Electron Positron Injector Linac Status Kazuro Furukawa kazuro

Electron / Positron Injector Linac Status Kazuro Furukawa <kazuro. furukawa@kek. jp> for Linac division Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013.

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 u. Linac challenges v. Low emittance e- Low-emittance beam from Linac ( Higher Linac beam current) 40 x Luminosity ³ with high-charge RF-gun v. Low emittance e+ ³ with damping ring v. Higher e+ beam current e+ efficiency ³ with new capture section v. Emittance preservation ³ with precise beam control v 4+1 ring simultaneous injection Linac Upgrade Status towards Super. KEKB 2 x beam current RF-gun K. Furukawa, KEK, Mar. 2013. 2

Linac Facility Upgrade Ohsawa et al. u Addition of electric power and cooling water is crucial for the upgrade v However, the facility division starts the design only after the budget is secured v It was only approved in JFY 2012 (the facility budget is different from the project one) u Basic schedule v Design JFY 2012, Building JFY 2013, Facility JFY 2014 v Should not affect PF and PF-AR operation v Not available during initial commissioning high current gun low emittance RF gun 3. 5 Ge. V 10 n. C x 2 (prim. e-) 5 n. C x 2 (inj. e-) Bunch Compressor S-band linac e+ target & capture section Positron capture section 920 k. VA, 900 lit/min Linac Upgrade Status towards Super. KEKB 1. 1 Ge. V Damping Ring circ. 136 m Energy-spread Compression System 3 T RF gun 50 Hz (e+ or e-) pulse-by-pulse mode switching PF 2. 5 Ge. V e 0. 1 n. C x 1 LER PF-AR 6. 5 Ge. V e- 4. 0 Ge. V e+ 4 n. C x 2 ECS C-band modules Damping ring BT (LTR, RTL) 310 k. VA HER 7. 0 Ge. V e 5 n. C x 2 Switch yard (3 SY) 300 k. VA, 460 lit/min K. Furukawa, KEK, Mar. 2013. 3

Girder Recovery and Alignment u Re-constructing soft-structure girder into hard-structure u Alignment with Higo et al. v 120 m and 480 m long-baseline laser between girders v Laser tracker within a girder (~20 m) v Beam-based tests v Target: 0. 1 mm local / 0. 3 mm global alignment (from beam dynamics simulation) ³ Several iterations necessary for low-emittance beam transport u Beam transport/acceleration test for 600 m (Nov. 2012) v For the first time after the earthquake X Y Charge Girder Distortion Girder Reinforcement Linac Upgrade Status towards Super. KEKB Beam along 600 -m linac K. Furukawa, KEK, Mar. 2013. 4

Microwave Power Source Upgrade u. Pulsed power modulators Michizono et al. v. Nine compact modulators are introduced v. Share the same basic design for klystron, flux concentrator, and gun high voltage u. Fast LLRF controllers, power amplifiers, and LLRF monitors v. For simultaneous injection and bucket selection v. Pulse-to-pulse stability monitor v 50 Hz event-based synchronized controls Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 5

RF Gun for Low-emittance Electron Beam RF Gun Development Yoshida et al. u Photo cathode : stability, longer life, efficiency Ir 5 Ce v. At first La. B 6, then Ir 5 Ce 5 n. C / bunch u Laser : higher power, temporal profile control v. Nd: YAG medium, LD excitation ~1. 5 m. J / 30 ps / pulse at 266 nm v. Polarization control for slant irradiation v. Yb: YAG fiber laser is introduced u Cavity : better focusing field, higher gradient v. DAW (Disk and washer) type cavity DAW v. Development of quasi-travelling-wave side-coupled cavity as well u Test stands v. RFgun at A-1 is constructed with fiber laser for Super. KEKB v. RFgun at 3 -2 was used to inject into PF with proper synchronization v. Long-period demonstration will be performed Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 6

Beam Acceleration Test (RF-gun) u. Step-by-step beam tests v 4. 5 n. C 240 m acceleration v. Fiber-laser-based RF-gun X Y Charge Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 7

Positron Capture for High-current Positron Capture Section Development u Flux concentrator (FC) Kamitani et al. v Collaborations with BINP, IHEP and SLAC v Finalized optimization of field and mechanical design v Fabricated 1 st version of 2 nd generation, being tested u Large-aperture S-band (LAS) cavity structure v Positron capture tracking simulation FC v L-band structure as backup with co-linear load u Magnet design and fabrication v Solenoid and pulsed steering and quad magnet system u Reliability v Strategy for failed component replacement with detachable girder, etc LAS v Acceleration gradient distribution and optimization with backups Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 8

Beam Monitors: BPM and WS Suwada et al. ³ Limited performance with present 8 -bit 10 GS/s digitizers (oscilloscopes) u New BPM readout for precise orbit/emittance controls v. Fast attenuator for 0. 1 -10 n. C (Super. KEKB, PFAR) dynamic range v. Helical BSF (300 MHz) for 2 -bunch (96 ns apart) readout v 16 bit 250 MS/s ADC, FPGA data processing v 50 Hz event-control synchronization u. New wire scanner readout was also developed Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 9

Dual-layer Controls Single Machine, Multiple Virtual Accelerators (VAs) u Simultaneous injection, one of the VAs is active at a time u Independent parameter set for each VA, ~200 parameters are switched every 20 ms pulse e− Gun ARC PF Injection e– (2. 5 Ge. V) e− Gun KEKB-LER Injection ARC Primary e– (3. 5 Ge. V) Event-based Control System e+ (4 Ge. V) e+ Target e− Gun ARC KEKB-HER Injection e– (7 Ge. V) e− Gun ARC Linac Upgrade Status towards Super. KEKB PF-AR Injection e– (6. 5 Ge. V) K. Furukawa, KEK, Mar. 2013. 10

Dual-layer Controls Example of Beam Mode Pattern : e+ 25 Hz / e– 25 Hz u Interleaved e+ and e-, dependency between pulses mostly decoupled u With bucket selection at the both DR and MR e− Gun ARC Primary e– (3. 5 Ge. V) e+ (4 Ge. V) e+ Target 20 ms e− Gun ARC e– (7 Ge. V) 20 ms e− Gun ARC Primary e– (3. 5 Ge. V) e+ (4 Ge. V) e+ Target 20 ms e− Gun ARC e– (7 Ge. V) Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 11

u Preliminary Beam Tests in Autumn 2012 v Beam test along 600 -m Linac v for the first time after the earthquake v Latter half was tuned for PF/PFAR injection v Alignment will be recovered by 2014 X Y Charge v For energy spread optimization v Longitudinal beam profile management by photo-cathode RF-gun (30 ps square shape) v and bunch compression at the middle of linac are crucial Beam along 600 -m linac R 56=0 ³ Preliminary R 56 control was performed ³ Design and measurement of dispersion function with R 56=0 and R 56=-0. 6 Design Linac Upgrade Status towards Super. KEKB Measurement K. Furukawa, KEK, Mar. 2013. 12

Schedule u Winter 2013 : DR switchyard / DR tunnel construction u Spring 2013 : A 1 -RF-gun, Alignment u Summer 2013 : Installation of many components v. ECS, FC (gen. 2), DC solenoids, Klystron modulators, WS, etc u Autumn 2013 : e– then e+ commissioning (limited current) v. Half Linac: PF injection, Day: construction, Night: commissioning u Spring 2014 : Pulsed steering, Alignment u Summer 2014 : Installation of additional components v. Cooling water, FC (gen. 3), BPM, Pulsed magnets, New PFAR BT, etc u Autumn 2014 : Linac Full Commissioning u Winter 2015 : MR (then DR) injection commissioning u… Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 13

Summary u Much progress in disaster recovery and construction u Development for T=0 (~1 n. C) was mostly completed u Development for full spec. will be tested u Many development items are connected with beam emittance and energy spread management u Still expecting many challenging items to overcome u Injector should start at first ! u With some Phronesis (Greek: practical wisdom, ability to understand the universal truth), we believe we can achieve the target Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 14

Thank you Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 15

Review 2013 and Reviewer’s Comments (preliminary) u Overview of Injector Construction Status and Schedule v The Linac Group setup prioritized work scopes with back-up options. The overall scheme is very logical, and the committee is convinced by their near term plan. u RF gun v Install and test the QTWSC gun as planned. Operate it for a long period to check its reliability and performance stability. u Alignment and Support v The Linac alignment and support is less mature. There should be some effort to accelerate this to avoid the possibility of impacting commissioning. u Positron Source v The target size should fit into the available space between the yoke and flux concentrator. The discharge waveform of the modulator for the flux concentrator with cables should be checked experimentally. u Commissioning (of Electron Beam) v After identifying the parameters that the linac electron beam needs to meet, a detailed set of procedures should be made for each parameter. An overall time schedule to carry out these procedures should be developed to match times needed by the four rings. Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 16

Review Items in 2012 and Reviewer’s Comments u Linac disaster recovery v. Earthquake is a natural disaster, a Force Majeure. In view of the manpower shortage in the Linac and Storage Ring groups, the committee suggests that the management team look into timeline, milestones and resources, and revise the schedule accordingly. u RF gun and low-emittance transport v. Aggressively pursue a demonstration of the QTW gun with La. B 6 cathode and the full power laser. u Positron source v. CSR effects in the bunch compressor should be examined. A protection scheme for the target should be developed at least conceptually. Linac Upgrade Status towards Super. KEKB K. Furukawa, KEK, Mar. 2013. 17

Linac Overview Linac Upgrade for Super. KEKB u Higher Injection Beam Current v To Meet the larger stored beam current and shorter beam lifetime in the ring v 4~8 -times larger bunch current for electron and positron u Lower-emittance Injection Beam v To meet nano-beam scheme in the ring v Positron with a damping ring, Electron with a photo-cathode RF gun v Emittance preservation by alignment and beam instrumentation u Quasi-simultaneous injections into 4 storage rings v Super. KEKB e–/e+ rings, and light sources of PF and PF-AR v Improvements to beam instrumentation, low-level RF, controls, timing, etc Super. KEKB injector Linac high current gun low emittance RF gun 3. 5 Ge. V 10 n. C x 2 (prim. e-) 5 n. C x 2 (inj. e-) Bunch Compressor S-band linac e+ target & capture section Linac Upgrade Status towards Super. KEKB 1. 1 Ge. V Damping Ring circ. 136 m Energy-spread Compression System 3 T RF gun 50 Hz (e+ or e-) pulse-by-pulse mode switching PF 2. 5 Ge. V e 0. 1 n. C x 1 LER PF-AR 6. 5 Ge. V e- 4. 0 Ge. V e+ 4 n. C x 2 ECS C-band modules HER 7. 0 Ge. V e 5 n. C x 2 K. Furukawa, KEK, Mar. 2013. 18

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 4 5 PF-AR 6. 5 Ge. V 5 n. C LER 4. 0 Ge. V e+ 4 n. C x 2 HER 7. 0 Ge. V 5 n. C x 2 20 um u As a high-field (several Tesla) pulsed solenoid for the positron source of the Super. KEKB injector, KEK is going to fabricate a SLAC-type flux concentrator. u Technical advices from the IHEP experts and design information by the IHEP drawings are quite useful in the development. Flux Concentrator electron beam Linac Upgrade Status towards Super. KEKB positron beam K. Furukawa, KEK, Mar. 2013.