rejuvenation of 7-gev superkekb injector linac · ipac18-furukawa-poster.pptx (読み取り専用)...

IrCe cathode

KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of flavor physics beyond the standard model of elementary particle physics. SuperKEKB energy-asymmetric electron and positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. The

electron beams will be generated by a new type of RF gun, that provides a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 µm to 10 µm in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The summary of the rejuvenation is reported.

High-current Low-emittance RF Gun

e– / e+ Injector rejuvenation with high-intensity and low-emittance beams 
towards 40-times higher luminosity, operating for Phase-II commissioning

Rejuvenation of 7-GeV SuperKEKB Injector Linac





Y. Enomoto, K. Furukawa, M. Akemoto, D. Arakawa, Y. Arakida, H. Ego, A. Enomoto, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, 


S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, 
S. Ohsawa, F. Qiu, I. Satake, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimura, T. Suwada, T. Takenaka, M. Tanaka, 


N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou 
High Energy Accelerator Research Organization (KEK), SOKENDAI, Tsukuba, Ibaraki, 305-0801, Japan

Thermionic gun

Primary RF gun

Secondary RF gun

Injector Linac

Balanced Schedule for Improvements / Stability

e –

e –

PF-AR6.5 GeV

PF2.5 GeV

Belle II

HER7 GeV

LER4 GeV

e – BT

e+ BT

SuperKEKB3 km

DampingRingLow emittanceRF-gun

High efficiencye+ generator

Injector Linac600 m e+

40x Luminosity

2x beam current

Beam from Injector and Storage CurrentSuperKEKB: 7 GeV e- 2600 mA

4 GeV e+ 3600 mAPF: 2.5 GeV e- 450 mAPF-AR: 6.5 GeV e- 60 mA

RF-Gun e- beamcommissioningat A,B-sector

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

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

damped e+ commiss.at 1→5 Qe+ = 1~4nCe- commiss.at A→5 Qe- = 1~4nC

: Electron: Positron: Low current electron

1 - 2 nCPhase2

1 nCPhase1

Location↓

Time →

Phase1: high emittance beam for vacuum scrubPhase2,3: low emittance beam for collision

Without Top-up

2 - 4 nCPhase3

Improved RF gun

Direct PF-AR BT

DR Commiss.

Beam Licensesin steps

Low Emittance

Beams

4+1 RingInjections

Low Emittance Injections

Positron generator and its shield

SuperKEKB Electron/Positron Complex

PF / PF-AR photon science

◆ Short-term in many groups◆ Stability intensive 


(Hates failures)◆ Deliberate scheduled maintenance◆ Invests on maintenance◆ Distance from users◆ Fixed procedures


Difficult to train operators

SuperKEKB particle physics

◆ Long-term and fixed users◆ Performance intensive 


(Integrated performance)◆ Minimum preventive maintenance◆ Invests on improvements◆ May share common goal with users◆ Everyday is new 


On-the-job training for operators

Typical Accelerator Units

Pulse-to-pulse modulation operation

Flux Concentrator

e+4 nC Injection e-

10 nCPrimary e-

Bridge Coils

beamhole

Pulsed Corrector Magnets

DCFocusingMagnets

PulsedFocusingMagnets Side view

Solenoid

LAS Accel. StructureSpoilerTarget

Virtual accelerators for simultaneous top-up injections Each VA with associated beam feedback loops

Newly developed 64 pulsed magnets

Synchronized Global Controls

High-performance Pulsed Magnets

Summary ◆ Injector linac has been rejuvenated

since 2010, and is close to its completion.◆ It successfully injected required

electrons and positrons in SuperKEKB phase 1 & 2 commissioning. ◆ It maintained light source injections

during rejuvenation.◆ It is expected to improve for Phase 3

commissioning.

Pulsed positron generator

QTWSC cavity

QTWSC cavity

ARC

e– (2.5GeV, 0.2nC)

e− Gun

ARC

e+ Target e+ (4GeV, 4nC)

e− Gun

PF Injection

SuperKEKB-LER Injection e– (3.5GeV, 10nC)

ARC

e– (7GeV, 5nC)

e− Gun

SuperKEKB-HER Injection

ARC

e– (6.5GeV, 0.2nC)

e− Gun

PF-AR Injection

Damping ring

Event-based Control System

Every 20 ms

F.B

F.B

F.B

F.B

F.B

F.B

F.B

F.B

High-current Positron Generator

Rejuvenated Injector Linac