Injector and Collider Rings ofSuperKEKB B factory– with some emphasis on the injector –Kazuro Furukawa
for SuperKEKB Injector and Rings, KEK<kazuro.furukawa@kek.jp>

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

1

Mt. Tsukuba

3km SuperKEKB
Collider dual rings
PF-AR
PF
Damping Ring

Injector Linac and SuperKEKB at KEK

600m Injector
Linac

K.Furukawa, KEK, WAO2018, Oct.2018.

2

KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

3

KEKB Configuration (1999 – 2010)
uElectron Positron Accelerator Complex at KEK
2.5 GeV/cPF

LER
3.5 GeV/ce+ BT

e+, e- Linac
e- BT
Linac delivered:for PF: 2.5 GeV e–
for PF-AR: 3 GeV e–
for KEKB: 8 GeV e–
3.5 GeV e+

6.5 GeV/c
PF-AR
HER
8 GeV/c

KEKB

Belle

Shared single injector between 4 storage rings
Shared beam transport line between HER & PF-AR
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

4

KEKB DesignuMaximum reuse of TRISTAN inheritanceuHowever, still many improvements applied, ex.
vMany bunch collisions with dual ring collider³Energy asymmetry for the boost of center of mass of Bs

vFull energy injection³Energy upgrade with SLED RF pulse compressor
w from 2.5 GeV (400 m) → 8 GeV (600 m)

vInjection aperture of 30 ps³Slight RF frequency modification to have an integer relation
w Linac 2856 MHz
w Ring (508.5 MHz →) 508.9 MHz: 10.386 MHz x 275: 10.386 MHz x 49

vAnd so on
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

5

SuperKEKB Configuration (2018 – )uNewer Electron Positron Accelerator Complex
Damping
at KEK2x beamRing
Low emittance
RF-gunPF
2.5 GeVe–

Injector Linac

e+

600 m

High efficiency
e+ generator

current

e–

e+ BT

PF-AR
6.5 GeVe – BT

Beam from Injector and Storage Current
SuperKEKB: 7 GeV e2600 mA
4 GeV e+3600 mAPF:
2.5 GeV e450 mA
PF-AR:
6.5 GeV e60 mA

HER
7 GeV

SuperKEKB
3 km

LER
4 GeV

Belle II
40x
Luminosity

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

6

SuperKEKB DesignuMaximum reuse of KEKB inheritanceuHowever, still many improvements applied, ex.
vNanobeam collision scheme (with beam sizes of 50nm)³For 40-fold higher luminosity avoiding hourglass effectvPrecise superconducting focusing magnets³With many corrector coilsvRF system additions for twice higher beam current
vMany magnet additions/replacements for low emittancevDamping ring construction
vPF-AR direct beam transport line construction
vMany improvements to inject even under nanobeam³At injector linac
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

7

Operator Shifts
u Operators for every 8-hour
vKEKB control room for SuperKEKB, PF-AR, Linac (Beam)³ 3/2/2 Operators for SuperKEKB, PF-AR [A]³ 1/1/1 Operators for Linac [B]³ 1.5/1.5/1 Commissioning shifts for SuperKEKB and Linac [C]³ 0.5/0.5/1 Safety shifts for SuperKEKB [D]vLinac control room
³ 1/1/1 Operators for Linac (Hardware) [B]³ 1/1/1 Safety shifts for Linac [E]vCryogenic control roomvPF control roomu Membersv Outsourcing: [A] x12, [B] x12v SuperKEKB Staff: x55, Linac Staff: x30 (basically all staff)
v Staff: [C] x50, [D] x48, [E] x27 (overlapping)
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

8Injector Operation Statistics
uStatistics
High demands

Operation hours (hour)
Failure rate (%)

7,000

Beam loss rate (%)

6,000

7

6
SuperKEKBLight sources

KEKB and light sources
5,000

Hours

8

5

4,000

4

3,000

3

Operational balance

2,000

Rates (%)

8,000

Injector operation hours and failure rates

Light sources
2

Demands again

1,000

1

0

0
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Fiscal year

u Failure: device failures that prevent optimum performanceu Beam loss: time when beam injection was really impossible
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

9KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

10

PEP-II/SLAC and KEKBuWe exchanged ideas between PEP-II and KEKB
vViewed each other from control rooms³Friendly competition
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

11

KEKB

Daily Morning MeetingvEvery morning on weekdays and weekend from 9 a.m.

uVery often novel ideas are proposed for
performance improvement of beams, devices andoperation
vBright new idea in the morning meeting could make theoperation much advanced in the evening³Only some ideas are effective, so rapid prototyping is importantvEPICS control framework and Scripting languages³Especially, SADscript as a bridge btw. Accelerator simulation,
Numeric manipulation, Graphic interface and EPICS controls

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

12

Operational Optimizations
uFor example, run-length optimizationu Hundreds oftools weredeveloped
u with graphicaluser interface
for operatorsu oftenautomatedu Past examples
follow from thenext slide
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

13

KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

14

Two bunches in a pulsevAs the stored beam current in MR increases, much
more injection beam current was required
vEspecially for the positron injection rateuTwo bunches in a pulse acceleration in orderto to double the positron beam current planned
vMinimum bunch separation of 96 ns (10.386 MHz)vParallel dual grid pulsers for a single cathodevBeam instrumentation with 96 ns separationvTiming manipulation and bucket selection
vEnergy equalization

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

15

Dual-bunch Energy Equalization, and Feedback
u Energy equalization is important for stable operation
Measurement at bunching section
after energy equalization
with RF pulse timing

Beam loading compensation

Stabilization at bending section
with SLED timing

First Bunch

SLEDSecond Bunch

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

16

KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

17

Continuous Injection
vDetector data acquisition stopped during the injection
and the detector high voltage (HV) preparationvEspecially for the positron injection rateuContinuous Injection with detector HV applied
was another major step forward
vFor higher integrated luminosity
vby detector improvements, esp. CDC, TOF, DAQ
vwith certain benefit from collision with crossing angle³without bending magnet at IP, for lower backgroundvThen, approximately 26% gain achieved

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

18

Continuous injectionua
2004, after continuous injection was applied
Data acquisition continued during injection(8-hour history of beam current, luminosity, etc.)

2003, before continuous injection was applied
Data acquisition stopped during injection(8-hour history of beam current, luminosity, etc.)

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

19

Beam mode switching improvementsu Continuous injection was applied in 2004
Beam mode switching
80000
70000
60000

Count

50000
40000
30000
20000
10000
0
1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

Year

u Switched 360 times / day in 2008
u Simultaneous top-up injection was applied in 2009
v to enable switching every 20 ms (4 million times / day)Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

20

KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

21

Simultaneous Top-up InjectionsvEven faster beam mode switches

uPulse-to-pulse modulation (PPM) at 50 Hz³PPM was applied at PS/CERN (1977?) at 1.2 s

v~150 parameters were switched every 20 ms for 3
beams

uMany Hardware improvements as well as
controls
vPF top-up injection for higher quality experiments
vSensitive luminosity tuning with Crab cavities³Many more parameters in SuperKEKB for 4 beams
Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

22

Dual-layer Controls

Fast Global Synchronous ControlsuEvent-based controls (MRF)
u114.24MHz event rate, 50Hz fiducials
uTiming precision < 10ps

Dual layer control concept
Dual Layer Controls

Event Generator

CentralOPI

EPICS
Channel Access

IOC

IOC

IOC

IOC

EVG

EVR

EVR

EVR

MRF
Event Link

SH_A1
KL_B5/B6

SB_B

Injection

SB_Ae­ GunARC

e– BT (PF: 2.5GeV, 0.1nC)

Cont-ABC
KL_51/52
SB_C

SB_1

SB_2

SB_3

SB_4

SB_5

e+ BT (KEKB: 3.5GeV, 2nC)

e+ Target
Cont-1

Cont-2

Cont-3Cont-4Cont-5

Event Receivers
Injector Linac and SuperKEKB at KEK

e– BT (KEKB: 8GeV, 2nC,
PFAR: 3.0GeV, 0.1nC)

K.Furukawa, KEK, WAO2018, Oct.2018.

23

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 and SuperKEKB at KEK

Keeps world
luminosity record
K.Furukawa, KEK, WAO2018, Oct.2018.

24

KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

25

Injector Linac Mission

Mission of Electron/positron Injector in SuperKEKB
v For 40-times higher luminosity in SuperKEKB collider
v Low emittance & low energy spread injection beams with 4 times higher beam current³ New high-current photo-cathode RF gun³ New positron capture section³ Positron damping ring injection/extraction³ Optimized beam optics and correction³ Precise beam orbit control with long-baseline alignment³ Simultaneous top-up injection to DR/HER/LER/PF/PFARv Balanced injection for the both photon science andelementary particle physics experiments
Low emittance
RF-gunDamping
Ringe–

Injector Linac

e+

600 m

High efficiency
e+ generator

2x beamcurrent

PF
2.5 GeV

e–

e+ BT

PF-AR
6.5 GeVe – BT

Beam from Injector and Storage Current
SuperKEKB:
7 GeV e2600 mA
4 GeV e+3600 mAPF:
2.5 GeV e450 mA
PF-AR:
6.5 GeV e60 mA

HER
7 GeV

SuperKEKB
3 km

LER
4 GeV

Belle II
40x
Luminosity

Injector Linac and SuperKEKB at KEK

The single injector would behave as
multiple injectors to multiple storagerings by the concept of virtual
accelerator
K.Furukawa, KEK, WAO2018, Oct.2018.

26

SuperKEKB Schedule
SuperKEKB/Belle II schedule
Calendar year

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

Japan FY

JFY2010

JFY2011

JFY2012

JFY2013

JFY2014

JFY2015

JFY2016

JFY2017

JFY2018

JFY2019KEKB operation

・・・
・・・

SuperKEKB LER & HER upgrade construction
Start-up

Phase 1w/o QCS
w/o Belle II

Belle II upgrade construction

IR renovation(install QCS, etc.)

Phase 2

Belle II roll-in

w/ QCS
w/ Belle II (no VXD)VXD installation

Positron damping ring (DR) construction

w/ full Belle II

Phase 3
DR commissioning

Injector Linac upgrade construction & operation

Injector Linac and SuperKEKB at KEK

operation
for years

K.Furukawa, KEK, WAO2018, Oct.2018.

27

Linac Beam Property Requirements

Required injector beam parametersStage

KEKB (final)

Phase-I

Phase-II

SuperKEKB(final)

Beam

e+

e–

e+

e–

e+

e–

e+

e–

Energy3.5 GeV

8.0
GeV

4.0 GeV

7.0
GeV

4.0 GeV

7.0
GeV

4.0 GeV

7.0 GeVStored current

1.6 A

1.1 A

1A

1A

1.8 A

1.3 A

3.6 A

2.6 A

Life time (min.)

150

200

100

100

–

–

6

6

Bunch charge(nC)

primary e- 10

1

0.5

1

primary e- 8

→1

1

→ 0.4

Norm. Emittance(γβε) (µrad)

1400

310

1000

130

200/40(Hor./Ver.)

Energy spread

0.125%

0.125%

0.5%

0.5%

Bunch / Pulse

2

2

2

2

Repetition rate

50 Hz

Simultaneous
3 rings
top-up injection(LER, HER, PF)(PPM)
Injector
Linac and SuperKEKB at KEK

primary e- 10
→4

4

150

100/15(Hor./Ver.)

40/20(Hor./
Ver.)

0.16%

0.1%

0.16%

0.07%

2

2

2

2

25 Hz

25 Hz

50 Hz

No top-up

Eventually

4+1 rings (LER, HER,
DR, PF, PF-AR)

K.Furukawa, KEK, WAO2018, Oct.2018.

28

Subjects to Consider at Injector
Phronesisu (As of 2014)

SafetyDR ECS/BCS

TimingmonitorPhase-IISchedule

u Phronesis needed(Greek: Practical wisdom,
Ability to understand the
Universal Truth)

BBA

RTL abort

Phase-I
Feb.2016

GR̲A1 5nC

Bunch
compression

Strategic
maintenance

1 nC e+manipulation
3-ringinjection

Orbit control

GR̲A1 1nC e-

2nC e+
Temporal

Balance

LLRF monitor

Low emittanceJun.2017
Nov.

DR

u Have to consider
too many subjects !

BPM

Alignment

GR̲A1 8 nC

GR̲A1 10nC

Availability

Conditioning

Laserdevelopment

Energy spread
Resources

FC / LAS

Beamstability

DC FODO

4 nC e+PF Top-up

Compatible
Optics4-ringinjection

PF-AR 6.5GeV

Injector Linac and SuperKEKB at KEK

GR̲A1 for PF

Phase-III

Oct.2018

Pulsed bend

Pulsed PS
development

Pulsed quad
Equipment
stability

GU̲3T dual feed
modulator

KL/AC̲44
replacement

BudgetPF-AR 3GeV

K.Furukawa, KEK, WAO2018, Oct.2018.

29

Positron Enhancement

30

Positron generation for SuperKEKB

Y.Enomoto et al.

side view
10 nC
primary e-bridge coils

DC QM spoilersolenoid
LAS Accel.
structuretargetprimary
e- beam

e+

beam
hole

positronproduction
5 nC injection e-Target
Flux
Concentrator

pulsed ST
pulsed QM

Flux
Concentrator
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 and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

30

One of Key Component: Photo Cathode RF Gun

Development of Photo-cathode RF Gun
M.Yoshida et al.

u Succeeded in injection during SuperKEKB Phase 1 and 2 commissioningu Employs Yb-doped-fiber and Nd/Yb:YAG
laser, Ir5Ce cathode, QTWSC or cut disk
cavitiesu Stability improving
u Beam instrumentation
improvements andcomparison withsimulation codes underway Bunch width
Beam orbit measurementu Secondary RF gun was constructed
as a backup
u Incorporate suggestions by review committee
for availability and so on

Thermionic gun
Primary RF gun

Quasi traveling wave
side couple cavity

Secondary RF gun
Cut disk cavity

Injector Linac and SuperKEKB at KEK

Ir5Ce
CathodeElectron Guns

K.Furukawa, KEK, WAO2018, Oct.2018.

31

Pulsed Magnet Development

Development and installation of pulsed magnets
v 100 Pulsed magnets and power supplies are installed in 2017 - 2019v 30 quads, 36 steerings, 2 bends, 13 girders were fabricated and installed in 2017v Quads with advanced design in-house for 1 mH, 330 A, 340 V, 1 ms
v Small form factor of 19 inch width and 3U height each, with energy recovery up to 75%
v Steering power supplies were also developed in-housev Essential for SuperKEKB low emittance injection and for simultaneous injection
v 4+1 ring simultaneous injections with virtual accelerator concept³ Long term tests at a stand³ Satisfies specification, 0.01%³ Control synchronization
Injector Linac and SuperKEKB at KEK³ Beam test with two quads³ Successful fast beam switches³ Switching features are confirmed³ Now all in operation

Enomoto, Natsui et al³ Girders are tested as well
³ In-house drawings to save rsc.
³ 1µm alignment precision³ Ready for Phase-3 upgrade

K.Furukawa, KEK, WAO2018, Oct.2018.

32

Pulse-to-pulse modulationu Simultaneous injectionu Four PPM virtual accelerators
for SuperKEKB project F.B

Event-based
Control System

Every
20 ms

e− GunBased onDual-tier controls withEPICS and event-system

ARC

F.B

PF Injectione– (2.5GeV, 0.2nC)

F.B
e− GunIndependent parameter setsfor each VA (20ms)>250 parameters
for equipment controls
many more
for beam controls
maybe with additional PPM VAof stealth beam
for measurement
and optimization
Injector Linac and SuperKEKB at KEK

ARC

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)
K.Furukawa, KEK, WAO2018, Oct.2018.

33

KEKB and SuperKEKB overview
Daily performance improvements
Dual bunches in a pulse
Continuous injection
Simultaneous top-up injection
Upgrade towards SuperKEKB
Summary

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

34

Summary

Summaryu We learned a lot during KEKB operationu It contributed to achieve the world highest luminosity
u SuperKEKB is another challenge with higher beam charge andlower transverse/longitudinal emittanceu Steady progress is made towards designed beam in steps
u We may need to improve the injection further
v ex. stealth beam measurement / optimization, etc

u With some Phronesis we may enjoy beam commissioning

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

35

Mt. Tsukuba

Thank you
3km SuperKEKB
Collider dual rings
PF-AR
PF
Damping Ring

600m Injector
Linac

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

K.Furukawa, KEK, WAO2018, Oct.2018.

36

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

37

Dual-layer Controls

One Machine, Multiple Virtual Accelerators (VAs)u Control/Monitor are carried dependent on a VA
v Mostly independent between VAs

u Independent parameter set for each VA, one of the VAs is controlled at atimev VAs for Injections (HER (e-), LER (e+), PF, PF-AR) and Linac-only in SuperKEKB projecte− Gune– BT (PF: 2.5GeV, 0.1nC)

PF Injection

ARC

e+ Target

Event-based
Control Systeme− GunARC

KEKB-LER Injection

Primary e– (4GeV, 10nC)

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

e+ Targete− GunARC

KEKB-HER Injection
e+ Targete– BT (KEKB: 8GeV, 1.2nC)

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

38

Dual-layer Controls

Multiple Closed Loop Controls Overlappedu Closed loops were installed on each VA independently

e− Gune– BT (PF: 2.5GeV, 0.1nC)

PF Injection

ARC

e+ Targete− GunEvent-based
Control System

ARC

KEKB-LER Injection

Primary e– (4GeV, 10nC)

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

e+ Targete− GunARC

KEKB-HER Injection
e+ Targete– BT (KEKB: 8GeV, 1.2nC)

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

39

SuperKEKB at 2002
uSome consideration on upgrade forSuperKEKB was presented already in 2002
uMuch different from present form, but thisshows a project needs a long lead timevLater,vEnergy exchange
was rejected
vNano-beam scheme
was employed

Injector Linac and SuperKEKB at KEK

K.Furukawa, KEK, WAO2018, Oct.2018.

40

Schedule

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

Linac Schedule Overview 2018

e- commiss.
at A,B,R,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

Low
Emittance
Injections

4+1 Ring
Injections

DR
Commiss.
1 nC
Phase1

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

Injector Linac and SuperKEKB at KEK

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

1 - 2 nC
Phase2

1 - 4 nC
Phase3

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

K.Furukawa, KEK, WAO2018, Oct.2018.

41