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10MWKlystron

1.5m RF-Deflector

SuperKEKB injector upgrade for high charge and low emittance electron beam.

M. Yoshida, N. Iida, Y. Ogawa, T. Osawa, Z. Lei T. Natsui, M. Sato, H. Sugimoto, X. ZhouHigh Energy Accelerator Organization (KEK)

Present projected emittance measurement

Emittance measurement at 5-sectorAB

1C 2 3 4 5

PF InjectorWeak lens

0

100

200

300

400

500

600

0 20 40 60 80 100 120C to sector Q-magnet[ % ]２

Emittance (m

m m

rad)

Project emittance using weak lens

screen

sin2

/

10 , 2.856 , 10 ,

deflector RFscreen deflector screen deflector screen

beam

x screen screen

deflector deflector RFx

screen beam

deflector RF deflect

eV tx

E

eV tx

E

V MV f GHz t ps

screen

screen

10

/ 3

22 , 11.424 , 10 , 10

/ 27

or

x

deflector RF deflector

x

m

x

V MV f GHz t ps m

x

zRF-Deflector

x

y

( ) ( )y y yt t

t

Transverse Wakefield Measurement => Initial offsetusing X-band RF-Deflector

Beam diagnostic station In third switch yard

Input Power : 10MWDeflecting Voltage : 22 MV

RF-Deflectordeveloped by SLAC

for LER4.0 GeV 4nC x 2y < 6 mm mradfor HER

7.0 GeV 5nC x 2y < 20 mm mrad

Longer bunch can reduce space charge effect inside RF-Gun and also CSR at J-ARC.

Due to mis-alignment:- Dispersion - Short range wakefield

AB

C 1 2 3 4 5Target @1-43.5 GeV 10nC x 2

1.1GeV@DR

ECS

RF-Gun5-10nC

C-band

ECSBCS

PFJ-ARC

Beam diagnostic station

KEKB obtained(e+ / e-)

SuperKEKB 　required 　 (e+ / e-)

Beam energy 3.5 GeV / 8.0 GeV 4.0 GeV / 7.0 GeV

Bunch charge e- 　 e+ / e-10 1.0 nC / 1.0 nC

e- e+ / e-10 4.0 nC / 5.0 nC

Beam emittance (g)[1] 2100 mm / 300 mm 6 mm / 20 mm

High charge low emittance is required for SuperKEKB.

RF-Gun

40 nC

RF-Gun

- High charge & low emittance RF-Gun- Cavity with electric focusing field- Disk and Washer 　 => 3-2- Quasi Traveling Wave => A-1

- Long life cathode QE : 10-4

- LaB6, Ir5Ce at room temperature- High power laser > mJ @ 266nm- Nd doped solid state laser- Yb doped fiber & solid state laser

- Beam transport- Alignment- Emittance preservation- Beam diagnostics

3-2A-1

C-1

Linac beam line

Injection beam line on the angle

3-2 RF-Gun (from Sep 2011) :- PF/PF-AR Injection during SuperKEKB construction phase - 5nC test stand for SuperKEKB

High charge & low emittance RF-Gun :A-1 RF-Gun (will install until Sep 2012) - Cavity : Higher electric focusing field

=> Quasi traveling wave

- Cathode -Ir5Ce at room temperature => QE :10-4

- LaB6 or Ir5Ce with heater => QE :10-3

- Laser : Higher power & stable laser=> Yb based chirped pulse amplification

Present beam statue

Cavity : Disk and Washer

Laser : Nd doped solid state laser

- Nd:YAG 5-stage amplifier

- Nd:YVO4 + SESAM passive modelock oscillatorDAW-type RF gun (90 MV/m, 5 mm-mrad, 3.2 MeV)

BNL-type RF gun (120 MV/m, 11.0 mm-mrad, 5.5 MeV)

Quasi traveling wave side couple RF gun

(100 MV/m, 6mm-mrad, 13.5 MeV)

BNL (3.8 mm)

QTW (0.2 mm)

DAW (1.7 mm) Beam Size

Cathode : LaB6 => Ir5Ce

Cathode rod

Ir5Ce Photocathode

Simulation of projected emittance

σz=0.75mmσa=0.3mm

σz=2 mmσa=0.3mm

σz=0.75mmσa=0.1mm

σz=2 mmσa=0.1mm

1st order

2nd order

Projected emittance dilution due to transverse wakefield

Beam tracking simulation :Intial emittance : 6 mm mradMis-alignment : = 0.3mm Initial offset

Initial offset scan to compensate transverse wakefield

Wire scanner should install more.AB

1C 2 3 4 5

J-ARC PF Injection

0

100

200

300

400

500

600

700

800

B C 5Sector

gy [

mm

mra

d]

0.5nC1nC3nC5nC1.0nC 3.0nC 5.0nC 7.0nC

0

200

400

600

800

1000

1200

1400

B C 5Sector

gx [

mm

mra

d]

0.5nC1nC3nC5nC1.0nC 3.0nC 5.0nC 7.0nC

Existing wire scanner

DC-Gun

Consideration of bunch compression using J-ARC

Beam tracking simulation

Pulse Q-magnet & pulse steering

Emittance preservation :