Beam Injection Operation for Particle Physics and Photon Science
Experiments with Pulse-to-Pulse Beam Modulation
K. Furukawa and M. Satoh,High Energy Accelerator Research Organization (KEK), SOKENDAI, Tsukuba, Ibaraki, 305-0801, JapanThe electron and positron accelerator complex at KEK offers uniqueexperimental opportunities in the fields of elementary particle physics withSuperKEKB collider and photon science with two light sources. In order tomaximize the experimental performances at those facilities the injector linac
employs pulse-to-pulse modulation at 50 Hz, injecting beams with diverse properties.
The event-based control system effectively manages different beam configurations.
This injection scheme was initially designed 15 years ago and has been in fulloperation since 2019. Over the years, a number of enhancements have beenimplemented. As the event-based controls are tightly coupled with microwave
systems, machine protection systems and so on, their modifications require
meticulous planning. However, the diverse requirements from particle physics andphoton science, stemming from the distinct nature of those experiments, often
necessitate patient negotiation to meet the demands of both fields.
Thispresentation discusses those operational aspects of the multidisciplinary facility.

KEK e– / e+ injector LINAC delivers multi-disciplinary beam injections for 4 + 1 storage rings of light sources
and a particle physics collider even with higher beam charge and lower beam emittance
Injector LINAC Configuration

BAPF
2.5 GeV
0.2nC x 1

1.1 GeVe+ damping ring

New RF gun 5 nC
Thermionic gun 10 nC

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

1C23

Simultaneous Top-up Injections into 4 + 1 Rings
Low emittance
RF-gune–Event-based
Control System

Improved SuperKEKB performance by 237%
Four virtual injectors

F.B
e− GunInjector Linace–e– (2.5GeV, 0.2nC)

F.B

e+ BT

PF-AR
6.5 GeVe – BT

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

17.54 /pb in 5.15 hr(5 fills)
on May.6F.B

PF Injection

ARCe+700 m
High efficiency
e+ generator

4PF-AR
6.5 GeV0.2nC x 1Every20 ms

2x beamcurrentPF
2.5 GeV

5HER
7.0 GeV
4nC x 220 um

e− Gun
ARCHER
7 GeV

Damping ring

F.B

SuperKEKB-LER Injection

41.64 /pb in 5.15 hr(top-up)on May.16e– (3.5GeV, 10nC)

F.B

e+ Targete+ (4GeV, 4nC)

e− GunSuperKEKB

ARCSuperKEKB-HER Injection

237%
improvement

F.B

3 km

LER
4 GeV

Belle II

F.B

e– (7GeV, 4nC)
e− GunARC

30x
Luminosity

Electron/positron machine complex at KEK

F.B

PF-AR Injectione– (6.5GeV, 0.2nC)

Historical Linac Beam Deliveries
Injection Energy

Photon Factory

2.5 GeV

TRISTAN19801990200020102020
JFY 1970
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 9 0 1 2 3
2.5 GeV

Construct.

Operation

Construct.

Injection Operation

2.5 GeV - 6.5 GeV 5 - 6.5 GeV

PF-ARSuperKEKB

7 / 4 GeVTRISTANKEKB

Injection Operation

7 / 4 GeV

Construction

Injection

7,000

5,000

54,00043,00032,00021,000101982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022

Fiscal year

◆Long-term and fixed single user group◆Performance intensive◆Stability intensive(Integral performance during a year)(Hates failures)

Required Beam PerformanceStage

KEKB (final)

Beam

e+

e–e+e–e+e–e+e–e+e–

EnergyStoredcurrent
Life time(min.)

3.5 GeV

8.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

4.0 GeV

7.0 GeV

1.6 A

1.1 A

1.0 A

1.0 A

––

1.8 A

1.3 A

3.6 A

2.6 A

150

200100100––––66primary e- 10◆Meticulous scheduled maintenance◆Minimum preventive maintenance◆Invests on improvements◆Invests on maintenance◆Formal common objective between users◆May share common goal with the user

◆Fixed procedures◆Everyday is new

Difficult to train operators against failures

6Injection stop

SuperKEKB particle physics◆Short-term in many user groups

70Dual Disciplinary Beam Injection
PF / PF-AR photon science

SuperKEKB

Operation hour

6,000

Operation

8 / 3.5 GeV

8Partial failure

Injection Operation

Slow Positron 2.5 GeV - 55 MeV 0.1 - 35 keV
8 / 3.5 GeV8,000

Injection Operation

Construct.

32 GeV

2.5 GeV

KEKB

Statistics of the Injector Linac Operation

Operation (hour)

Project

Beam Injection Statistics

On-the-job training for operators

Bunch charge
(nC)
Norm.
Emittance

Phase-I (achieved)

Phase-II (achieved)

Phase-III (interim)

primary e- 8

→1

1

→ 0.4

1400

310

1000

Phase-III (final)

primary e- 10

10.5

1200/40130(gbe) (mrad)

2

2

4

150/30100/40100/1540/20(Hor./Ver.)(Hor./Ver.)(Hor./Ver.)(Hor./Ver.)→4150(Hor./Ver.)

Energyspread

0.13%

0.13%

0.50%

0.50%

0.16%

0.10%0.16%

0.10%

0.16%

0.07%

Bunch / Pulse

2222222222

Repetitionrate

50 Hz

25 Hz

25 Hz

Simultaneous
top-upinjection(PPM)

3 rings(LER, HER, PF)

No top-up

Partially

50 Hz

50 Hz

4+1 rings (LER, HER, DR, 4+1 rings (LER, HER, DR,PF, PF-AR)
PF, PF-AR)◆Injector linac arbitrates between downstream accelerators with incompatible disciplines

for long-term plans, yearly maintenance and improvements, and daily beam deliveries

Summary◆ KEK injector LINAC continues simultaneous top-up

injections to support the both photon science andparticle physics experiments.
Top-up injections for dual disciplines◆ It often carries administrative and operational

negotiations to a successful conclusion to enable
short-term and long-term optimizations and toenhance performances for the both disciplines.

Rates (%)

Damping
Ring

LER

Energy4.0 GeV
Compression 4nC x 2