Achievement of 200,000 Hours of Operation
at KEK 7-GeV Electron 4-GeV Positron Injector Linac
K. Furukawa, M. Akemoto, D. Arakawa, Y. Arakida, H. Ego, Y. Enomoto, T. Higo, H. Honma, N. Iida, K. Kakihara,
T. Kamitani, H. Katagiri, M. Kawamura, S. Matsumoto, T. Matsumoto, H. Matsushita, K. Mikawa, T. Miura,
F. Miyahara, H. Nakajima, T. Natsui, Y. Ogawa, S. Ohsawa, Y. Okayasu, T. Oogoe, M.A. Rehman,
I. Satake, M. Satoh, Y. Seimiya, T. Shidara, A. Shirakawa, H. Someya, T. Suwada, M. Tanaka,D. Wang, Y. Yano, K. Yokoyama, M. Yoshida, T. Yoshimoto, R. Zhang, X. Zhou, Y. Bando,High Energy Accelerator Research Organization (KEK), SOKENDAI, Tsukuba, Ibaraki, 305-0801, JapanKEK electron positron injector LINAC initiated the injection operation into
Photon Factory (PF) light source in 1982. Since then for 39 years, it has
served for multiple projects, namely, TRISTAN, PF-AR, KEKB, and SuperKEKB.
Its total operation time has accumulated 200 thousand hours on May 7, 2020.
We are extremely proud of the achievement following continuous efforts by ourseniors. The construction of the injector LINAC started in 1978, and it wascommissioned for PF with 2.5 GeV electron in 1982. In parallel, the positron
generator linac was constructed for the TRISTAN collider project. The slow

positron facility was also commissioned in 1992. After the KEKB asymmetricenergy collider project was commissioned in 1998 with direct energy injections,the techniques such as two-bunch acceleration and simultaneous injection
were developed. As the soft structure design of the LINAC was too weakagainst the great east Japan earthquake, it took three years to recover. Thenthe construction and commissioning for the SuperKEKB project went on, andthe simultaneous top-up injection into four storage rings contributes to the bothelementary particle physics and photon science.

KEK e– / e+ injector LINAC has been contributing to particle physics and photon scienceand has established 200 k operation hours in 38 years in 2020
Projects Operated by LINAC

Injection Energies and Operation Periods
JFY 1970
1980
1990
2000
2010
2020
Exp. Energy
8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 90Project

Injection Energy

Photon Factory

2.5 GeV

2.5 GeV

TRISTAN

2.5 GeV

32 GeV

Slow Positron

2.5 GeV - 55 MeV

0.1 - 35 keV

KEKB

8 / 3.5 GeV

8 / 3.5 GeV

PF-AR

2.5 GeV - 6.5 GeV

5 - 6.5 GeVSuperKEKB

7 / 4 GeV

7 / 4 GeV

Construct.

Injection Operation
Construct.

Injection Operation
Operation

Operation

Construct.

Injection Operation
Injection Operation
Construction

The injector LINAC has realized a number of projects for particle physics and photon science.

Accelerator Configurations

Injection2016 –1999 – 2010

Belle II

LER
4 GeV

Beam from Injector and Storage Current
SuperKEKB:
7 GeV e2000 mA
4 GeV e+2800 mA
PF:
2.5 GeV e450 mA
PF-AR:
6.5 GeV e60 mA

SuperKEKB
3 km

1986 – 1994

HER
7 GeV

PF-AR
6.5 GeVe– BTe+ BT

High efficiency
e+ generator

e–e+Injector Linac
700 m

PF
2.5 GeV

Damping
Ring

Rejuvenated Injector LINAC
B

A

New RF gun 5 nC
Thermionic gun 10 nC

1.1 GeV
e+ damping ring

J-arc
Slow Positron
1.5 GeV
EnergyBunchPrimary electron
New PositronCompression Compression
Capture Section
2.9 GeV, 10nC x 2
Bunch
Compression

C123Low emittance
RF-gunPF
2.5 GeV
0.2nC x 1

LER

Energy4.0 GeV
Compression 4nC x 2

45PF-AR
6.5 GeV
0.2nC x 1

HER
7.0 GeV
4nC x 220 um

Additional accelerator components have been designed and introduced to meet thebeam property requirements for each project.

Injection Progress in KEKB
Daily Operation Status
Red: Beam current (e–, e+)
Yellow: Collision luminosity
Green: Integrated luminosity
Pale blue: Lifetime (e–, e+)Purple: Vacuum (e–, e+)Simultaneous Top-up Injection
Event-based
Control SystemEvery
20 msF.B
e− GunF.B

PF InjectionARC

e– (2.5GeV, 0.2nC)

F.B

May.2000e− GunARCApr.2003
2 bunchesin a pulse

Feb.2005
Continuousinjection

Dec.2008
3-ring simultaneous top-up
injection with crab cavities

New technologies have been developed at LINAC
to improve the experimental performance.

Damping ring

SuperKEKB-LER Injection

F.B

e– (3.5GeV, 10nC)

F.B

e+ Targete+ (4GeV, 4nC)

e− GunARC

SuperKEKB-HER Injection

F.B
ARC

F.B

◆ The continuous operation of the electron-positron injector has supported thee– (7GeV, 4nC)

e− GunPF-AR Injection

SummaryF.B
e– (6.5GeV, 0.2nC)

The single LINAC behaves as four virtual injectors
by switching beam properties at 50 Hz.

history of advanced research at KEK.
◆ At 8:50 a.m. on May 7, 2020, the injector LINAC had accumulated its operationof 200,000 hours successfully, while continuing the simultaneous top-up
injections for multiple fields of photon science and particle physics.