Upgrade of KEK Electron/Positron
Linac for the Both SuperKEKB andLight Sources
Kazuro Furukawa
Injector Linac, KEK<kazuro.furukawa@kek.jp>

Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

1

Linac Upgrade Overview

Mission of electron/positron Injector in SuperKEKB
u 40-times higher Luminosity
v20-times higher collision rate with nano-beam scheme³ à Low-emittance even at first turn³ à Shorter storage lifetime

à Low-emittance beam from Linac

vTwice larger storage beamà Higher beam current from Linac

uLinac challenges
vLow emittance e³ with high-charge RF-gun

vLow emittance e+³ with damping ringvHigher e+ beam current³ with new capture section

vEmittance preservation³ with precise beam control

v4+1 ring simultaneous injection
Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

2

Required injector beam parametersStage

KEKB (2010)

Iteme+e–e+e–e+e–Energy

3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

Bunch charge

Primarye-10nC

1 nC→ 1 nC

Phase-I (2016)

Primary e8nC
→ 0.4 nC

SuperKEKB (final)

Primary e-10nC

1 nC→ 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

222222

Repetition rate

50 Hz

Simultaneous top-up
injection

3 rings(KEKB e–/e+, PF)

Injector Linac Status

25 / 50 Hz

50 Hz

No top-up

4+1 rings(SuperKEKB e–/e+, DR,PF, PF-AR)
K.Furukawa, KEK, b2gm, Oct.2016.

3Linac Injector Status
u Phase-3 (Collision exp.) should not be delayedu Injector construction was delayed about 2 years becauseof resource availability
u Important equipment was postponed until FY2017
v Most of damping-ring related epuipment
vMany of lower-emittance related equipment³ including 30 pulsed focusing magnets, 36 steering magnets, ~13 girders

u Minimum of 5 months required to purchase, fabricate,install and testu Supplemental budget in FY2016 is not enoughv Best effort ! (asuming enough budget in FY2017)v KEKB construction³ Linac shutdown for 9 months in 1997, after many devices were fabricated in1996
Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

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Injector Linac Status)$1'*-$%.-1203%2*.- ,.-2)1,*-K.Furukawa, KEK, b2gm, Oct.2016.

5

Pulsed magnet installation
u30 quads and 36 steerings and ~13 girders will
be installed at summer 2017
v1 mH, 330 A, 340 V, 1 ms
vEnergy recovery to save power (~75%)
vCan change the magnetic field every pulse (50 Hz)³To support PPM operation or virtual acceleratorsuMagnets are readyuPower supply tests were OK
uPulsed power supplies and girders will bemass-produced in 2017
Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

6

Pulsed magnet development
uPulsed magnet test standvLong-term stability was confirmed

uSuccessful beam tests
v25-Hz (50-Hz) switchinguGirders were designed
vWaiting for mass-production
vReady for Phase-3 specification
Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

7

Photo cathode RF gun
uSuccessful HER injection during Phase 1
vFor 11 days
vSynch. issues resolved
vEmittance to be improved
Emittance measurement
Bunch profile measurement

Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

8

Photo cathode RF gun
u Secondary RF gun installationv Incorporate recommendations fromreview meetingsv Laser, light guides, cavity, etc
v Installed at the beginning of 2017

Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

9

DR layout

Damping Ring System Layout

M. Kikuchi±1.5%

Energycompression±5%
Collimators in the arc
20% is cut at tailInjector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

10DR timing

Bucket selection in Phase-2 with DRu Without DR, simply wait up to 5120 x 96 ns ~ 490 μsv 96 ns : highest common frequency between linac – ringe− GunKEKB

ARCe+ BT (3.5GeV, 0.6nC)

Primary e– (3.5GeV, 10nC)
e+ Targetu With DR, in order to select arbitrary bucket in MR, have to wait up
to ~4.5 ms, even if a bucket in DR was carefully selectedv Power supply can wait only 2 ms, one of only 2798 buckets in 5120 buckets can beselected, may have to change LLRF condition at latter half of linac every pulse
96ns +e DR (1.1 GeV, 4nC)
>100nse− GunARC
Primary e– (3.5GeV, 10nC)>100ns
96ns

SuperKEKB
e+ BT (KEKB: 4GeV, 4nC)

e+ Targetv Can be a big challenge in LLRF precision
Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

11

Subjects to Consider
Phronesis

SafetyDR ECS/BCS

Timingmonitor

Phase-IISchedule

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

BBA

RTL abort

Balance

LLRF monitorLow emittanceJun.2017
Nov.
Jan.2018

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 Status

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
stabilityGU̲3T dual feed
modulator

KL/AC̲44
replacement

BudgetPF-AR 3GeV

K.Furukawa, KEK, b2gm, Oct.2016.

12Injection for Both Experimentsof Light-source and B-factory
uProper operation schedule to meetexperimental characteristics of those storage
rings
uSearch for common ground with respect for
those experimentsuShould find and confirm solutions in gradualchangesuImprove the machine using virtual accelerator
concept, if applicable
Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

13

Pulse-to-pulse modulation

Event-basedControl Systemu Four PPM virtual accelerators Every
20 ms
for SuperKEKB project
F.B
e− GunBased onDual-tier controls withEPICS and event-system

ARC

F.B

PF Injectione– (2.5GeV, 0.2nC)

F.B
e− GunDamping ring

Independent parameter sets ARC SuperKEKB-LER Injection
for each VA (20ms)
e (3.5GeV, 10nC)>200 parameterse TargetF.B
for equipment controls
e Gunmany more
ARC
SuperKEKB-HER Injection
for beam instrumentation

F.B–+e+ (4GeV, 4nC)

−maybe with additional PPM VAof stealth beam
for measurement

F.B

e– (7GeV, 5nC)
e− Gun

ARCF.B

PF-AR Injection

F.B
e– (6.5GeV, 5nC)

Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

14

SummarySummaryu Injection into SuperKEKB is a challenge with higher beam charge
and lower emittanceu Steady progress towards designed injection beam in steps
v Alignment: almost confident on the required precision (0.1-mm local, 0.3-mmglobal), need to maintain for longer termv Positron generator: another license test, need discharge analysis
v RF gun: following recommendations at review meetings

u Will install all of remaining equipment at summer 2017u Will balance between final beam quality and progressive operationu Will balance between particle physics and photon scienceu With some Phronesis we may enjoy beam commissioning

Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

15

Mt. Tsukuba

Thank you
SuperKEKB
dual rings
PF-ARPF600m Injector
Linac

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

K.Furukawa, KEK, b2gm, Oct.2016.

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Injector Linac Status

K.Furukawa, KEK, b2gm, Oct.2016.

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