 6 layer, 12 mm period – orthogonal hall probes. 1Tesla full scale For aperture diameter 5.75 mm we expect: for period 8mm – K~0.4 ; for period 10mm -K~0.9

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