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1 ILC accelerator related R&D in Japan 2 nd ASIA ILC R&D Seminar at KNU, Daegu, Korea Junji Urakawa, KEK 11 1. Pol. e - source R&D at Nagoya U., Hiroshima.

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Presentation on theme: "1 ILC accelerator related R&D in Japan 2 nd ASIA ILC R&D Seminar at KNU, Daegu, Korea Junji Urakawa, KEK 11 1. Pol. e - source R&D at Nagoya U., Hiroshima."— Presentation transcript:

1 1 ILC accelerator related R&D in Japan 2 nd ASIA ILC R&D Seminar at KNU, Daegu, Korea Junji Urakawa, KEK 11 1. Pol. e - source R&D at Nagoya U., Hiroshima U., and KEK 2. Pol. e + source R&D at KEK, Hiroshima U., IHEP, CERN, and LAL reported by M. Kuriki (Also, considering conventional source with KEKB upgrade plan, liquid Pb or crystal target) 3. Damping Ring R&D at ATF reported by N. Terunuma 4. BDS R&D at ATF2 reported by T. Tauchi 5. SCRF R&D at STF reported by H. Hayano and N. Ohuchi 6. Photo-cathode RF gun 7. Pulsed laser storage cavity 8. Quantum beam project

2 2 1. Pol. e- source R&D at Nagoya U., Hiroshima U., and KEK Production of nanosecond pol.e - beam for ILC Photocathode: GaAs-GaAsP SL (Pol.max > 85%) Laser energy : 6  J ( 10Hz ) Bunch width(FWHM): 1.6ns Bunch charge : 8nC Laser e - beam The SL active layer grown on a laser cutting GaAs wafer ILC:6.4nC/bunch

3 3 Extracted charge of 30nC/bunch was obtained. Space charge limit Experiments & Simulations The experimental data is a measurement of supply current to the electrode. Both results are corresponding well, therefore this simulation is almost appropriate for calculating SC effect. Experimental data Simulation data ( GPT ) Extracted charge is estimated from the number of macro-particles at 10mm downstream PC.

4 4 Characteristics of SUS and Ti-Mo electrode Dark current characteristic isn’t degraded even if many breakdowns were occurred. Hardly observed dark current until breakdown was occurred. Advantages of Ti-Mo electrode

5 5 Photocathode Lifetime Preliminary The photocathode lifetime seems no problem under the condition of a few micro amps beam emission. Gun:2.7x10 -9 Pa 2NEG:2.0x10 - 9 Pa

6 6 Long-term 200keV operation became possible by employing the titanium anode and molybdenum cathode electrode. Remaining R&D : A laser system which meets fully ILC requirements. SLAC is developing. Hiroshima, and KEK are considering.

7 7 Cs 2 Te Photo-cathode, 1.6 Cell S-band RF Gun Multi-bunch beam generation 6. Photo-cathode RF gun

8 8 Fig.5 Momentum distribution of bunch train

9 9 Fig. 7 Upper-left : ICT signal of 100 bunches, upper-right : 100 bunches on the OTR screen, bottom figure : energy of each bunch in the train 100 bunches/pulse energy spread is less than 0.5%.

10 10 S-band accelerating tube (3m) Chicane Bending magnet Q-magnet solenoid RF Gun Cathode: Cs-Te PRM: Beam Profile Monitor OTR target or Al 2 O 3 (Cr 3+ doped) Emittance measurement Beam energy and energy spread measurement Collision point BPM: Beam position monitor BPM PRM ICT Faraday Cup ICT & Faraday Cup: Beam current monitor e - beam Side view Top view Laser Pulse Stacking Chamber, 3m long S-band accelerating tube and Photo-cathode RF Gun

11 11 Emittance measurement εx: 3.0 [mm ・ mrad] εy: 4.7 [mm ・ mrad] Collision point QF1 QD1 CP1G (OTR) σ x : 86um σ y : 36um Beam profile at Collision point Beam current : 2.5nC/train, 3bunches

12 12 Optical Circuit P-LW-CAV installed in APR2007. e - beam

13 13 X-ray Generation Pulsed laser stacking chamber 43MeV end station to separate X-ray and e-beam. 33keV X-ray is deflected by Crystals.

14 14 Laser Undulator Compact X-ray (LUCX) Project at KEK-ATF Multi-bunch photo-cathode RF Gun S-band Acc. Structure Storage Laser power 40kW, 7psec(FWHM), next step :1MW Beam size at CP 60  m in  Multi-bunch e- beam 300nC at gun 43MeV Multi-bunch beam+ Super-Cavity = 33keV X-ray. X-ray Detector At present, laser waist size is 30  m in  We should reduce both beam size at CP down to 30  m. 33keV X-ray generation based on inverse Compton scattering was started from May 2007 with Super-Cavity.

15 15 50 m J / pulse, waist = 8  m laser beam e- beam 7. Pulsed laser storage cavity From two-mirror cavity to four-mirror cavity under International collaboration with LAL.

16 16 Considering two-mirror cavity, reflectance R, transmissivity T, and losses L where R+T+L = 1 by energy conservation. The “bounce number” b which is defined from the round-trip power loss in a cavity, ∝ e −1/b. FSR : free spectral range If R=R 1 =R 2

17 17 Storage of laser pulse Resonance condition : Not resonance : L ≠ L lasercavity Imperfect Resonance : L ~ L lasercavity Perfect resonance : L = L lasercavity The relationship with laser and cavity : The enhancement factor is the function of reflectivity, Δl and laser pulse width.

18 18 CW Laser wire beam size monitor in DR 14.7µm laser wire for X scan 5.7µm for Y scan (whole scan: 15min for X, 6min for Y) 300mW 532nm Solid-state Laser fed into optical cavity JFY2003 Achievement on related technique

19 19 Laser wire block diagram optical cavity resonance is kept by piezo actuator Free spectral range :532nm/2=266nm Line width=0.3nm

20 20 Laser: Mode Lock:Passive SESAM Frequency:357MHz Cavity length:0.42 m Pulse width:7.3 p sec (FWHM) Wave Length:1064 nm Power: ~ 6W SESAM: SEmi-conductor Saturable Absorber Mirrors Experimental results ( Pulse Laser Storage )

21 21 Cavity:Super Invar Cavity length:420mm Mirrors: Reflectivity:99.9%, 99.9% (maybe, 99.98%) Curvature:250 mm (ω 0 = 180μm) Ext. Cavity: 62φ super invar

22 22 ・ Finesse: R = 99.98% Finesse =πτc/l τ:decay time c: light verocity l: cavity length τ:decay time c: light verocity l: cavity length F ~ 6300 τ~ 3.0μsec PD Trans. P.C. PBS JFY 2004

23 23 e - beam laser beam pulse stacking cavity in vacuum chamber 1.Achieve high enhancement & small spot size 2.Establish feedback technology 3.Achieve small crossing angle 4.Get experinence with e - beam  -ray Generation with Laser Pulse Stacking Cavity (Hiroshima-Waseda-IHEP-KEK) We should detect 20  ’s/collision.

24 24 Mirror damage which is caused by peak power density on the mirror. Storage average power 40kW or more (maybe 120kW) Laser size on mirror 440  m Then, reduce waist size from 160  m to 60  m. Laser size on mirror 1174  m Good coating spherical mirror damage threshold : Average power density on mirror ~10 MW/cm 2 Peak power density on mirror ~10 GW/cm 2 Waist size in sigma from 80  m to 30  m damaged coating size ~100  m Depth (p-p) 5.5  m

25 25 REO and SOC mirror threshold are a little small : 6.7 GW/cm 2 and 1.6 GW/cm 2 We designed asymmetric reflective mirror configuration to increase the coupling : 99.7% and 99.9%. Then, we found damaged mirror was low reflective one. When we introduced burst mode operation for x-ray generation with F.L. pumped amplifier, we might increase average power in the cavity until 120kW. It means ~20GW/cm 2. Now we keep 40kW average power with larger beam size 1174  m on the mirror,which corresponds 0.8GW/cm 2.

26 26

27 27 R/D Status in Japan Moderate Enhancement ~ 1000 Moderate spot size ~ 30 micron Simple cavity stucture with two mirrors Get experinence with 43MeV and 1.3GeV e- beam Laser Undulator Compact X-ray (LUCX) Project at KEK-ATF 43MeV Multi-bunch beam+ Super-Cavity = 33keV X-ray. Expected X-ray is generated.

28 28 Key technology is Compact (less than 10m) quasi-monochromatic (less than 1%) High Flux ( 100 times than Compact normal Linac X-ray : 10 11 photons/sec 1% b.w. ) High Brightness (10 17 photons/sec mrad 2 mm 2 0.1% b.w. ) Ultra-short pulse X-ray ( 40 fs ~ ) Structural Nano-material Highly fine genetic analysis, evaluation, X-ray Imaging http://mml.k.u-tokyo.ac.jp/ 8. Quantum beam project Characteristic of proposed machine SCRF acceleration technology

29 29 400 times by CW operation : ERL Pulsed laser storage Storage energy : 100 times Beam size < 8  m Photo-cathode RF gun Low emittance beam 3mmmrad Short pulse, 162.5MHz bunch train Laser Inverse Compton scattering High intensity, high quality, monochromatic X-ray SCRF Cavity Ultra-low loss(10nΩ)  long pulse acceleration  high intensity and low emittance 29

30 30 0.5 m J / pulse, waist = 30  m Pulsed Laser Storage 50 m J / pulse, waist = 8  m Laser wire waist :  ~ 3  m Electron beam size :  ~ 2  m Beam orbit control Achieved by ATF From 2-mirror cavity to 4-mirror cavity 30

31 31 Organization & Responsibility U. of Tokyo Photo-cathode Input coupler JAEA 直流高電圧電子源 カソード ERL 電子源試験装置 Hitachi DC High Voltage Source Hiroshima U. Laser storage RF Gun Photo-cathode Waseda U. X-ray detector Laser Compton Exp. Compact Accelerator Committee for project evaluation 高安定電源供給 High Quality and Intensity e- source Pulsed Laser Storage Toshiba Compact Klystron Compact and reliable Multi-beam Klystron R&D High power RF Main Institute KEK SC RF Accelerator development システム構築・運転、性能測定 若手教育 ATF, STF 31

32 32 Item20082009201020112012 S. Cavity Development ($1.5M/year), HRF + Cly ($0.8M/year) Upgrade of SC Cavity performance Compact RF power source system Control system for SCRF Construction of Test Accelerator ・ Confirm the performance Electron Source ($0.5M/year) High Q and long life photo-cathode 500 kV DC High Voltage High Intensity Beam Generation Pulsed Laser Storage System ($0.4M/year) X-ray Detector ($0.1M/year) Design and R&D on laser storage X-ray Detector Annual Schedule and Budget 32

33 33 溶液中の化学反応、 タンパク質の機能、 衝撃破壊、 光誘起相転移 Impact by Compact High Brightness Photon Beam 1) 第 2 世代放射光源の性能が 実験室へ! 2) サブピコ秒 X 線源を 実験室へ! → 高速過渡現象の研究 3 ) 放射性廃棄物中の同位体検出 (エネルギー・環境問題解決へ) 構造ゲノム解析 @ A 大学 ナノマテリアル評価 @ B 企業研究所 高精細 X 線イメージング @ C 病院 33

34 34 technologyPresent statusTargetKey points Electron source 300 nC/pulse 10,000nC/pulse (2008-2009) 48,000 nC/pulse (2010-2012) Pulse laser, new photo- cathode 1 msec pulse length SC CavityPulse: 25 MV/m CW: 12 MV/m Pulse: 30 MV/m CW: 20 MV/m 無欠陥・清浄表面、 高精度電子ビーム溶接、 高精度成形、 無欠陥材料 Pulsed laser storage 0.5 mJ/pulse, Waist: 30  m 50 mJ/pulse, Waist: 8  m 4-mirror optical cavity Colliding control  m beam orbit control Sub-  m beam orbit control 環境の安定化、 高速フィードバック制御。 Target of component technology 34

35 35 Quantum beam project(2008-2012) a pproved by MEXT Compact high brightness X-ray source using SC Cavity 35 Photo-cathode RF Gun Pulsed Laser storage Cavity 30 MeV/m SC. 9 cell Cavity Decelerating Exp. X-ray Detector ERL R&D 25 MeV まで加速 decelerate to 1MeV He refrigerator


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