Electron Positron Injector Linac Kazuro Furukawa for Injector

Electron / Positron Injector Linac Kazuro Furukawa for Injector Linac group Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

Linac Overview Super. KEKB での Linac の役割 u 40 -times higher Luminosity v. Twice larger storage beam Higher Linac beam current v 20 -times higher collision rate with nano-beam scheme ³ Low-emittance Linac injection beam ³ Shorter storage lifetime Higher Linac beam current u. Linac challenges v. Low emittance e³ High-charge RF-gun v. Low emittance e+ ³ Damping ring v. Higher e+ beam current ³ New capture section v. Beam transport ³ Emittance preservation v 4+1 ring simul. injection Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 2

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 (PPM) 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 & L-band+LAS 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 Ir 5 Ce FC 50 Hz (e+ or e-) pulse-by-pulse mode switching PF PF-AR LER 6. 5 Ge. V e- 2. 5 Ge. V e 0. 1 n. C x 1 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. F, KEK, Dec. 2013. 3

Linac Schedule Overview RF-Gun e- beam commissioning at A, B-sector Qe- = 5 n. C e- commiss. at A, B, J, C, 1 Qe- = 5 n. C e+ commiss. at 1, 2 Qe+ = 0. 5 n. C (FC, DCS, Qe- 50%) e- commiss. at 1, 2, 3, 4, 5 Qe- = 5 n. C 1 n. C : Electron : Positron : Low current electron Linac Upgrade Status towards Super. KEKB non damped e+ commiss. at 1, 2, 3, 4, 5 Qe+ = 4 n. C e- commiss. pulse-switch at A→ 5 Qe- = 5 n. C 2 n. C damped e+ commiss. at 1→ 5 Qe+ = 4 n. C e- commiss. at A→ 5 Qe- = 5 n. C 4 n. C PF-AR ecommiss. K. F, KEK, Dec. 2013. 4

Schedule 概略の予定 u 2013 夏: 多数の機器の設置 u 2013 秋: e– commissioning (limited) v後半部: PF 入射, 前半部 日中準夜: ビームコミッショニング u 2014 春: Commissioning 継続, 後半部調整, Alignment 等々 v後半部: PF 入射, 前半部 日中: DR 建設, 準夜: ビームコミッショニング u 2014 夏: 機器の設置, PFAR-BT (部分) v冷却水・電力増強, Pulsed magnets 設置, 安全系 u 2014 秋: Linac (nearly) full commissioning v. PF without daytime top-up? BPM (partially), RF-monitor u 2015 冬: MR then (春) DR injection commissioning v. Normal emittance, 1 n. C, Non-continuous injection, PF Top-up u 2016: MR commissioning v. Lower emittance, 2 n. C, Continuous injection Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 5

PF-AR 直接入射路 事 追加シールド Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 6

FC 開発 3 号機ぼや Cable 20 cm 焼損 Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 7

SLAC-Super. KEKB Workshop (Injector Linac) u Injector commissioning and issues 30' v Speaker: Masanori Satoh (KEK) u Photo-cathode RF gun 20' v Speaker: Takuya Natsui (KEK) u Positron source 30' v Speaker: Takuya Kamitani (KEK) u Timing synchronization 20' v Speaker: Hiroshi Kaji (KEK) u Linac alignment 20' v Speaker: Toshiyasu Higo (KEK) u Beam optics design for simultaneous injection 20' v Speaker: Takako Miura (KEK) Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 8

Questions and Answers u PEDD dependent on beam repetition? v SLAC study was on single-pulse energy density ³ may need further investigation u Fiber loss monitor blackening around target? v Can be replaced routinely u Diamond loss detector? v Is worth comparing in the future u Orbit stability tolerance against beam size? v Pinhole 2 mm and beam sigma 0. 3 mm are possible Beam orbit jitter will be studied, as well as for emittance preservation u Rotating target/spoiler? v Should be studied for the beam current larger u Frequency synchronization btw. linac/ring? v All SKEKB frequencies are generated from common freq. with ring circumference compensation u Beam charge variation pulse-pulse? v Can be important v Technically possible with different event assignment v Means different injection modes with different orbit stabilization for wakefield u Target quad – pulsed ? u Beam jitter should be small u DR extraction angle jitter v Offset injection position/angle jitter should be small Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 9

ビーム光学設計 u. Pulsed quad の追加 – 同時入射向け u. FODO → Doublet – Low emittance u. Orbit correction simulation u. Emittance preservation u予算の Optimize… Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 13

KEK e-/e+ Injector LINAC A B 1. 5 Ge. V e- C 10 n. C x 2 (for LER) 5 n. C x 2 (for HER) 0. 3 n. C x 1 (for AR) 0. 3 n. C x 1 (for PF) low emittance 1. 1 Ge. V RF gun 1 2 e+ target same energy DR 3 4 5 e-: Chicane 4. 219 Ge. V ee+ target l e-/e+ beams are delivered to 4 -rings with different current & energy. l Beam acceleration modes must be switched by 50 Hz pulse-by-pulse for top-up injection. Decelerate 1. 1 Ge. V e+ HER: 7 Ge. V e 5 n. C x 2 AR: 6. 5 Ge. V e 0. 3 n. C x 1 LER: 2. 5 Ge. V e+ 4 n. C x 2 PF: 2. 5 Ge. V e 0. 3 n. C x 1 1. 5 Ge. V C 1 2 3 4 5 Beam optics should satisfy the fast beam-mode switching. Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

Result of e-p fitting e- Linac Upgrade Status towards Super. KEKB e+ K. F, KEK, Dec. 2013.

Emittance Preservation u If Device is off center of the beam v. Focusing magnet (quad) kicks the beam bunch v. Accelerating structure (cavity) excites wakefield, to bend the tail u Distorted bunch in banana shape v. Emittance dilution or blow-up v. Depending on the beam optics and the beam charge u Orbit correction is crucial to preserve the emittance Sugimoto et al. Beam Focusing Magnet Accelerating Structure Transverse distribution in time direction Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 16

Emittance Dilution u. Offset injection may solve the issue u. Orbit have to be maintained precisely Mis-alignment leads to Emittance blow-up Orbit manipulation compensates it 100 samples Sugimoto et al. Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 17

Alignment Error vs. Emittance Growth <Tracking Condition> Calculated by H. Sugimoto • Positron is transported from DR outlet to LINAC end. • Alignment error is given in quads and cavities. • The orbit correction is performed by assuming the center of the quads and BPM are exactly the same. • Initial Emittance@Outlet of DR =6. 5 mm / 89 mm (Vertical / Horizontal) Vertical Horizontal Zoom e+ norm. at LINAC-end should be less than 20 m / 100 m ( Ver. / Hor. ) Linac Upgrade Status towards Super. KEKB l Triplet and doublet give almost same results. l In triplet and doublet, misalignment of 300 m is acceptable. l In FODO lattice, significant emittance growth is seen. K. F, KEK, Dec. 2013.

Positron Source u. High current positron is required u. Positron capturing with flux concentrator (FC) and large aperture s-band structure (LAS) u. Deceleration field to reduce satellite bunches u. Pinhole beside target for electron beam u. Protection system with beam spoilers Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 19

陽電子ビームライン建設 – SLED target +FC KLY 1 -5 LAS 14 MV/m deceleration & phase slip & acceleration SLED 捕獲部分 KLY 1 -6 LAS : Large Aperture S-band structure LAS 10 MV/m acceleration Solenoids l primary e- 3. 2 Ge. V, 10 n. C x 2 bunch, 50 Hz l tungsten target l AMD system (5. 0 T x 200 mm + 0. 4 T x 15 m) Flux Concentrator DC solenoids l KLY 1 2 m LAS x 2 (14 MV/m), aperture 2 a = 32 -> 30 mm (typical S-band ~20 mm) l KLY 2 2 m LAS x 4 (10 MV/m), aperture 2 a = 32 -> 30 mm Deceleration capture l e+ beam energy at capture section exit : 110 Me. V e+ yield: N(e+)/N(e-) = 49 % at 1. 1 Ge. V DR Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 20

Flux Concentrator Assembly FC assembly primary e- beam positron production Target quick detachable power & water connection to minimize worker's radiation dose Flux Concentrator Bridge Coils e+ beam Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 21

22 e+/e- beam switching at target side view 10 n. C primary e- bridge coils DC QM spoiler target rear view solenoid LAS Accel. structure target diameter 4. 0 mm target offset 3. 5 mm e+ beam hole 5 n. C injection e. Flux Concentrator pulse ST pulse QM 2. 0 mm FC offset hole diameter 2. 0 mm 7. 0 mm FC aperture Two possible schemes of beam switching by orbit bump 1) e+ on-axis, e- offset -> e- emittance growth by solenoid kick induced orbit 2) e- on-axis, e+ offset we take this scheme. -> e+ yield degradation (50% -> 10%) T. Kamitani Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

RF Gun GR_A 1 Overall Structure Regenerative Amplifier Oscillator Linac Upgrade Status towards Super. KEKB Multipass Amplifier K. F, KEK, Dec. 2013. 24

Regenerative Amplifier Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 25

Multipass Amplifier Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 26

Quadruple Frequency Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 27

Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 28

GR_A 1 : 5. 1 n. C / bunch Horizontal position /mm Vertical position /mm Charge /n. C Charge Trend / Stability Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

Beam Trend / Stability Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

Horizontal / Vertical stability Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

Dual-layer Controls Virtual Accelerator-based Controls u Multiple closed loops were installed on each PPM VA independently v Tested at KEKB e− Gun ARC e– BT (PF: 2. 5 Ge. V, 0. 1 n. C) PF Injection e+ Target e− Gun Event-based Control System ARC KEKB-LER Injection Primary e– (4 Ge. V, 10 n. C) e+ BT (KEKB: 3. 5 Ge. V, 0. 6 n. C) e+ Target e− Gun ARC KEKB-HER Injection e+ Target e– BT (KEKB: 8 Ge. V, 1. 2 n. C) Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013. 32

Event-based Control System u Four PPM VAs at least for Super. KEKB project Every 20 ms F. B (maybe with additional PPM VA for stealth beam) 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− Gun ARC F. B PF-AR Injection F. B e– (6. 5 Ge. V, 5 n. C) Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

System Construction Display and Analysis EPICS Controls Multiple Independent PPM Parameters Common Parameters Multiple Event Synchronous Controls PPM Virtual Accelerators Multiple Simulation Virtual Accelerators Real Accelerator Linac Upgrade Status towards Super. KEKB K. F, KEK, Dec. 2013.

Injector Commissioning Plan and Issues e- beam Bunch compression @ J-ARC BNS damping @ Sector A-B 20 mm mrad, 0. 08% energy spread, 5 n. C, two bunch Component Alignment & BBA e- RF gun (5 n. C) Offset injection @ Sector C-5 High precision monitor Uniform longitudinal beam distribution

Injector Commissioning Plan and Issues e+ beam Timing system /Bucket selection Damping ring operation Large aperture S-band structure 20 mm mrad, 0. 07% energy spread, 4 n. C, two bunch Component Alignment & BBA e- RF gun (10 n. C) Flux concentrator

Mt. Tsukuba Thank you Super. KEKB dual rings PF-AR PF Linac Upgrade Status towards Super. KEKB Injector Linac K. F, KEK, Dec. 2013. 38

ビームライン詳細 陽電子ター ゲットから LTR まで 地下と地上 の摺合わせ 各機器の最 終調整と発 注 Linac Upgrade Status towards Super. KEKB matching section e+ capture section K. F, KEK, Dec. 2013. 39