Electron / Positron Injector Linac
Kazuro Furukawa
for Injector Linac group

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

Linac Overview

SuperKEKB での Linac の役割! 40-times higher Luminosity"Twice larger storage beam
# Higher Linac beam current"20-times higher collision rate with nano-beam scheme$ # Low-emittance Linac injection beam
$ # Shorter storage lifetime# Higher Linac beam current!Linac challenges"Low emittance e$ High-charge RF-gun"Low emittance e+$ Damping ring"Higher e+ beam current$ New capture section"Beam transport$ Emittance preservation"4+1 ring simul. injection
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

2Linac Upgrade for SuperKEKB! Higher Injection Beam Current" To Meet the larger stored beam current and shorter beam lifetime in the ringIr5Ce
" 4~8-times larger bunch current for electron and positron! Lower-emittance Injection Beam" To meet nano-beam scheme in the ring
" Positron with a damping ring, Electron with a photo-cathode RF gun" Emittance preservation by alignment and beam instrumentation! Quasi-simultaneous injections into 4 storage rings (PPM)" SuperKEKB e–/e+ rings, and light sources of PF and PF-AR" Improvements to beam instrumentation, low-level RF, controls, timing, etc

SuperKEKB injector Linachigh currentgun
low emittanceRF gun

3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)Bunch
Compressor

S-bandlinac

e+ target &L-band+LAS
capture section
Linac Upgrade Status towards SuperKEKB

1.1 GeV
Damping Ringcirc. 136 m
Energy-spread
Compression System
3TRF gunFC50 Hz (e+ or e-)pulse-by-pulse
mode switching PFPF-ARLER 6.5 GeV e-

2.5 GeV e0.1nC x 1

4.0 GeV e+ 4nC x 2ECSC-bandmodules

HER 7.0 GeV e5nC x 2K.F, KEK, Dec.2013.

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RF-Gun e- beamcommissioning
at A,B-sector
Qe- = 5nC

Linac Schedule Overview
e- commiss.
at A,B,J,C,1
Qe- = 5nC

e+ commiss.
at 1,2 Qe+ = 0.5nC (FC, DCS, Qe- 50%)e- commiss.
at 1,2,3,4,5 Qe- = 5nC

1 nC: Electron: Positron: Low current electron

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non damped e+ commiss.
at 1,2, 3,4,5 Qe+ = 4nC
e- commiss. pulse-switch
at A→5 Qe- = 5nC

4 nC

2 nC

damped e+ commiss.
at 1→5 Qe+ = 4nCe- commiss.
at A→5 Qe- = 5nC

PF-AR ecommiss.

K.F, KEK, Dec.2013.

4Schedule

概略の予定! 2013 夏: 多数の機器の設置! 2013 秋: e– commissioning (limited)"後半部: PF 入射, 前半部 日中準夜: ビームコミッショニング! 2014 春: Commissioning 継続, 後半部調整, Alignment 等々"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! 2014 夏: 機器の設置, PFAR-BT (部分)

" 冷却水・電力増強, Pulsed magnets 設置, 安全系! 2014 秋: Linac (nearly) full commissioning"PF without daytime top-up? BPM (partially), RF-monitor! 2015 冬: MR then (春) DR injection commissioning" Normal emittance, 1nC, Non-continuous injection, PF Top-up! 2016: MR commissioning" Lower emittance, 2nC, Continuous injection
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

5

PF-AR 直接入射路工事 追加シールド

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

6

FC 開発 3 号機ぼや

Linac Upgrade Status towards SuperKEKB

Cable 20cm 焼損

K.F, KEK, Dec.2013.

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SLAC-SuperKEKB Workshop (Injector Linac)! Injector commissioning and issues 30'" Speaker: Masanori Satoh (KEK)! Photo-cathode RF gun 20'" Speaker: Takuya Natsui (KEK)! Positron source 30'" Speaker: Takuya Kamitani (KEK)! Timing synchronization 20'" Speaker: Hiroshi Kaji (KEK)! Linac alignment 20'" Speaker: Toshiyasu Higo (KEK)! Beam optics design for simultaneous injection 20'" Speaker: Takako Miura (KEK)

Linac Upgrade Status towards SuperKEKB

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8

Questions and Answers! PEDD dependent on beam repetition?
" SLAC study was on single-pulse energy density$ may need further investigation! Fiber loss monitor blackening around target?
" Can be replaced routinely! Diamond loss detector?
" Is worth comparing in the future! Orbit stability tolerance against beam size?
" Pinhole 2mm and beam sigma 0.3mm are possible
Beam orbit jitter will be studied, as well as for emittance preservation! Rotating target/spoiler?
" Should be studied for the beam current larger! Frequency synchronization btw. linac/ring?
" All SKEKB frequencies are generated from common freq. with ring circumference compensation! Beam charge variation pulse-pulse?
" Can be important" Technically possible with different event assignment" Means different injection modes with different orbit stabilization for wakefield! Target quad – pulsed ?
! Beam jitter should be small! DR extraction angle jitter" Offset injection position/angle jitter should be small
Linac Upgrade Status towards SuperKEKB

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9

BPM 読み出しの技術選択! Beam position monitor (BPM)"Emittance preservation に重要となる"~10µm の要求分解能 (現在の装置は 50~100µm)! Libera と SLAC の技術を基礎とした新規開発"それぞれ開発・評価中! SLAC の Steve Smith 氏と Andrew Young 氏に Review 依頼$ SLAC – SuperKEKB の協力の枠組み"Filter 設計、Dual-bunch 信号処理、System 設計に関して詳細なComment をもらう (may.22-27, jun.15-18.2013.)"Reviewer は新規開発を選択! 詳細設計の改善中"予算の関係で当初からの全数設置は避けるが、現在のところ、新規開発が性能、価格、運用、保守の全般で有利として、開発中

Linac Upgrade Status towards SuperKEKB

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10

Laser RF 電子銃 Workshop!ATF, cERL, Linac から計 16 人参加、6+ 件の発表
!機構内でも共通技術の交換の可能性がある!低 Emittance はほぼ共通目標であるが、Linacで重要な大電流 + 低エネルギー幅は Unique で、そのための技術交換はあまりなかった!安定度などについて、今後とも情報交換の予定!Web を準備する予定

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

11

LAS 加速管 Processing!陽電子捕獲のための大口径加速管"Large aperture S-band structure (LAS)!Processing に 1 ヶ月以上掛かっていることについて、識者意見を求め、22 人以上の多数の方の参加を得た (Dec.10.2013.)!時間が足りないと思われ、当面の試験運転対策、中期の改善対策について、議論が行われた"Interlock の改善、Baking は不要・無意味であること、RF monitor 等測定装置が重要であること、等助言を受けた

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

12

ビーム光学設計!Pulsed quad の追加 – 同時入射向け!FODO → Doublet – Low emittance!Orbit correction simulation!Emittance preservation!予算の Optimize…

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

13

KEK e-/e+ Injector LINAC
B

1.5 GeV e-C

10 nC x 2 (for LER)
5 nC x 2 (for HER)
0.3 nC x 1 (for AR)
0.3 nC x 1 (for PF) low emittance
1.1 GeV
RF gun

A

1

2

e+#target#

same3energyDR% e-/e+ beams are delivered to 4-rings withdifferent current & energy.
% Beam3accelera7on3modes3must3be3switched3by3
503Hz3pulseCbyCpulse3for3topCup3injec7on.

3

4

5

e(:Chicane

4.219#GeV#e-Decelerate

1.1 GeV

e+#target# e+

HER:373GeV3eC33
53nC3x2
AR:36.53GeV3eC
0.33nC3x1

LER:32.53GeV3e+
43nC3x2
PF:32.53GeV3eC
0.33nC3x1

1.5#GeV#C

1

2

3

4

5

Beam optics should satisfy the fast beam-mode switching.
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

Result of e-p fittingeC

Linac Upgrade Status towards SuperKEKB

e+

K.F, KEK, Dec.2013.

Emittance Preservation! If Device is off center of the beam" Focusing magnet (quad) kicks the beam bunch" Accelerating structure (cavity) excites wakefield, to bend the tail! Distorted bunch in banana shape" Emittance dilution or blow-up" Depending on the beam optics and the beam charge! Orbit correction is crucial to preserve the emittance
Sugimoto et al.

BeamFocusing
MagnetAcceleratingStructure
Transverse distribution in time direction

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

16

Emittance Dilution!Offset injection may solve the issue!Orbit have to be maintained precisely
Mis-alignment leads to Emittance blow-up

Orbit manipulation compensates it100 samples
Sugimoto et al.
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

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Alignment#Error#vs.#Emi>ance#Growth#<Tracking3Condi7on>
Calculated3by33H.3Sugimoto• Positron3is3transported3from3DR3outlet3to3LINAC3end.
• Alignment3error3is3given3in3quads3and3cavi7es.3• The3orbit3correc7on3is3performed3by3assuming3the3center3of3the3quads3and3BPM3are3exactly3the3same.3• Initial Emittance@Outlet of DR3=6.5 µm / 89 µm (Vertical / Horizontal)
Ver@cal
Horizontal

Zoom
e+3norm.3ε3at3LINACCend3should3be3less3than33203µm3/3100µm3(3Ver.3/3Hor.)

Linac Upgrade Status towards SuperKEKB% Triplet3and3doublet3give3almost3same3results.3% In3triplet3and3doublet,3misalignment3of3300µm3is3
acceptable.3% In3FODO3la`ce,3signiﬁcant3emibance3growth3is3seen.3
K.F, KEK, Dec.2013.

Positron Source!High current positron is required!Positron capturing with flux concentrator (FC)and large aperture s-band structure (LAS)!Deceleration field to reduce satellite bunches!Pinhole beside target for electron beam
!Protection system with beam spoilers

Linac Upgrade Status towards SuperKEKB

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19

陽電子ビームライン建設
SLEDtarget+FCKLY
1-5LAS 14 MV/mdeceleration & phase slip& acceleration

SLED–捕獲部分

KLY
1-6LAS : Large Aperture
S-band structure

LAS 10 MV/macceleration

Solenoids% primary e- 3.2 GeV, 10 nC x 2 bunch, 50 Hz% tungsten target% AMD system (5.0 T x 200mm+ 0.4 T x 15m)
Flux Concentrator DC solenoids% KLY1 2m LAS x 2 (14 MV/m), aperture 2a = 32 -> 30 mm (typical S-band ~20 mm)% KLY2 2m LAS x 4 (10 MV/m), aperture 2a = 32 -> 30 mm Deceleration capture% e+ beam energy at capture section exit : 110 MeV
e+ yield: N(e+)/N(e-) = 49 % at 1.1 GeV DR
Linac Upgrade Status towards SuperKEKB

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20

Flux Concentrator Assembly
FC assembly

primary
e- beampositronproduction
Targetquick detachable power & water connection
to minimize worker's radiation dose
Flux
Concentrator
BridgeCoilse+ beam
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

21



e+/e- beam switching at target
side3view
10 nCprimary e-bridge coils

DC QM spoilertargetrear3viewsolenoid

LAS Accel.
structure

targetdiameter
4.0 mmtargetoffset
3.5 mme+
beamhole

5 nC injection e-
FluxConcentrator

pulse ST
pulse QM

2.0 mmFC offset

holediameter
2.0 mm
7.0 mm
FC aperture

Two possible schemes of beam switching by orbit bump1) e+ on-axis, e- offset-> e- emittance growth by solenoid kick induced orbit2) e- on-axis, e+ offset
we take this scheme.
-> e+ yield degradation (50% -> 10%)
T.Kamitani
Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

RF 電子銃開発!A1 電子銃 (GR_A1) の試験が進行中"擬似進行波型空洞や Ir2Ce 陰極、Yb Fiber laser など、今年度の大きな進展"Energy 幅・安定度制御のための Laser 光時間構造制御を行う必要がある"その前に Beam 開発用の Beam 供給とその安定化が重要"陽電子生成用の一次電子も当面 RF 電子銃で生成するが、熱電子銃も捨てず、得失をよく検討する"新規開発の Component が多いので、経験の積み重ねが重要と思われる

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

23

RF Gun GR_A1 Overall Structure
Regenerative AmplifierOscillator

Linac Upgrade Status towards SuperKEKBMultipass Amplifier

K.F, KEK, Dec.2013.

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Regenerative Amplifier

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K.F, KEK, Dec.2013.

25

Multipass Amplifier

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26

Quadruple Frequency

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27

Linac Upgrade Status towards SuperKEKB

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GR_A1 : 5.1 nC / bunch

Horizontal position /mm

Vertical position /mm

Charge /nC

Charge Trend / Stability

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

Beam Trend / StabilityLinac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

Horizontal / Vertical stability

Linac Upgrade Status towards SuperKEKB

K.F, KEK, Dec.2013.

Dual-layer Controls

Virtual Accelerator-based Controls! Multiple closed loops were installed on each PPM VA
independently" Tested at KEKB
e− Gun"e– BT (PF: 2.5GeV, 0.1nC)"

PF Injection

ARC"

e+ Target"e− Gun"Event-basedControl System

ARC"

KEKB-LER Injection

Primary e– (4GeV, 10nC)

e+ BT (KEKB: 3.5GeV, 0.6nC)"

e+ Target"e− Gun"ARC"

KEKB-HER Injectione+ Target"e– BT (KEKB: 8GeV, 1.2nC)"

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32

Event-based
Control System! Four PPM VAs at least
for SuperKEKB project(maybe withadditional PPM VA
for stealth beam)

Every
20 ms

F.B
e− GunARC

F.B

PF Injectione– (2.5GeV, 0.2nC)

F.B
e− GunARC

Damping ring

SuperKEKB-LER Injection

F.B

e– (3.5GeV, 10nC)

F.B

e+ Targete+ (4GeV, 4nC)

e− GunARC

SuperKEKB-HER Injection

F.B

e– (7GeV, 5nC)
e− GunARC

F.B

PF-AR Injection

F.B
e– (6.5GeV, 5nC)

Linac Upgrade Status towards SuperKEKB

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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 SuperKEKB

K.F, KEK, Dec.2013.

Injector Commissioning Plan and Issues

e- beam
Bunchcompression@ J-ARCBNS damping@ Sector A-B
20 mm⋅mrad, 0.08%
energy spread, 5 nC,
two bunchComponent
Alignment& BBA

e- RF gun(5 nC)

Offset injection@ Sector C-5
HighprecisionmonitorUniform
longitudinal
beamdistributionInjector Commissioning Plan and Issues

e+ beamTiming system/Bucketselection

Damping ring
operation
Large aperture
S-band structure
20 mm⋅mrad, 0.07%
energy spread, 4 nC,
two bunchComponent
Alignment& BBA

e- RF gun(10 nC)

Flux
concentratorまとめ!(2015 年に目標を達成する) 建設計画からは一部遅れている部分があるが、現在のところ概ね期待どおり!震災復旧も順調 (ただし作業負荷は高くなっている)!昨年は小さな障害が多かったが、今年は少し大きめの障害が少数!最終的に達成すべき目標 Beam quality 達成と、2015年から運用する当面の Beam の供給を、Balance よく計画する!資源が厳しいので、2015 年までの開発に固執せず、安全に配慮し、最適な選択肢を選び、ひとつずつ開発項目をこなしていく
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37

Mt. Tsukuba

Thank you
SuperKEKB
dual rings
PF-AR
PF

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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

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matching
sectione+ capture section

K.F, KEK, Dec.2013.

39

まとめ!2 年後の MR 入射コミッショニングに向け、ひとつのMilestone は越えた!震災の影響の懸念をある程度払拭した!SuperKEKB のビーム仕様を満たすための試験の準備が整ってきた!まずは T=0 の 1nC ビームのエミッタンスとエネル
ギー幅を満足し、さらに大電流ビームのビーム特性達成を目指す"そのために、機器の安定度向上、ビーム・マイクロ波・タイミング測定、大電流加速、ビーム安定化機構、特にエミッタ
ンス・エネルギー幅制御の確立、などをひとつずつ段階を踏んで進めて行く

Linac Upgrade Status towards SuperKEKB

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