Dual Disciplinary Beam Injections forParticle Physics and Photon Science Experiments
K. Furukawa and M. Satoh,High Energy Accelerator Research Organization (KEK), SOKENDAI, Tsukuba, Ibaraki, 305-0801, JapanThe electron and positron accelerator complex at KEK provides
experimental opportunities for elementary particle physics with SuperKEKB
collider and photon science with two light sources. In order to maximize theexperimental performances at those facilities the injector linac delivers beams
with widely differing properties in pulse-to-pulse modulation at 50 Hz. Different
beam flavors are managed with the event-based control system. This injection

scheme has been fully employed since 2019. Many further improvements
were introduced every year. As the event-based controls are tightly coupledwith RF, machine protection systems and so on, their modifications needdeliberate plan. However, the requirements from particle physics and photon
science are very different because of the nature of experimental users. Patient
arbitration is often required to satisfy users from those distinct fields.

KEK e– / e+ injector LINAC delivers multi-disciplinary beam injections for 5 storage rings of light sources
and high energy collider even with higher beam charge and lower beam emittance
Injector LINAC Configuration

BAPF
2.5 GeV
0.2nC x 1

1.1 GeV
e+ 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 Injections into 5 Rings
Damping
Ring

Low emittance
RF-gune–High efficiency
e+ generator

PF-AR
6.5 GeV
0.2nC x 1

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

PF Injection

ARCe–HER
7.0 GeV
4nC x 220 um
Improved SuperKEKB performance by 237%

F.B

e+700 m5Every20 ms

e− GunInjector Linac

4Event-based
Control System

2x beamcurrentPF
2.5 GeV

LER
Energy4.0 GeV
Compression 4nC x 2

e– (2.5GeV, 0.2nC)

F.B

e+ BT

PF-AR
6.5 GeVe – BTe− Gun
ARC

HER
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− GunBeam 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

ARCSuperKEKB-HER Injection

237%
improvement

F.B

3 km

LER
4 GeV

Belle II

F.B
ARC

30x
Luminosity

Electron/positron machine complex at KEKe– (7GeV, 4nC)
e− GunPF-AR Injection

F.B
e– (6.5GeV, 0.2nC)

Dual Disciplinary Beam Injection
SuperKEKB particle physics

PF / PF-AR photon science

Required Beam Performance◆Long-term and fixed single user group◆Short-term in many user groups

Stage◆Performance intensive◆Stability intensive(Integral performance during a year)(Hates failures)◆Deliberate scheduled maintenance

KEKB (final)

Phase-II (achieved)

Phase-III (interim)

Phase-III (final)

Beame+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

200

100100––––66

primary e- 10

Bunch charge(nC)◆Minimum preventive maintenancePhase-I (achieved)

Norm.
Emittance

primary e- 8

→1

1→ 0.4

1400

310

1000

primary e- 10

10.5

1200/4013022

4

150/30100/40100/1540/20(Hor./Ver.)(Hor./Ver.)(Hor./Ver.)(Hor./Ver.)→4150◆Invests on improvements(gbe) (mrad)
Energyspread

0.13%

0.13%

0.50%

0.50%

0.16%

0.10%

0.16%

0.10%

0.16%

0.07%

◆Formal common objective between users◆May share common goal with the user

Bunch / Pulse

2222222222Repetitionrate

50 Hz

25 Hz

25 Hz◆Fixed procedures◆Everyday is new

Simultaneous
top-upinjection(PPM)

3 rings(LER, HER, PF)

No top-up

Partially◆Invests on maintenanceDifficult to train operators against failures(Hor./Ver.)

50 Hz

50 Hz

4+1 rings (LER, HER, DR, 4+1 rings (LER, HER, DR,PF, PF-AR)
PF, PF-AR)

On-the-job training for operators◆Injector linac arbitrates between downstream accelerators with incompatible disciplines

for long-term plans, yearly maintenance and improvements, and daily beam deliveries◆Stability intensiveSummary◆ KEK injector LINAC continues simultaneous top-up

injections to support the both photon science andparticle physics rings.

Top-up injections for dual disciplines◆ Administrative and operational negotiations areoften necessary to enable short-term and long-term
optimizations in order to enhance performances forthe both disciplines.

Even Further Upgrade Categories

RF gunPulsed magnets/kickers

Positron capture section

High precision movers

Accelerating structure

PCB capacitor renewal

New energy compressor