Injector Linac Kazuro Furukawa for Injector Linac Upgrade

Injector Linac Kazuro Furukawa for Injector Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 1

Thanks to the reviewers Dr. Tsumoru Shintake, OIST, chair Dr. Matt Poelker, JLAB Dr. Sasha Gilevich, SLAC Dr. Yosuke Honda, c. ERL/KEK Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 2

Linac Overview Mission of electron/positron Injector in Super. KEKB u 40 -times higher Luminosity v. Twice larger storage beam Higher beam current at Linac v 20 -times higher collision rate with nano-beam scheme ³ Low-emittance even at first turn ³ Shorter storage lifetime Low-emittance beam from Linac Higher Linac beam current u. Linac challenges v. Low emittance e³ with high-charge RF-gun v. Low emittance e+ ³ with damping ring v. Higher e+ beam current ³ with new capture section v. Emittance preservation ³ with precise beam control v 4+1 ring simultaneous injection Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 3

Linac Upgrade for Super. KEKB PF B A J-arc 1. 5 Ge. V Primary e– for e+ 3. 2 Ge. V, 10 n. C x 2 Bunch Compression C 1 Bunch Compression New e+ Capture with FC 2 2. 5 Ge. V 0. 1 n. C x 1 1. 1 Ge. V e+ damping ring New RF-gun 5 n. C for e–, 10 n. C for e+ Ir. Ce cathode, Fiber laser, DAW cavity SY 2 Energy Compression 3 Energy SY 3 Compression 5 4 LER 4. 0 Ge. V e+ 4 n. C x 2 HER PF-AR 7. 0 Ge. V 5 n. C x 2 20 um 6. 5 Ge. V 5 n. C u Low emittance RF-gun development v Photo-cathode: stability, long-lifetime, quantum efficiency Ir 5 Ce ³ La. B 6, Ir 5 Ce and other possibilities, 5 n. C/bunch achieved v Laser : high-power, stability, bunch profile management ³ Nd: YAG media, LD excitation, 1. 5 m. J / 30 ps achieved ³ Fiber laser development for profile control v Cavity : field optimization ³ Disk and washer (DAW) cavity ³ Quasi traveling-wave (QTWSC) cavity DAW v Operation : higher stability and reliability ³ PF injection was tested, longer-term tests, backups, are planned Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 4

Linac Upgrade Progress towards Super. KEKB u High-charge low-emittance RF gun development Quasi traveling wave side couple cavity v. QTWSC cavity and Ir 5 Ce photo cathode works well Ir 5 Ce Cathode u Positron generation confirmation for the first time v. Good agreement with the simulation results Positron generator Signal from primary electron Signal from positron with opposite polarity u Precise alignment for emittance preservation v. Recovering after earthquake v. Reaching specification of 0. 2 mm u Utility upgrade during summer 2014 v for electricity (+1. 5 MW) and cooling water (+1400 L/min) Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 5

Schedule Linac Schedule Overview RF-Gun e- beam commissioning at A, B-sector e- commiss. at A, B, J, C, 1 e+ commiss. at 1, 2 sector (FC, DCS, Qe- 50%) e- commiss. at 1, 2, 3, 4, 5 sector Phase 1: high emittance beam for vacuum scrub Phase 2, 3: low emittance beam for collision Time → Location ↓ 1 n. C Phase 1 : Electron : Positron : Low current electron Linac Upgrade towards Super. KEKB non damped e+ commiss. at 1, 2, 3, 4, 5 sectors e- commiss. at A→ 5 sectors 2 n. C Phase 2 damped e+ commiss. at 1→ 5 Qe+ = 1~4 n. C e- commiss. at A→ 5 Qe- = 1~5 n. C K. Furukawa, KEK, RF-gun review, Feb. 2015. 6

Alignment u High-precision alignment was not necessary in PF and KEKB injections, and it was much damaged by earthquake in 2011. u Instead of flexible-structure girder before earthquake, rigid-structure was adopted with jack-volts and fixed supports. u Reflector pedestals are developed and mounted onto quad magnets and accelerating cavities for laser-tracker measurement. u Iterative measurement and adjustment with 500 -m straight laser and position sensors should enable 0. 3 -mm global alignment. u Laser tracker should enable 0. 1 -mm measurement within 10 -m girder unit. u Displacement gauges, hydrostatic leveling, inclinometer are also employed. u Remote measurement system and girder mover system will be necessary for longer term, and are under development. Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 7

Alignment progress in 2014 u For the first time at 3 -5 sectors u Horizontal axis: sensor number from sector C, 1 -4, to sector 5 (~80 m/sector) u Vertical axis: voltage (~displacement at 0. 25~0. 5 mm/m. V) u Some girders were not yet upgraded u Moved up to 3 mm not to break vaccuum Displacement / m. V Sector C Linac Upgrade towards Super. KEKB Sector 5 K. Furukawa, KEK, RF-gun review, Feb. 2015. 8

Alignment progress in 2014 u For the first time after earthquake at downstream sectors u Several measurements during summer u Measurement reproducibility was confirmed up to ~0. 2 mm u While there existed several conflicting measurements, consistent scheme ~5 mm has been established u Movement of tunnel by several 10’s of micrometer was observed (→ mover) ~10 mm u Further work necessary in 2015, for alignment and girder replacement Linac Upgrade towards Super. KEKB Higo et al. K. Furukawa, KEK, RF-gun review, Feb. 2015. 9

Positron Enhancement Positron Generation u 4 -times more positron is required at Super. KEKB than KEKB v. Safety measure was taken after cable fire during the test of Flux Concentrator (FC) v. New components in 100 -m capture section were tested in steps v. High voltage tests in tunnel in April v. Beam tests with electron in May Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 10

11 Positron Enhancement Positron generation for Super. KEKB bridge coils side view 10 n. C primary e- DC QM spoiler solenoid LAS Accel. structure target primary e- beam e+ beam hole positron 5 n. C injection e- production Target Flux Concentrator pulsed ST pulsed QM Flux Concentrator Bridge Coils New positron capture section after target with Flux concentrator (FC) and large-aperture S-band structure (LAS) Satellite bunch (beam loss) elimination with velocity bunching Pinhole (2 mm) for electrons beside target (3. 5 mm) Beam spoiler for target protection Linac Upgrade towards Super. KEKB e+ beam K. Furukawa, KEK, RF-gun review, Feb. 2015. 11

Positron Enhancement T. Kamitani Positron Generation 1) Installation of positron generator for Super. KEKB in April 2014 (Beamline construction since summer 2013) (positron target, spoiler, Flux Concentrator, bridge coils, LAS structures [x 6], DC solenoids [16+13], e+/e- separator, quads [>90]) 2) Commissioning of positron beam, observation of the first positron after reconstruction for Super. KEKB, further improvements expected Primary e- [n. C] Positron [n. C] Efficiency Parameters 0. 6 0. 12 20% FC 6. 4 k. A, Solenoids 370 A, LAS capture field 10 MV/m June 2014 Specification (at SY 2) DR injection (2017? ) 3) x 17 10. 0 5. 0 4. 0 x 42 50% 40% x 2. 5 FC 12 k. A, Solenoids 650 A, LAS capture field 14 MV/m Energy spread acceptance 0. 5% Oct. ~Dec. 2014 : Linac commissioning Jan. ~May. 2015 : Construction Jun. : Linac commissioning Jul. ~Sep. 2015 : Construction Oct. ~Jan. 2016 : Linac commissioning Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015.

RF gun for low-emittance electron RF-Gun development strategy for Super. KEKB u Cavity : Strong electric field focusing structure v. Disk And Washer (DAW) => 3 -2, A-1(test) v. Quasi Traveling Wave Side Couple => A-1 => Reduce beam divergence and projected emittance dilution u Cathode : Long term stable cathode v. Middle QE (QE=10 -4～ 10 -3 @266 nm) v. Solid material (no thin film) => Metal composite cathode => Started from La. B 6 (short life time) => Ir 5 Ce has very long life time and QE>10 -4 @266 nm u Laser : Stable laser with temporal manipulation v. LD pumped laser medium => Nd / Yb doped v. Temporal manipulation => Yb doped => Minimum energy spread Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015.

RF gun for low-emittance electron Beam tracking simulation result 5 n. C Gun Exit Emittance 5. 5 mmmrad M. Yoshida 10 n. C Size 0. 4 mm Energy spread 0. 6% Bunch shape Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015.

RF gun for low-emittance electron Energy spread reduction using temporal manipulation M. Yoshida Energy spread of 0. 1% is required for Super. KEKB synchrotron injection. 15 n. C t 5 n. C 10 n. C 20 n. C Gaussian t Square 5 n. C electron Linac Upgrade towards Super. KEKB 5 n. C 10 n. C 15 n. C 20 n. C 15 n. C Primary beam for positron production K. Furukawa, KEK, RF-gun review, Feb. 2015. 15

RF gun for low-emittance electron Photo cathode RF gun development Cascaded frequency doublers Yb fiber and Yb: YAG think disk laser Ir 5 Ce photo cathode Linac Upgrade towards Super. KEKB Quasi traveling wave side couple Partcavity of multi-pass Amplifier u 5. 6 n. C / bunch was confirmed u Next step: 50 -Hz beam generation & Radiation control K. Furukawa, KEK, RF-gun review, Feb. 2015. 16

RF gun for low-emittance electron GU_A 1 Laser Configuration as of Dec. 2014 Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 17

RF gun for low-emittance electron Photo cathode RF gun improvement u. Crucial for high-current low-emmittance beam u. New Ir 5 Ce cathode and new cavity QTWSC were successful u. Basic features were confirmed at 2 ~ 5 Hz u. Expect beam parameter and stability performance at 50 Hz, with multi-pass amplifiers and cooling system u. Resolved the issue of oscillator synchronization u. Staged laser system improvements with beam measurement system Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 18

Commissioning R 0 ARC Dispersion: need for investigation u Measurement (dot) compared with expected value (line) Preliminary R 16 R 36 Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 19

Electron gun rearrangement Towards the injection u. We didn’t completed the preparation of routine injection beam for Phase-1 u. We prepare for routine operation while continueing the development vex. Thermionic gun u. Also considering the schedule for radiation control licenses v. Mar. -Jun. 2015, Jun. -Oct. 2015 u. Need balance between development, operation, schedule, and budget Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 20

Electron gun rearrangement Staged Radiation Control License towards Super. KEKB u. Two licenses were approved in June 2014 u[1] Beam diagnostic station at #A 2 just after gun vfor 1250 n. C/s at 50 Hz 2 bunches u[2] Beam dump at #28 just before damping ring vfor 10 n. C/s with positrons u. Radiation measurements especially at positron generator v. Indispensable to estimate radiation at >100 times higher beam u. Both approved u. Soon apply for the next license at ~Jun. 2015 Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 21

Electron gun rearrangement Up to Dec. 2014. KL-A 1 -B KL-A 1 -A Cavities Linac Upgrade towards Super. KEKB Phase shifters RF-gun K. Furukawa, KEK, RF-gun review, Feb. 2015.

Installation of Thermionic Gun u. Under construction v. Jan. 2015 – May. 2015. Thermionic gun RF gun Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 23

KEKB Injector Division Group Structure u Microwave (RF): klystron, pulse-modulator, llrf, (at linac, c. ERL, STF) u Accelerator: structure/cavity, vacuum, magnet, alignment, cooling water, (devices in tunnel), etc u Controls: computer controls, beam monitors, timing, alignment, etc u Injector: RF-gun, beam monitor, pulsed devices, etc v. M. Yoshida, X. Zhou, T. Natsui, R. Zhang, (D. Satoh), … u Operation: operation management, safety, etc v. Routine/basic operation: out-sourced u Commissioning: traversal group between groups Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 24

Schedule Linac Schedule Overview RF-Gun e- beam commissioning at A, B-sector e- commiss. at A, B, J, C, 1 e+ commiss. at 1, 2 sector (FC, DCS, Qe- 50%) e- commiss. at 1, 2, 3, 4, 5 sector Phase 1: high emittance beam for vacuum scrub Phase 2, 3: low emittance beam for collision Time → Location ↓ 1 n. C Phase 1 : Electron : Positron : Low current electron Linac Upgrade towards Super. KEKB non damped e+ commiss. at 1, 2, 3, 4, 5 sectors e- commiss. at A→ 5 sectors 2 n. C Phase 2 damped e+ commiss. at 1→ 5 Qe+ = 1~4 n. C e- commiss. at A→ 5 Qe- = 1~5 n. C K. Furukawa, KEK, RF-gun review, Feb. 2015. 25

Alignment Injector linac schedule and RF-gun u Feb(? ). 2015 – Jun(? ). 2015: Phase-1 commissioning v Non-low-emittance, 1 n. C electron/positron beams, without damping ring (DR) ³ With combination of RF-gun and thermionic gun ³ ex. Electron with 1 n. C RF-gun, Positron with 6 n. C (? ) thermionic gun w (depends on downstream configuration after DR delay affecting PF/PF-AR injections) u Dec(? ). 2016 – May(? ). 2017, Damping ring commissioning v 1 n. C – 2 n. C positron beam, to/from DR u Jun(? ). 2017 – Feb(? ). 2018, Phase-2 commissioning v Low-emittance (20 mm. mrad, 0. 1%), 2 n. C electron/positron beams, with DR ³ Low-emittance electron beam with RF-gun, 2 n. C ³ Primary beam for positron with RF-gun or thermionic gun, 5 n. C u Oct(? ). 2018 – …, Phase-3 commissioning v Low-emittance (20 mm. mrad, 0. 1%), 4 n. C electron/positron beams, with DR ³ Low-emittance electron beam with RF-gun, 4 n. C ³ Primary beam for positron with RF-gun or thermionic gun, 10 n. C Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 26

Summary u. Steady progress towards first MR injection u. Finishing earthquake disaster recovery in FY 2014 u. Will make staged improvements before 2018 u. Will balance between final beam quality and staged operation u. Will select optimized route depending on available resources v. Incorporate thermionic gun as well as RF gun Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 27

Mt. Tsukuba Thank you Super. KEKB dual rings PF-AR PF Linac Upgrade towards Super. KEKB Injector Linac K. Furukawa, KEK, RF-gun review, Feb. 2015. 28

Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 29

Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 30

Pulse-to-pulse modulation u Four PPM virtual accelerators for Super. KEKB project maybe with additional PPM VAs for stealth beam measurements based on Dual-tier controls with EPICS and event-system Event-based Control System Every 20 ms F. B e− Gun ARC PF Injection e– (2. 5 Ge. V, 0. 2 n. C) F. B e− Gun ARC Damping ring Super. KEKB-LER Injection F. B e– (3. 5 Ge. V, 10 n. C) F. B e+ Target e+ (4 Ge. V, 4 n. C) e− Gun ARC Super. KEKB-HER Injection F. B e– (7 Ge. V, 5 n. C) e− ARC F. B Gun PF-AR Injection F. B e– (6. 5 Ge. V, 5 n. C) Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 33

Linac Upgrade towards Super. KEKB K. Furukawa, KEK, RF-gun review, Feb. 2015. 34