Injector Linac Experiencesat KEKB / SuperKEKB
Kazuro Furukawa
Injector Linac, KEK<kazuro.furukawa@kek.jp>

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

1

SuperKEKB overview
KEKB Injector Linac
SuperKEKB Injector Linac Progress
Operation

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

2

Linac Upgrade Overview

Mission of electron/positron Injector in SuperKEKBu 40-times higher Luminosityv20-times higher collision rate with nano-beam scheme³  Low-emittance even at first turn³  Shorter storage lifetime

 Low-emittance beam from LinacvTwice larger storage beam Higher beam current from LinacuLinac challengesvLow emittance e³ with high-charge RF-gunvLow emittance e+³ with damping ringvHigher e+ beam current³ with new capture sectionvEmittance preservation³ with precise beam controlv4+1 ring simultaneous injection
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

3

SuperKEKB master schedule�
・・・�

JFY2010�

JFY2011�

JFY2012�

JFY2013�

JFY2014�

JFY2015�

JFY2016�

JFY2017�

・・・�

Now (Apr, 2016)�

KEKB
operation�
Dismantle KEKB�

Phase 2 commissioning：�l Low beta* tuning at IP�
l Collision tuning�l Start physics data taking�SuperKEKB upgradeconstruction�
LargeEarthquake�Mar.2011�

Phase 3：�l Physics run with fullBelle II with VXD�Startup,conditioning,etc.�
Phase 1�SuperKEKB
operation�

Phase 1 commissioning：�
l Basic machine tuning�l Low emittance beam tuning�l Vacuum scrubbing�l Started on Feb.1.2016.�

Akai, Mar.2016.�
Injector Linac Experience at KEKB/SuperKEKB

Phase 2、3�DR�For ~10 years�

DR commissioning
starts prior to Phase 2�

Belle II install,�
QCS install�

K.Furukawa, KEK, FCC2016, Apr.2016.

4

Required injector beam parametersStage

KEKB (final)

Item

e+

e–

e+

e–

e+

e–

Energy3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

Bunch charge

Primary
e-10nC

1 nC→ 1 nC

Present Phase-I SuperKEKB (final)

Primary e8nC
→ 0.4 nC

1 nC

Primary e-10nC→ 4 nC

5 nC

Norm. Emittance(γβε)(µrad)

2100

200

2400

150

100/20(Hor./Ver.)

50/20(Hor./Ver.)

Energy spread

0.125%

0.125%

0.5%

0.5%

0.1%

0.1%

No. of Bunch / Pulse

2

2

2

2

2

2

Repetition rate

50 Hz

Simultaneous top-up
injection

3 rings(KEKB e–/e+, PF)

Injector Linac Experience at KEKB/SuperKEKB

25 / 50 Hz

50 Hz

No top-up

4+1 rings(SuperKEKB e–/e+, DR,
PF, PF-AR)
K.Furukawa, KEK, FCC2016, Apr.2016.

5

SuperKEKB overview
KEKB Injector Linac
SuperKEKB Injector Linac Progress
Operation

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

6

KEKB

u 1995-1999: Construction

KEKBu 1999-2010: Operationu KEKB B-Factoryv Electron-Positron Asymmetric Colliderv Pursue study on CP-violationin B-meson systemv ~3km dual ring:³ Electron (8GeV - 1.4A)³ Positron (3.5GeV - 1.8A)³ Achieved world highest luminosity 2.1 x 1034
³ Shared injection to light sources, PF and PF-AR

Operated with SC Crab Cavities

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

7

KEKB Operation Improvement (base of SuperKEKB)
red: beam current (e-, e+)purple: vacuum (e-, e+)yellow: luminosity
green: integrated luminosity

Belle/KEK

May.2000
Apr.2003
Dual Bunch e+
Feb.2005
Continuous
Injections
Dec.2008
Crab Cavities andSimultaneous Injection
Injector Linac Experience at KEKB/SuperKEKB

Keeps world
luminosity record
K.Furukawa, KEK, FCC2016, Apr.2016.

9

Operation Improvements (1)uMany slow closed feedback loops for beamvBeam orbit, energy, and often devicevUntil related hardware was stabilizedvAlso useful when studying beamsuTolerance study to understand fluctuationsvFor example, single-parameter tolerance to keep 90% ofbeam transmissionvGood reference to consider the beam stabilityuFight against discharges in structuresvEspecially at 1st cavities after gun and positron targetvSolenoids, beam loss, etc.
vOptimization for rf power and shorter rf pulse
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

10

Operation Improvements (2)uDual bunches in a pulse for higher beam
chargev50 Hz x 2 bunches doubled the injection beamvEspecially for positronuFaster beam switching, continuous injectionvBetween electron / positron and for light sourcesvMagnet hysteresis considerationuEven faster simultaneous injectionsvPulse-to-pulse modulation at 50 Hz (20 ms)v~150 parameters were switched in KEKB for 3 beams³~250 parameters in SuperKEKB for 4 beams
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

11

SuperKEKB at 2002
uSome consideration on upgrade forSuperKEKB was presented already in 2002uMuch different from present form, but thisshows a project needs a long lead timevLater,vEnergy exchange
was rejectedvNano-beam scheme
was employed

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

12

SuperKEKB overview
KEKB Injector Linac
SuperKEKB Injector Linac Progress
Operation

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

13

Linac Upgrade Overview

Mission of electron/positron Injector in SuperKEKBu 40-times higher Luminosityv20-times higher collision rate with nano-beam scheme³  Low-emittance even at first turn³  Shorter storage lifetime

 Low-emittance beam from LinacvTwice larger storage beam Higher beam current from LinacuLinac challengesvLow emittance e³ with high-charge RF-gunvLow emittance e+³ with damping ringvHigher e+ beam current³ with new capture sectionvEmittance preservation³ with precise beam controlv4+1 ring simultaneous injection
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

14

Schedule

RF-Gun e- beamcommissioning
at A,B-sector

Linac Schedule Overview

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

Phase1: high emittance beam for vacuum scrub
Phase2,3: low emittance beam for collision

Time →
Location↓
Beam
Licensesin steps

Low
Emittance
Beams

4+1 Ring
Injections

DR
Commiss.
1 nC
Phase1

Without Top-up: Electron: Positron: Low current electron

Injector Linac Experience at KEKB/SuperKEKB

non damped e+ commiss.
at 1,2, 3,4,5 sectors
e- commiss. at A→5 sectors

2 nC
Phase24 nC
Phase3

Direct PF-AR BT
damped e+ commiss. Improved
at 1→5 Qe+ = 1~4nC RF gun
e- commiss.
at A→5 Qe- = 1~5nC

K.Furukawa, KEK, FCC2016, Apr.2016.

15

Required injector beam parametersStage

KEKB (final)

Beam

e+

e–

e+

e–

e+

e–

Energy3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeVStored current

1.6 A

1.1 A

1A

1A

3.6 A

2.6 A

Life time

150 min.

200 min.

100 min.

100 min.

6 min.

6 min.

Primary e-10nC

Present Phase-I

Primary e- 8nC

Bunch charge→ 1 nC

1 nC→ 0.4 nC

Norm. Emittance(γβε) (µrad)

2100

200

2400

Energy spread

0.125%

0.125%

No. of Bunch / Pulse

22

Repetition rate

50 Hz

Simultaneous top-up
injection (PPM)

3 rings(KEKB e–/e+, PF)

Injector Linac Experience at KEKB/SuperKEKB

1 nC

SuperKEKB (final)

Primary e-10nC→ 4 nC

5 nC

150

100/20(Hor./Ver.)

50/20(Hor./Ver.)

0.5%

0.5%

0.1%

0.1%

2

2

2

2

25 / 50 Hz

50 Hz

No top-up

4+1 rings(SuperKEKB e–/e+, DR,
PF, PF-AR)
K.Furukawa, KEK, FCC2016, Apr.2016.

16

Subjects to Consider
Phronesis

DR ECS/BCS

SafetyTimingmonitorPhase-IIScheduleu Phronesis needed(Greek: Practical wisdom,
Ability to understand the
Universal Truth)

BBA

RTL abort

Balance

LLRF monitor

Low emittanceJun.2017
Nov.	

DRu Have to consider
too many subjects !

BPM

Alignment

Temporalmanipulation

1 nC e+Phase-I
Feb.2016

GR̲A1 5nC

Bunch
compression

GR̲A1 8 nC

Resources

GR̲A1 10nC
Laser
development

Energy spread

FC / LAS

PF-AR 6.5GeV

Injector Linac Experience at KEKB/SuperKEKB

Pulsed bend

Beamstability

DC FODO

4 nC e+Phase-III
Oct.2018

Availability

Conditioning

PF Top-up

4-ringinjection

Strategic

maintenanceGR̲A1 1nC e-

2nC e+

3-ringinjection

Orbit control

Compatible
OpticsGR̲A1 for PF

Pulsed PS
development

Pulsed quad
Equipment
stability

GU̲3T dual feed
modulator

KL/AC̲44
replacement

BudgetPF-AR 3GeV

K.Furukawa, KEK, FCC2016, Apr.2016.

17

Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB (1)u High-charge low-emittance RF gun developmentv QTWSC cavity and Ir5Ce photo cathodedevelopmentsv Laser development is underway

Quasi traveling wave
side couple cavity

Ir5Ce
Cathodeu Positron generator commissioning
Positron generatorv Good agreement with the simulation resultsv Will solve discharge issuesu Precise alignment for emittance preservationv Recovering after large earthquake in 2011v Reaching specification of 0.1~0.3mmv Longer term stability will be solvedu Utility upgrade during FY2014v for electricity (+1.5MW) and cooling water (+1400L/min)
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

18

Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB (2)u High-power microwave modulator upgradesu Low-level RF controls/monitor upgradesv Pulse-to-pulse modulation (PPM) between 4+1 ringsv More spaces for increased number of devicesu Beam instrumentationv Large/small aperture beam position monitors (BPM)v Precise/fast and synchronized BPM readout systemv Wire scanners and beam loss monitorsv Streak camerasv (Deflectors, etc.)u Event-based control and timing system upgradesv Combination of MRF & SINAP modulesv Essential for PPM operationv Precise timing & synchronized controlsv Bucket selection at DR and MRSINAP event modules

Injector Linac Experience at KEKB/SuperKEKB

Beam wire scanner

K.Furukawa, KEK, FCC2016, Apr.2016.

19

Positron Enhancement

20	

Positron generation for SuperKEKB
side	
  view	
10 nC
primary e-	bridge coils	

DC QM	
 spoiler	target	solenoid	
LAS Accel.
structure	

primary
e- beame+	
 positron
production

beam
hole	

5 nC injection e-	Target
Flux
Concentrator	

pulsed ST	pulsed QM	

FluxConcentrator
BridgeCoils
e+ beam

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 (2mm) for passing electrons beside target (3.5mm)
Recently, facing discharge difficulties at maximum field
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

20

RF gun for low-emittance electron

RF-Gun development strategy for SuperKEKB
u Cavity : Strong electric field focusing structurevDisk And Washer (DAW)=> 3-2, A-1(test)vQuasi Traveling Wave Side Couple (QTWSC) => A-1=> Reduce beam divergence and projected emittance dilutionu Cathode : Long term stable cathodevMiddle QE (QE=10-4〜10-3 @266nm)
vSolid material (no thin film) => Metal composite cathode=> Started with LaB6 (short life time)=> Ir5Ce has very long life time and QE>10-4 @266nm

u Laser : Stable laser with temporal manipulationvFiber laser oscillator / amplifier = Yb dopedvLD pumped laser medium => Nd / Yb dopedvTemporal manipulation => Yb doped=> Minimum energy spread
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

21

RF gun for low-emittance electron

Energy spread reduction using temporal manipulation
M. Yoshida

Energy spread of 0.1% is required for SuperKEKB
synchrotron injection.
15nC

3

t
2.5

5nC10nC

20nC

Gaussian
σE/E (%)

2

1.5

1

t

Square 5nC
10nC

0.5

15nC
20nC

0
0

5

Injector Linac Experience at KEKB/SuperKEKB

10 5nC electron
15
FWHM (ps)20
10 - 15nC 25

30

possible primary beam for positron
K.Furukawa, KEK, FCC2016, Apr.2016.

22

RF Gun Result Example

5.6 nC bunch charge
was observed.

RF gunA1 sector at KEK linac

beam size measurement for Q-scanx32.7 3.1 mm-mrad
Injector Linac Experience at KEKB/SuperKEKB

Q-scan emittance measurementy10.7 1.4 mm-mrad
K.Furukawa, KEK, FCC2016, Apr.2016.

23

Alignment

Emittance Preservationu Offset injection may solve the issueu Orbit have to be maintained preciselyu Mis-alignment should be <0.1mm locally, <0.3mm globally
Mis-alignment leads to Emittance blow-up

Orbit manipulation compensates it

100 samples
Sugimoto et al.
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

24

Pulse-to-pulse modulationu Four PPM virtual accelerators
for SuperKEKB project

Event-based
Control System

Every
20 ms

F.B

Based onDual-tier controls withEPICS and event-systeme− GunARC

Independent parameter setsfor each VA (20ms)>200 parameters
for equipment controls
many more
for beam controls
maybe with additional PPM VAof stealth beam
for measurement

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)

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

25

SuperKEKB overview
KEKB Injector Linac
SuperKEKB Injector Linac Progress
Operation

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

26

20000	

8 	

18000	

7 	

16000	

Operation Time / year [hrs]	

14000	

Total Operation Time [hrs]	

Machine Failure [%]	Total Operation Time / 10 [hrs]	

Operation Time / year [hrs]	

Injector Linac Operation History6 	

Machine Failure [%]	12000	

5 	

10000	

4 	

8000	

3 	

6000	

2 	

4000	

2000	

TRISTAN	

KEKB	

1982	

1983	

1984	

1985	

1986	

1987	

1988	

1989	

1990	

1991	

1992	

1993	

1994	

1995	

1996	

1997	

1998	

1999	

2000	

2001	

2002	

2003	

2004	

2005	

2006	

2007	

2008	

2009	

2010	

2011	

2012	

2013	

2014	

0	

PF	

1 	

0 	

FY	

 Earthquake

Routine maintenance was important to improve the reliability(Failure rate includes rf trips)
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

27

Injector Linac Energy Management
1.1 GeV
Damping Ringcirc. 136 m	

Low emittanceRF gun	

1.5 GeV

e-/e+ beam with different
bunch charge and energy
are accelerated by 50 Hz
repetition rate.

BCS	

3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)	ECS	3T
RF gun	e+ target &LAS capture section	chicane

PF
PF-AR
ECS	

HER LER

5 nC x2

4.219 GeVe-

HER: 7GeV ePF-AR: 6.5GeV e5nCx1

LER: 4GeV e+
4 nCx2e+ target
1.5 GeVe+

1.1 GeV

e-/e+ compatible optics

Injector Linac Experience at KEKB/SuperKEKB

PF: 2.5 GeV e0.1nCx1

Optics is changed for each pulse by using
pulsed quads (Doublet) & steering magnets
K.Furukawa, KEK, FCC2016, Apr.2016.

28

Beam Manipulation Study
At 180-deg
arc

Optics design with R56 = 0 and -0.6 for bunch compression

BPM will be
replaced with
5-timesbetterresolution
Streakcamerashould follow

Measurement of dispersion functions for R56 = 0 and -0.6
Soon with timing measurement by streak camera

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

29

Linac Optics Measurement / Managementu Wire scanner is used to manage twiss parameters along linacu ~6 sets of wire scanners will be installedu Wire scanner measurements performed everydayu If necessary (if Bmag is large), re-matching is performed by operatoru For pulse-to-pulse vertical measurement, X-band deflector will be installed
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

30

Typical Phase-1 Daily Operation
More than
300mA stored
this week in theboth e-/e+ rings
In daytime
increases beam
current, andperforms optics
studies
In night time
continue vacuum
scrubbingNo collision yet
Collision
expected at theend of 2017

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

31

Examples of Operational PanelsuaInjector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

32

Schedule

Radiation control licensesu Step-by-step upgrade of beam limitsu Final goal in linac is 1250/625 nA before/after targetu License applicationsvFall.2013. 10 nA at #28 dump, 1250 nA at #A2 dumpvSpring 2014. New utility rooms, 50 nA at #61 straight dumpvJun.2015. 200 nA at #15 targetvEarly 2016. 800 nA at #15 target, 625 nA at #61
vSometime 2017.(?) 1250 nA at #15 targetu Shield, shield, shield, shield …
v Gun, 180deg-arc, Target, Electron stopper, Collimator, etc.

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

33

Recent works

Recent Works
Positron generator
at #15 region

Iron shield

Positron generator complex

Guns
at #A1 region

Thermionic gun
for high-current beam

RF gunfor low-emittance beam

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

34

Summary

Summaryu We learned a lot during KEKB construction and operationu It contributed to achieve the world highent luminosityu Injection into SuperKEKB is another challenge with higher beam
charge and lower emittanceu Steady progress towards designed injection beam in stepsv Alignment: almost confident on the required precision (0.1-mm local, 0.3-mm
global), need to maintain for longer termv Positron generator: another license test, need discharge analysisv Thermionic gun: re-commissioned, workingv RF gun: following recommendations at review meetingsv Need much more radiation shieldu Will balance between final beam quality and progressive operationu Will select optimized route depending on available resourcesu With some Phronesis we may enjoy beam commissioning
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

35

Mt. Tsukuba

Thank you
SuperKEKB
dual rings
PF-AR
PF

600m Injector
Linac

Conference papers at <http://www-linac.kek.jp/linac/>
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

36

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

37

Alignment

Floor vertical movement
in a half year from summer to winter

C3

11

Injector Linac Experience at KEKB/SuperKEKB

18

28

38

Higo et al.

48

K.Furukawa, KEK, FCC2016, Apr.2016.

38

Thermionic Gun

Preparation of Thermionic Gunu Refurbished and recommissionedv Raise by 75cm not to conflict with straight RF-gun³ As well as angled RF-gunv ~ Jun.2015.

u Beside RF gun, thermionic gun may servev electrons in phase-Iv primary electron for positron generation in phase-II and later
Thermionic gun

RF gunInjector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

39

SADscriptsuMany machine diagnostic and correction/
feedback tools

Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

42

KEKB and Linac Operation

SADScriptu Mathematica-like Languagev Not Real Symbolic Manipulation (Fast)v EPICS CA (Synchronous and Asynchronous)
CaRead/CaWrite[ ], CaMonitor[ ], etc.

v (SQL Database)v Tk Widgetv Canvas Draw and Plot (Mathematica-like Plot)³ High quality plots to be used in publicationsv KBFrame on top of Tkv Data Processing (Fit, Modeling, FFT, Optimization, …)v Inter-Process Communication (Exec, Pipe, etc)
System[ ], OpenRead/Write[ ], BidirectionalPipe[ ], etc.

v Greek Letterv Full Accelerator Modeling Capability (this the main part, of course)v Also Used for non-Accelerator Applicationsv Other institutes depend on MAD, XAL, but very different architecture
Injector Linac Experience at KEKB/SuperKEKB

K.Furukawa, KEK, FCC2016, Apr.2016.

43