ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 R&D status of ILC Positron Source KURIKI Masao (Hiroshima/KEK) ‏ 구리기 마사오 ( 히로시마 대학 )

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Table of Contents Introduction RDR baseline configuration and its R&D. Alternative configuration and its R&D. TDP for ILC positron source Summary

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Undulator Parameters

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 R&D efforts for the baseline (1) This system is a totally new approach; Feasibility of the system should be confirmed in various levels. ─Devices ─System and sub-system In addition, the ILC baseline e+ source is not an isolated system from the whole ILC and has inter-system dependencies. Careful considerations are necessary from the system point of view. ─E+ is generated at the same time for the collision. ─E+ time structure is identical to that in ML.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 R&D efforts for the baseline (2) The R&D efforts for critical devices are on going. ─Super-conducting helical undulator. ─Rotating conversion target. ─Capture devices (pending due to no budget). Several considerations from the system engineering point of view have been made. ─E+ timing issue : a mathematical puzzle among DR harmonic number, bunch spacing in ML, round trip duration from e- DR to e+ DR, etc. ─Keep Alive e+ source : machine commissioning, fast recovery from the system failure,etc.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Undulator Cryo-module Overview Stainless steel vacuum vessel with Central turret 50K Al Alloy Thermal shield. Supported from He bath Stainless Steel He bath contains100L liq He. Supported by 4 rods attached to the vacuum vessel U Beam used to support/align the magnet. U beam Support rod Magnet cooled to 4.2K by liq He in bath. Beam Tube S Carr

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Undulator Cryomodule U Beam He Vessel Heat Shield Helical Undulator

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Quench Test & Field Measurement All two magnets finally satisfied the specification. Field profile is measured by hall probe, showing a good quality.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Conversion Target Ken Davies - Daresbury Laboratory  Water-cooled electromagnet  Variable pole gap (0mm to 160mm)‏  Peak field > 1 T at wheel  15 kW drive motor  Ti alloy wheel. L Jenner  Torque Sensor Photon beam

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Target Prototype Experiment will start when personnel guards are in place Should be completed by end of 2008

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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%.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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).

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Quarter Wave Transformer Ramping from 0T to 1 T in 5cm (no field on target). Capture efficiency ~ 15%. Technically matured and realizable (actual baseline).

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 CHANNELING FOR ILC & CLIC e+ source R. 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. e-e- Crystal Amorphous e +, e -,  γ e-e- e+e+ “x” meters Only the photons are impinging on the converter: that limits the energy deposition in the amorphous target. RadiatorConverter

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Driving motor Vacuum pump Cog-wheel pump transport tubes Target head Liquid lead target 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. Liquid Pb-Sn jet in vacuum

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 ERL ERL(Energy Recovery Linac) is employed as the dedicated electron driver. ─0.48nC, 18.5ns (54MHz) ~ 26mA, E=1.8GeV ─N γ =2.3E+9 by 0.6 Jx5 CP, N e+ =2.0E+7 By a semi-CW operation (50ms), 1000 times stacking in DR is performed and Ne+=2.0E+10 is obtained.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Pulse Stacking Optical Cavity

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Pulsed Laser Injected Cavity R. Chiche

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 High power ps fiber amplifier E. Cormier

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Experiment at KEK-ATF Electron beamCSI γray e beam PD 16~28MeV 420mm Collision angle 12 degree λ:1064nm 10W=28nJ, 2.8ns spacing Pulse length : 7ps  = 30 μm Mode lock laser Finess = 780 γ/collison

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Stacking Simulation # 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. F. Zimmermann

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 CLIC Compton Scheme Collaboration on Positron Generation strongly supported by CLIC and ILC managements (J.P.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 PosiPol-Collaboration Laser-Compton has a large potential as a future technology. Many common efforts can be shared in a context of various applications. ─X-ray/SR sources for industrial and medical applications, ─Beam diagnostics with Laser, ─Polarized Positron Generation for ILC, CLIC, SuperB,.. State-of-the-art technologies are quickly evolved with world-wide synergy. PosiPol collaboration has been started in The last annual meeting was held at Hiroshima in July 08. The next meeting will be held at near CERN in 2009.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 WWW of PosiPol R&Ds Laser Compton Optical Cavity High power laser X-ray source e- source ILC, ERL Medical applications Industrial applications ERL/Ri ng 4 th Generation light source LW monitor/ Polarimetry ILC e+ CLIC e+ SuperB e+ source Material Science Scientific Application

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Minimum machine studies Re-baseline in 2010 (publish in interim report)‏ Minimum machine studies Re-baseline in 2010 (publish in interim report)‏ TDP is a multi-phase approach towards TDR. TDP-1 is focused on Risk mitigation Cost reduction TDP-2 is a real technical design phase based on the design established on TDP-1. Technical Design Phase

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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”.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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.

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Thank you for your attention. 귀하의 관심을 주셔서 감사합니다

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 TDP-2 TDP-2: -Technical requirements documentation -Technical design work  cost update -Value Engineering -Cost & Schedule -18 month period TDP-2: -Technical requirements documentation -Technical design work  cost update -Value Engineering -Cost & Schedule -18 month period

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 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. P. Logachov et al. in APAC2007 Energy/100ps GeV/mm Average power (kW) Operation point

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 RDR Source Layout Ti-alloy fast rotating target for gamma -> e+ conversion. Capture devices : AMD or QWT + L-band NC accelerator with solenoid focusing. Backup source (500MeV e-, 10% intensity).

ASIA ILC R&D seminar Kympok National University, Taegu, Korea October 2008 Flux Concentrator for KEB upgrade