Overview of Electron / Positron
Injector Linac Status
Kazuro Furukawa<kazuro.furukawa@kek.jp>

for Linac division

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

Linac Overview

Mission of electron/positron Injector in SuperKEKBu 40-times higher LuminosityvTwice larger storage beam Higher beam current at Linacv20-times higher collision rate with nano-beam scheme³  Low-emittance beam injection from Linac (20μm)³  Shorter storage lifetime( Higher Linac beam current)uLinac challengesvLow emittance e-40xLuminosity³ with high-charge RF-gunvLow emittance e+³ with damping ringvHigher e+ beam current

e+ efficiency³ with new capture sectionvEmittance preservation³ with precise beam controlv4+1 ring simultaneous injection
Linac Upgrade Status towards SuperKEKB

2x beamcurrent

RF-gunK.Furukawa, KEK, Mar.2013.

2

Review Items in 2012 and Reviewer’s Commentsu Linac disaster recoveryvEarthquake is a natural disaster, a Force Majeure. In view of themanpower shortage in the Linac and Storage Ring groups, thecommittee suggests that the management team look into timeline,milestones and resources, and revise the schedule accordingly.

u RF gun and low-emittance transportvAggressively pursue a demonstration of the QTW gun with LaB6
cathode and the full power laser.

u Positron sourcevCSR effects in the bunch compressor should be examined. A
protection scheme for the target should be developed at least
conceptually.
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

3

Linac Facility

Facility Upgrade

Ohsawa et al.
u Addition of electric power and cooling water is crucial for the upgradev However, the facility division starts the design only after the budget is securedv It was only approved in JFY2012 (the facility budget is different from the project one)u Basic schedulev Design JFY2012, Building JFY2013, Facility JFY2014v Should not affect PF and PF-AR operationv Not available during initial commissioning
high currentgun	
low emittanceRF gun	
3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)	BunchCompressor	

S-bandlinac	

e+ target &capture section	
Positron capture section
920 kVA, 900 lit/min

Linac Upgrade Status towards SuperKEKB

1.1 GeVDamping Ringcirc. 136 m	
Energy-spread
Compression System	
3TRF gun	

50 Hz (e+ or e-)pulse-by-pulse
mode switching 	

PF
2.5 GeV e0.1nC x 1	

LER

PF-AR
6.5 GeV e- 	

4.0 GeV e+ 4nC x 2	ECS	C-bandmodules	

Damping ring BT (LTR, RTL)
310 kVAHER 7.0 GeV e5nC x 2	Switch yard (3SY)
300 kVA, 460 lit/min

K.Furukawa, KEK, Mar.2013.

4

Girder Recovery and Alignment Higo et al.

u Re-constructing soft-structure girder into hard-structureu Alignment withv 120m and 480m long-baseline laser between girdersv Laser tracker within a girder (~10m)v Target: 0.1mm local / 0.3mm global alignment³ Several iterations necessary for low-emittance beam transportu Beam transport/acceleration test for 600m (Nov.2012)v For the first time after the earthquake

XYCharge
Beam along 600-m linac
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

5

Microwave Power Source UpgradeuPulsed power modulators

Michizono et al.

vNine compact modulators are introducedvShare the same basic design for klystron, flux
concentrator, and gun high voltageuFast LLRF controllers, power amplifiers, andLLRF monitorsvFor simultaneous injection and bucket selectionvPulse-to-pulse stability monitorv50Hz event-based synchronized controls

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

6

RF Gun for Low-emittance Electron Beam

RF Gun Development

Yoshida et al.

u Photo cathode : stability, longer life, efficiency

Ir5CevAt first LaB6, then Ir5Ce  5nC / bunchu Laser : higher power, pulse width controlvNd:YAG medium, LD excitation  ~1.5mJ / 30ps / pulse at 266nm
vPolarization control for slant irradiationvYb:YAG fiber laser is introducedu Cavity : better focusing field, higher gradientv DAW (Disk and washer) type cavity

DAWvDevelopment of quasi-travelling-wave side-coupled cavity as wellu Test standsv RFgun at A-1 is constructed with fiber laser for SuperKEKBv RFgun at 3-2 was used to inject into PF with proper synchronizationv Long-period demonstration will be performed
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

7Beam Acceleration Test (RF-gun)uStep-by-step beam testsv4.5nC 240m accelerationvFiber-laser-based RF-gunX
YCharge
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

8

Positron Capture for High-current Positron

Positron Generator Developmentu Flux concentrator

Kamitani et al.

v Collaborations with BINP and IHEPv Finalized optimization of field and mechanical designv Fabricated 1st version of 2nd generation, being testedu Large-aperture S-band (LAS)
cavity structurev Positron capture tracking simulationv L-band structure as backup
with co-linear loadu Magnet design and fabricationv Solenoid and pulsed steering and quadmagnet system

LASu Reliabilityv Strategy for failed component replacementv Acceleration gradient distribution andoptimization with backups
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

9

Beam Monitors: BPM and WS Suwada et al.
³ Limited performance with present 8-bit 10GS/s digitizers (oscilloscopes)u New BPM readout for precise orbit/emittance controlsvFast attenuator for 0.1-10nC (SuperKEKB, PF, PFAR) dynamic rangevHelical BSF (300MHz) for 2-bunch (96ns apart) readoutv16bit 250MS/s ADC, FPGA data processing BPM(18K12)
AD
ADC"ch.(1LSB=0.038mV)
v50Hz event-control synchronization(2012/2/7,")

60000"
50000"

1.8V
40000"
CH1"
30000"
20000"
10000"
0"200"

100ns
220"

240"

260"

280"

300" x"4nsuNew wire scanner readout was also developed
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 10

Dual-layer Controls

Single Machine, Multiple Virtual Accelerators (VAs)u Simultaneous injection, one of the VAs is active at a timeu Independent parameter set for each VA, ~200 parameters are switchedevery 20ms pulsee− Gun
ARCPF Injectione– (2.5GeV)

e− GunKEKB-LER Injection

ARC

Event-basedControl System

Primary e– (3.5GeV)

e+ (4GeV)

e+ Targete− GunARC

KEKB-HER Injectione– (7GeV)e− GunARC

Linac Upgrade Status towards SuperKEKB

PF-AR Injectione– (6.5GeV)

K.Furukawa, KEK, Mar.2013. 11

Dual-layer Controls

Example of Beam Mode Pattern : e+ 25Hz / e– 25Hzu Interleaved e+ and e-, dependency between pulses mostly decoupledu With bucket selection at the both DR and MRe− Gun
ARC
Primary e– (3.5GeV)

e+ (4GeV)

e+ Target

20ms

e− GunARCe– (7GeV)
20ms
e− GunARC
Primary e– (3.5GeV)

e+ (4GeV)

e+ Target

20ms

e− GunARCe– (7GeV)
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 12

u Preliminary Beam Tests in Autumn 2012v Beam test along 600-m Linacv for the first time after the earthquakev Latter half was tuned for PF/PFAR injectionv Alignment will be recovered by 2014XYChargev For energy spread optimizationv Longitudinal beam profile managementby photo-cathode RF-gun (30ps square shape)v and bunch compression at the middle of linac
are crucial

Beam along 600-m linac
R56=0³ Preliminary R56 control
was performed³ Design and measurementof dispersion function
with R56=0 and R56=-0.6

R56=-0.6
DesignLinac Upgrade Status towards SuperKEKB

Measurement
K.Furukawa, KEK, Mar.2013. 13

Schedule

Scheduleu Winter 2013 : DR switchyard / DR tunnel constructionu Spring 2013 : A1-RF-gun, Alignmentu Summer 2013 : Installation of many componentsv ECS, FC (gen.2), DC solenoids, Klystron modulators, WS, etcu Autumn 2013 : e– then e+ commissioning (limited current)vHalf Linac: PF injection, Day: construction, Night: commissioningu Spring 2014 : Pulsed steering, Alignmentu Summer 2014 : Installation of additional componentsv Cooling water, FC (gen.3), BPM, Pulsed magnets, New PFAR BT, etcu Autumn 2014 : Linac Commissioningu Winter 2015 : MR (then DR) injection commissioningu …
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 14

Summaryu Much progress in disaster recovery and construction.
u Still expecting many challenging items to overcomeu Many items are connected with beam emittance and energy spreadmanagementu Injector should start at first !
u RF Gun (M. Yoshida)u Alignment and Support (T. Higo)u Positron Source (T. Kamitani)u Flux Concentrator Modulator Development (M. Akemoto)u Commissioning of Electron Beam (M. Satoh)u New Transport Line for PF-AR (H. Takaki)u Construction status of the damping ring and the beam transport (N. Iida)u Control (T. Nakamura)
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 15

Thank you

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 16

Linac Overview

Linac Upgrade for SuperKEKB
u Higher Injection Beam Currentv To Meet the larger stored beam current and shorter beam lifetime in the ringv 4~8-times larger bunch current for electron and positronu Lower-emittance Injection Beamv To meet nano-beam scheme in the ringv Positron with a damping ring, Electron with a photo-cathode RF gunv Emittance preservation by alignment and beam instrumentationu Quasi-simultaneous injections into 4 storage ringsv SuperKEKB e–/e+ rings, and light sources of PF and PF-ARv Improvements to beam instrumentation, low-level RF, controls, timing, etc
SuperKEKB injector Linac	

high currentgun	
low emittanceRF gun	

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

S-bandlinac	

e+ target &capture section	
Linac Upgrade Status towards SuperKEKB

1.1 GeV
Damping Ringcirc. 136 m	
Energy-spread
Compression System	3T
RF gun	50 Hz (e+ or e-)pulse-by-pulse
mode switching 	

PF
2.5 GeV e0.1nC x 1	LERPF-AR
6.5 GeV e- 	4.0 GeV e+ 4nC x 2	ECS	C-bandmodules	

HER 7.0 GeV e5nC x 2	K.Furukawa, KEK, Mar.2013. 17

Linac Upgrade for SuperKEKBPFBJ-arc
1.5 GeVA

Primary e– for e+
3.2 GeV, 10nC x 2
Bunch
Compression

C1

Bunch
Compression

New e+Capture
with FC

2

2.5 GeV
0.1nC x 1

1.1 GeVe+ damping ring

New RF-gun
5 nC for e–, 10nC for e+
IrCe cathode, Fiberlaser, DAW cavity

SY2

EnergyCompression

3

EnergySY3 Compression

45PF-AR
6.5 GeV
5nCLER

4.0 GeV e+
4nC x 2

HER7.0 GeV
5nC x 220 umu As a high-field (several Tesla) pulsed solenoid for the positron source of theSuperKEKB injector, KEK is going to fabricate a SLAC-type flux concentrator.
u Technical advices from the IHEP experts and design information by the IHEP
drawings are quite useful in the development.

Flux
Concentrator

electronbeam

Linac Upgrade Status towards SuperKEKB

positronbeamK.Furukawa, KEK, Mar.2013.