Progress of Injector Linac Kazuro Furukawa for Injector

Progress of Injector Linac Kazuro Furukawa for Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 1

Linac Upgrade 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 Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 2

Required beam parameters Stage KEKB Phase-I Super. KEKB Item e+ e- Energy 3. 5 Ge. V 8. 0 Ge. V 4. 0 Ge. V 7. 0 Ge. V Primary e 4 n. C 1 n. C Bunch charge Primary e 10 n. C → 1 1 n. C → 0. 2 n. C Primary e-10 n. C → 4 n. C 5 n. C Norm. Emittance (g e) (mrad) 2100 2400 150 100/20 (Hor. /Ver. ) 50/20 (Hor. /Ver. ) Energy spread 0. 125% ± 0. 5% 0. 1% Num. of Bunch / Pulse 2 2 2 Repetition rate 50 Hz Simultaneous top-up injection 3 rings (KEKB e-/e+, PF) Injector Linac Progress towards Super. KEKB 50 Hz No top-up 4 rings (Super. KEKB e-/e+, PF-AR) K. Furukawa, KEK, Nov. 2015. 3

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 ↓ Step-by-step Licenses Low Emittance Beams 4+1 Ring Injections DR Commiss. 1 n. C Phase 1 Without Top-up : Electron : Positron : Low current electron Injector Linac Progress 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 4 n. C Phase 3 Direct PF-AR BT damped e+ commiss. at 1→ 5 Qe+ = 1~4 n. C e- commiss. at A→ 5 Qe- = 1~5 n. C Improved RF gun K. Furukawa, KEK, Nov. 2015. 4

Super. KEKB master schedule ・・・ JFY 2010 JFY 2011 JFY 2012 JFY 2013 JFY 2014 JFY 2015 JFY 2016 JFY 2017 ・・・ Now (Nov, 2015) KEKB operation Dismantle KEKB Phase 2 commissioning： l Squeezing beta at IP l Beam collision tuning l Start physics data taking Super. KEKB upgrade construction Phase 3： l Physics run with full Belle II with VXD Startup, conditioning, etc. Phase 2、3 Phase 1 commissioning： l Basic machine tuning l Low emittance beam tuning l Vacuum scrabbing Super. KEKB operation DR About 10 years Akai, Jun. 2015. Injector Linac Progress towards Super. KEKB DR commissioning starts prior to Phase 2 Belle II install, QCS install K. Furukawa, KEK, Nov. 2015. 5

Subjects to Consider u Too many subjects ! u Phronesis needed (Greek: Practical wisdom, Ability to understand the Universal Truth) Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 6

Linac Upgrade Overview Linac Upgrade Progress towards Super. KEKB (1) u High-charge low-emittance RF gun development v. QTWSC cavity and Ir 5 Ce photo cathode developments Quasi traveling wave side couple cavity Ir 5 Ce Cathode u Positron generator commissioning 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. 3 mm u Utility upgrade during FY 2014 v for electricity (+1. 5 MW) and cooling water (+1400 L/min) Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 7

Linac Upgrade Overview Linac Upgrade Progress towards Super. KEKB (2) u High power modulator upgrades u Low-level RF controls/monitor v Pulse-to-pulse modulation (PPM) between 4+1 rings v More spaces for increased number of devices u Beam instrumentation v Large/small aperture beam position monitors (BPM) v Precise/fast and synchronized BPM readout system v Wire scanners and beam loss monitors v Streak cameras v (Deflectors, etc) u Event timing control system v Combination of MRF & SINAP modules v Essential for PPM operation v Precise timing & synchronized controls v Bucket selection at DR and MR SINAP event modules Injector Linac Progress towards Super. KEKB Beam wire scanner K. Furukawa, KEK, Nov. 2015. 8

Recent works Recent Works Positron generator at #15 region Iron shield Positron generator complex Thermionic gun at #A 1 region Thermionic gun for high-current beam RF gun for low-emittance beam Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 9

Thermionic Gun Preparation of Thermionic Gun u Refurbished v Raise by 75 cm not to conflict with straight RF-gun ³ As well as angled RF-gun v ~ Jun. 2015. u May serve v electrons in phase-I v primary electron for positron generation in phase-II and later Thermionic gun RF gun Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 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 e+ beam hole 5 n. C injection primary e- beam positron 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 passing electrons beside target (3. 5 mm) Recently, facing discharge difficulties at maximum field Injector Linac Progress towards Super. KEKB e+ beam K. Furukawa, KEK, Nov. 2015. 11

Schedule Radiation protection licenses u Step-by-step upgrade of beam limits u Final goal is 1250/625 n. A before/after target v. Same as KEKB u Applications v. Fall. 2013. 10 n. A at #28 dump, 1250 n. A at #A 2 dump v. Spring 2014. New utility rooms, 50 n. A at #61 straight dump v. Jun. 2015. 200 n. A at #15 target v. Early 2016. (? ) 800 n. A at #15 target, 625 n. A at #61 v. Sometime 2016. (? ) 1250 n. A at #15 target u Shield, shield, shield … Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 12

Summary u Steady progress towards first MR injection in FY 2015 u Finished earthquake disaster recovery in 2014 u Will make step-by-step improvements up to Phase-III u Alignment: almost confident on the required precision (0. 1 -mm local, 0. 3 -mm global), need to maintain for longer term u Positron generator: another license test, need discharge analysis u Thermionic gun: re-commissioned, working u RF gun: following recommendations at review meetings u Need much more radiation shield u Will balance between final beam quality and progressive operation u Will select optimized route depending on available resources u With some Phronesis we may enjoy coming beam commissioning Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 13

Mt. Tsukuba Thank you Super. KEKB dual rings PF-AR PF Injector Linac Progress towards Super. KEKB 600 m Injector Linac K. Furukawa, KEK, Nov. 2015. 14

Injector Linac Progress towards Super. KEKB K. Furukawa, KEK, Nov. 2015. 15