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e + ソースの現状

e + ソースの現状. シカゴ GDE meeting に向けて. 大森 GDE 活動報告会 2008 年 10 月 6 日. 大森 GDE 活動報告会 2008 年 6 月 23 日. かなりの数のスライドが、栗木さんが先ごろ大邱 "2nd Asia ILC R&D Seminar, Sep 29-30, 2008" で行った公演のスライドからの、借用です. Working Groups and Conveners ILC08 - Accelerator 1. Sources Axel Brachmann, Jim Clarke.

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e + ソースの現状

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  1. e+ソースの現状 シカゴGDE meeting に向けて 大森 GDE 活動報告会 2008年10月6日 大森 GDE 活動報告会 2008年6月23日 かなりの数のスライドが、栗木さんが先ごろ大邱 "2nd Asia ILC R&D Seminar, Sep 29-30, 2008" で行った公演のスライドからの、借用です

  2. Working Groups and Conveners ILC08 - Accelerator 1. Sources Axel Brachmann, Jim Clarke

  3. ILC and Positron Source • Undulator is the baseline design. • Two alternatives: • Conventional (electron driven) is a fall back. • Laser Compton is an advanced alternative. • Any schemes are not fully established. Need a certain amount of R&D for ILC positron source. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  4. Baseline Design • It relies upon gamma rays generated by passing 150 GeV electron through 168m undulator. • Undulator is “inserted” to part way of ML (150GeV). • A positron source driven by 0.5 GeV electron is a back up for high availability and machine commissioning. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  5. Undulator Parameters M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  6. Matching Device • The generated positrons is a point like with a large transverse momentum spread. • That should be converted to a parallel beam for further acceleration; The matching device does it. • Depending on the matching device, it increases capture efficiency from 10% to 40%. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  7. DC Solenoid • High field (6T) and high capture efficiency(30%). • Similar to other DC SC magnets; It is technically matured. • It is not feasible for ILC since 100's of kW of eddy current in a fast rotating metal target. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  8. Shielded Flux Concentrator • Ramping from 0T to 7 T in 2cm (no field on target). • Capture Efficiency ~21% • Difficult technically to sustain 1ms pulse train length. • Further study needed to prove feasibility (prototype). M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  9. Quarter Wave Transformer • Ramping from 0T to 1 T in 5cm (no field on target). • Capture efficiency ~ 15%. • Technically matured and realizable (actual baseline). M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  10. Summary for baseline • R&D efforts for critical devices are in progress (undulator, target, etc). • Although Matching device is one of the most important, the R&D is stopped. • QWT is the only realistic solution at this moment and it should be actual baseline as long as there is no big progress on R&D for MD. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  11. Alternative Design • e- driven scheme (conventional) and Laser Compton scheme are considered to be alternative schemes. • e- driven scheme is a back-up alternative. • Laser Compton is an advanced alternative. • Because the baseline design is a totally new approach, a conservative alternative is very important as a technical backup. • Laser Compton is attractive, but it is technically immature; It is advanced alternative. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  12. e- driven scheme • e- drive beam impinges on a conversion target. • 6 GeV 2E+10 e- bunch. • Amorphous W (W-Re alloy), crystalline W, diamond, liquid Pb-Sn,etc. • Capture devices. • E+ booster up to 5 GeV: The technology depends on the pulse structure; SC for long pulse case (~1ms) and NC for short pulse case (<50μs). • The most important and difficult issue is conversion target. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  13. CHANNELING FOR ILC & CLIC e+ sourceR. Chehab • A single target works for CLIC, but multi-target is needed for ILC limited by PEDD. • A single target might work for ILC in Low P parameter. “x” meters e+ Only the photons are impinging on the converter: that limits the energy deposition in the amorphous target. γ e- e+, e-,  e- Crystal Amorphous Radiator Converter M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  14. Liquid lead target Driving motor • A prototype in BINP has been operated 20000h without any troubles. • Pb 90% Sn 10%, 300˚C, Cog-wheel pump. • Brazing technique for BN window has been established. Cog-wheel pump Vacuum pump Target head Liquid Pb-Sn jet in vacuum transport tubes M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  15. Liquid Pb-Sn Target • Liquid Pb target + BN window is very strong against high peak power, but less average power. • Pulsed operation (e.g. 100 bunches with 6.2ns spacing, 0.6μs, 150Hz) moderates thermal effects. • In the pulse operation, capture efficiency is higher and incident electron can be fewer. Average power (kW) Operation point Energy/100ps GeV/mm21012 • P. Logachov et al. in APAC2007 M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  16. Laser Compton Scheme • A few GeV (1.8GeV for example) electron bunch collides with 1μm laser photon stored in optical cavity. • Several 10s MeV gamma impinges in a conversion target. • A dedicated electron driver is reasonable. • Obtaining enough positron, is a technical challenge. • High intensity electron beam: Linac, Storage ring, ERL • High intensity photon beam: High power laser, optical cavity. • Stacking scheme: DR stacking, Pre-DR, etc. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  17. Compton Ring • A storage ring for electron driver:5.3nC, 6.2ns, 1ps, 1.8GeV, 0.6Jx5CP. • Positron bunch(Ne+:2.0E+8) is generated. • 10 bunches are stacked on a same bucket. This process is repeated 10 times with 10ms interval for beam cooling. • Finally, Ne+:2E+10 is obtained. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  18. ERL • ERL(Energy Recovery Linac) is employed as the dedicated electron driver. • 0.48nC, 18.5ns (54MHz) ~ 26mA, E=1.8GeV • Nγ=2.3E+9 by 0.6 Jx5 CP, Ne+=2.0E+7 • By a semi-CW operation (50ms), 1000 times stacking in DR is performed and Ne+=2.0E+10 is obtained. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  19. Stacking Simulation F. Zimmermann • # of positron by a single collision is not sufficient -> need stacking. • Stacking simulation in DR (multi-turn injection) shows 10.6% of injected e+ are lost! stacking efficiency ~90%. • The tolerance of the injection loss would be qualified. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  20. CLIC Compton Scheme • Collaboration on Positron Generationstrongly supported by CLIC and ILC managements (J.P. Delahaye@PosiPol08) by F. Zimmermann & L. Rinolfi M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  21. ILC Positron Source:MM • Undulator is moved to the end of ML (250GeV). • Energy scan <100GeV is difficult. • Dedicated pulse for e+ generation with ½L. • QWT instead of AMD, which has lower capture efficiency; The undulator length is 350m. • KAS share the common target with gamma1 source; yield is only 1% of the nominal intensity. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  22. Further Considerations on MM • Improved Low P parameter : half # of bunches in a pulse. • It is a big fair wind for the electron driven. • Potential target damage, which is the most serious issue on electron driven scheme, is relaxed. • There are active R&D on noble ideas. • No doubts that Conventional is really “conventional”. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  23. TDP Summary • Basic R&D is very important in TDP1. • Re-baseline at the end of TDP-1 is the mile-stone. • According to the investigation based on the latest technology, the status is: • The conventional method is important as a fall-back. Low P parameter and noble target technologies make it feasible and reliable. • Technical difficulty forces the undulator system bigger and bigger and it does not seem “mimimal machine”. • From the pure technical point of view, the baseline is the electron driven and undulator and laser compton are upgrade alternatives. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

  24. Summary • R&D status of ILC positron source is reviewed. • Undulator scheme is the baseline design. • SC helical Undulator, rotating rim target prototype. • Need study for matching device. • e- driven scheme is important as a backup. • There are several active R&Ds based on noble ideas. It is the best scheme for MM. • Laser Compton is an advanced alternative. • Aggressive R&D efforts. • Still need more technical maturity. • ILC-CLIC collaboration. M. Kuriki, 2nd Asia ILC R&D Seminar, Sep 29-30, 2008

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