Injector Linac Status
Masanori Satoh (KEK)on behalf of Injector Linac Group

Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

1

Contents• Outline• e- beam status• e+ beam status• Other subsystems• Upgrade work during summer shutdown FY2021• Summary

Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 20212

Outline (I)• Injector Linac [P. 5]

Outline• Injector linac provides positron beam to LER via DR and electron beam to HER/two light sources(PF, PF-AR).
• Two electron guns:• Photocathode rf gun and thermal gun are utilized for HER and LER/two light sources
injections, respectively. At the injector beam line, two different guns are situated in the double
decker configuration [P. 6].
• Maximum beam repetition is 50 Hz (sum of two guns). All klystrons are always running in 50
Hz for keeping the constant temperature of cooling water.
• Both guns can generate two bunches in one rf pulse for HER/LER injection beam with the intervalof 96 ns.

• Simultaneous top up injection• Simultaneous top up injection to 4 rings has been successfully conducted since May 2018. [P. 7]• Pulse-to-pulse beam control can be performed by changing the low level rf phase/timing (energy,
energy spread), pulsed magnet settings (quad, steering, switching bend) with the event basedtiming system (3 event generators (EVGs) and 45 event receivers (EVRs)). [P. 8]
Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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• Beam monitors

Outline (II)Outline• BPM (x103)• BPM can perform non destructive beam position measurement. Special module based on the
VME and EVR beam position measurement precision is less than 10 mm. All beam shot data
(50 Hz) can be measured and stored for the postmortem analysis.
• Profile monitor (x104)• Profile monitors are utilized for the destructive beam shape measurement with the material of
Al2O3/CrO3 (AF995R, Demarquest Co.) (t: 1 mm, 0.1 mm) and YAG:Ce (t: 0.1 mm). Optics
measurement is conducted by Q-scan method using YAG profile monitor. Linux-based PLC is
used as controller.
• Wire scanner (x2)
• They are situated in SectorA, B, C, 2, 3, 5 for the optics measurement. The diameter oftungsten wire is 100 mm.
• Streak camera (x2)
• They are situated in SectorA and Sector3 for the bunch length measurement. One in SectorC
was obsoleted because of the fire accident in 2019.

• RF monitors• RF monitors (x61) can measure rf amplitude/phase of the Klystron output, SLED output,
accelerating structure output. All shots of average and peak values are stored for postmortem
Masanori Satoh(KEK)
KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021
analysis.

4Outline

Injector Linac
60 klystron units
240 accelerating structures (S-band 2-m-long)・Two electron sources:
RF gun: HER injection
thermal gun: LER, PF, PF-AR
・Sector 3-5:
All magnets are pulsed magnets.
Continuous orbit feedback

8 Sectors (A-C,1-5)
Energy Knob

1.1 GeV e+
Damping Ring

Thermionic gun
PhotocathodeRF gunJ-ARC
1.5 GeV

B

A

BCS
ECS

C

1

2

3

e+
e+ capture section
target

4

5

PF

ECS

PF-AR

LER

chicaneEnergy KnobHER
HER 7GeV
PF-AR 6.5 or 5 GeV

Acceleration
4.2 GeV

ee+ target

LER 4 GeV e+Stand-byDeceleration

1.1 GeVe+

PF 2.5 GeV

Acceleration

1.5 GeVC

Masanori Satoh (KEK)

1

2

3

4

5
5

Beam energy variationKEKB
for eachbeam
along
the6, 2021
beam line after the J-ARC
Accelerator
ReviewmodeCommittee,
Sept. 1-2,

5

Pulse to pulse beam switching:rf e- gun/thermionic e- gun
In injector section(double decker beam line)

Thermionic DC e- gun (GU_AT)

Outlinew/ 2 subharmonic bunchers (114 MHz, 571 MHz) and 2
bunchers.

・e+ production e-: 10 nC (for LER injection)・e- study/HER injection: 1 nC
・PF injection: 0.1 - 0.3 nC
・PF-AR injection: 0.1 - 0.3 nC

RF e- gun
（GR_A1 for HER injection）

Pulsed bend
Schematic side view

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

6

Simultaneous top up injection to 4 rings- stored current and linac beam orbit -Stored current (1 day)OutlineLinac/BT beam orbit
HER

LER

x
(mm)
y
(mm)

I (nC)PF-AR

Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

PF

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Beam Injection Pattern Generation
for simultaneous top up injection

Outline• Beam repetition rate is determined by demand from each ring.
• Priority can be defined.

Beam mode
KBE: SuperKEKB e- (HER)
KBP: SuperKEKB e+ (LER)
QFE: PFARE:
PF-AR
KEKB Accelerator Review Committee, Sept. 1-2,
6, 2021

Beam repetition rate management foreach beam injection mode.

Masanori Satoh (KEK)8

Parameters
Stage

KEKB
(achievement)

SuperKEKB
Phase-I(achievement)

Phase-III

Phase-II(achievement)

OutlinePhase-III

Phase-III

Summer’19

Summer’20(achievement)(achievement)(achievement)

Summer’21

Phase-III (final)

Beam

e+

e–

e+

e–

e+

e–

e+

e–

e+

e–

e+

e–

e+

e–

Energy (GeV)

3.5

8.0

4.0

7.0

4.0

7.0

4.0

7.0

4.0

7.0

4.0

7.0

4.0

7.0

Stored current
(A)

1.6

1.1

1.0

1.0

1.0

1.0

0.83

0.94

0.712

0.607

0.790

0.687

3.6

2.6

Life time (min.)

150

200

100

100

50

100

20
(typ.)

70(typ.)

12

21

9

22

6

6

primary e- 10

Bunch charge
(nC)
Norm.
Emittance

primary e- 8

primary e- 10

1
→1

1

1400

310

1.6

3.6

1.35

3.5

1.6

3

→ 0.4

1000

130

200/5
(Hor./Ver.)

200/40

120/6

54/67

100/2

41/45

2.5

2

→

4

4

100/1540/20(Hor./Ver.)(Hor./Ver.)

100/60 100/80(gbe) (mmrad)
Energy spread

0.13%

0.13%

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

0.16%

0.07%

Bunch/Pulse

2

2

2

2

2

2

1

1

1

1

2

1

2

2

Repetition rate
(Hz)

50

25

25

Simultaneous
top-upinjection

3 rings(LER, HER, PF)

No top-up

Partially

50(LER+PF+PF-AR< 25 Hz)50(LER+PF+PF-AR <25 Hz)

50 Hz

50 Hz

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

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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e- beam status

KEKB Accelerator Review Committee, Sept. 1-2, 6, 202110

e- beam status (I)e- beam status• Thermal e- gun• Thermal gun provides e- beam with bunch charge of around 10 nC for positron production (LER
injection) and of around 0.3 nC for light sources. Two subharmonic bunchers (114 MHz, 571 MHz),pre-buncher, and buncher can generate the single bunched e- beam with the bunch length of about 5
ps (0.3 nC)/10 ps (10 nC) in FWHM.
• It has worked through run 2020c to 20201b without any significant troubles.

• RF e- gun• Photocathode rf gun is utilized for generating the low emittance e-. Electron beam from rf gun isdirectly delivered to HER ring without DR. The system comprises of quasi travelling wave (QTW)
type cavity, Ir7Ce2 photocathode, and laser system. Two laser system is in operation (1st laser line
and 2nd laser line). 1st laser line is utilized for daily operation, and 2nd line is backup and also
cathode laser cleaning system for recovering the quantum efficiency of photocathode. Both laserlines can be simultaneously operated for obtaining higher bunch charged e- beam. [P. 14, P. 15]• Diffractive optical element (DOE) has been installed in 1st laser line after run 2020b for reshaping
the transverse laser profile (flat-top distribution). After run 2020c, it can help obtaining the low
emittance beam w/ high bunch charge by mitigating space charge effect and decreasing beam jitter.
[P. 16]

Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 202111

e- beam status (II)e- beam status• RF e- gun (cont’d)• DOE was not installed for 2nd laser line in the summer shutdown in FY2020 because of the lack of
installation space. However during summer shutdown in FY2021, Another DOE will be installed
also in 2nd laser line by remodeling the laser line configuration.
• At the beginning of run 2021a, we prepared the electron beam with bunch charge of 2 nC at BT.
Best normalized emittance achieve 20 mm in the both directions. Bunch charge is still smaller than
the final target of 4 nC, however, emittance reaches the design value at BT1.
• At the end of March, the output power of amplifier module #2 used in 1 st laser line decreased.
During investigating the amplifier module, large discharge occurred in the rf gun cavity because themodule checked was done without turning off the beam and bunch charge feedback system. During
checking work, 1st laser line power and bunch charge from rf gun decreased. And then, the 2nd laser(squeezed laser for photocathode cleaning) output power was increased by bunch charge feedback
system for recovering the bunch charge of e- beam. In this process, discharge occurred inside thecavity and . After this event, cavity power was decreased for prevent the frequent discharge. [P. 17]

Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 202112• e- beam quality

e- beam status (III)e- beam status• Emittance measurement by multiple wire scanner has been continuously conducted especially at
SectorB and BT. Some measurement results show the good emittance, however, the issue is keeping
the low emittance beam condition as long as possible. [P. 18]• In Sector3-5, orbit feedback can continuously stabilize the e- beam position with 24 pulsed steering
magnets in both the horizontal and vertical planes. Emittance deterioration could be caused in theregion between SectorC and Sector3. Because of this, expanding the orbit feedback is issue forkeeping the low emittance. Additional pulsed steering magnets are installed at Sector2 (alsoSectorA, C) in summer maintenance FY2021. Moreover, some power supplies of existing pulsed
steering magnets are replaced by new one (doubled maximum output current) in Sector1 and JARC.
• Measured emittance of e- 2nd bunch shows large value in comparison with one of 1st bunch.
Injection efficiency of 2nd bunch is also low, and two bunch injection operation of e- beam was notestablished in run 2021a, b (successful in run 2020b). This reason could be the short rf pulse width(fed into rf gun cavity) since the rf pulse width was shortened from 1000 ns to 850 ns to avoid
frequent discharge. In run 2021c, we will apply the nominal rf pulse width of 1000 ns after careful
rf conditioning in the startup stage of autumn operation [P. 19]

Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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Low emittance photocathode rf e- gunRF e- gunIr7Ce2 cathodee- beam status

Laser system• Photocathode: Ir7Ce2• Cavity: QTWSC (Quasi Travelling Wave Side Coupler)– Strong focusing electric fieldshort drift space
Secondary RF gun
for test and backup

M. Yoshida et al.

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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Best emittancee(2 nC)～20 mm (BT#1)•

e- beam status

Hybrid laser system for rf e- gun

Yb doped fiber and Nd:YAG DPSS module Amplifier

nx,nxyGoal: enx,nxy (4 nC)～40/20 (H/V) mｍ)

•
•
•
•

Output Power in 1st line:ω (1064 nm): 32 mJ
2ω ( 532 nm): 11 mJ
4ω ( 266 nm): 1.2 mJ

1st laser
2nd laser

Laser roomon theground virtualKLY Gallery

cathodediagnosticsLaser line to RFGun
TunnelRF-GunR. Zhan, X. Zhou et al.

Optics layout
inthe Review
tunnel
KEKB15
Accelerator
Committee, Sept. 1-2, 6, 2021

Laser transport line

15

DOE for reshaping of laser spatial distribution
2019.06 without DOE & beam position sensor

H 2σ: 48.04±0.51, V 2σ: 46.08±0.69

Pointing stability
can be improved.

e- beam status

2021.06 with DOE & beam position sensor

H 2σ: 24.30±3.06, V 2σ: 10.08±0.46

DOE (diffractive optical element) in 1st laser line:
Laser beam homogenizer for low emittancebeam w/ high intensity bunch charge.

DOE is installed in vacuum
chamber filled with Argon gas.

world first DOE application in UV laser
Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

16

e- bunch charge history (2020a to 2021b)

e- beam status(from rf gun)(BT)
2020a,b2020c

2021a,bdischarge

KEKB Accelerator Review Committee, Sept. 1-2, 6, 202117

e- emittance history in run 2021a, b at SectorB and BT1

e- beam status

SectorB••

Orbit feedback can stabilize the e- beam orbit
through Sector3-5.
At upstream Sector, there are not enoughnumber of pulsed steering magnets for orbit
feedback. For keeping the beam orbit
upstream, additional pulsed steering magnets
are installed in summer shutdown FY2021.

BT1

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021
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18

e- beam status

2nd bunch of e- beam: deteriorated emittance
Emittance measured at BT1・2nd bunch emittance of e- beam is large incomparison with one of 1st bunch. It shows
the low injection efficiency.

1st bunchHor.

1st bunch

2nd bunch

Horizontal: gex [mm]16.4±2.045.9±3.6

Vertical: gey [mm]9.6±1.867.7±6.5

2nd bunch

45 deg.

large beam sizeVer.

A wireC wireA wireC wireB wireD wireB wireD wiree- beam profile measured by wire scanner at Sector3

M. Yoshida(A, B, C, D wires mean the different wire scanner monitors (multiple wire scanner) situated in the different locations of Sector3)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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e+ beam status

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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e+ beam status (I)e+ beam status• e+ production system• e+ generation and capture system is situated in the middle of Sector1. The system comprises oftungsten target inside flux concentrator (FC), bridge coil, DC solenoid, 10 large aperture S-band
accelerating structures. The tungsten target has a small hole with diameter of 2 mm. e- beam for
HER/light source injection traverses inside the hole. [P. 23, P. 24]• For e+ beam generation mode, primary electron beam with bunch charge of around10 nC, energy ofaround 3 GeV is impinging on the tungsten target with diameter of 4 mm.

• FC• FC made by oxygen free cupper was damaged by large discharge in Phase2. After this discharge, it isdifficult to apply the high voltage because of shortening of slit gap distance. [P. 25]• To improve FC head performance, Cu-alloy (NC50: Cu-Si-Ni) was adopted as FC head material. In
addition, FC design was also optimized. A new FC (current version) was manufactured, tested andfinally installed into beam line in summer shutdown FY2020. Since run2020c, the new FC has beensuccessfully in operation without any significant problem. [P. 26]• Sometimes FC operation was interrupted for a short time since the thyratron for FC has some noiseproblem. Some countermeasure was already applied (modification of cabling inside thyratron,
adjustment of reservoir voltage).
Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

21

e+ beam status (II)e+ beam status• e+ beam quality• Nominal e+ bunch charge has been improved from 1 nC to 2.5 nC at BT since the new FC has
worked in stable trough run 2020c to 2021b. [P. 27]• In summer shutdown FY2020, several BPMs and steering magnets in Sector1 after e+ target. They
can help to reduce the beam loss in Sector1 (after target) and Sector2. [P. 28]• e+ bunch charge after tungsten target already reaches 5 nC, and the best positron production
efficiency is 0.59 which already beyond the design value of 0.58. In the linac machine study day(July 6th, 2021), the e+ bunch charge of 3 nC was obtained at linac end and BT (final target 4 nC).
Remaining challenge is to reduce beam loss at the beam line between e+ capture section and DR
injection point (Sector1, 2, and LTR). Additional pulsed steering magnets in Sector2 could be
helpful for this issue. Pulsed steering in Sector1 is also helpful for this issue since the maximum
output current of these power supplies will be doubled. [P. 29, P.30]• Best emittance already satisfies the design value at BT1 with the bunch charge of 2.3 nC (final
target is 4 nC). For the emittance variation of e+ seems be stable in comparison with one of e- beam
because of DR. However, horizontal emittance (larger than 100 mm) is slightly worse than expectedvalue (65 mm). In the autumn run, low emittance optics of DR will be tested to examine the originof large horizontal emittance. [P. 31]
Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

22

e+ beam status

Positron source setup at Sector1
Positron target and capture section

DC solenoid
Large aperture S-band acc. Structures (x10)

W target + flux concentrator (FC)KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

Y. Enomoto et al.

23

e+ beam status

Positron Capture Section: Flux concentrator, bridge coil, solenoid
Large Aperture S-band acc. structure (LAS)
Bridge Coil (BC)Solenoid

Tungsten target

3.5 GeV e- beam

Flux Concentrator (FC)Cu-alloy (NC50: Cu-Si-Ni)
IFC= 12 kA
Masanori Satoh (KEK)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

Y. Enomoto et al.

24After large discharge…
After large discharge

Slit gap got narrow.
Not possible toapply high voltage
unless the gap will
be expanded.
Y. Enomoto
SuperKEKB review, 2019KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

25

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

26

e+ bunch charge history (2020a to 2021b)

e+ beam status(after e+ target)(before DR)(Linac end(BT)

2020a,b27

2020c

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

2021a,b27

e+ beam status

Steering magnet and BPM in solenoid section• There is no BPM and steering magnet between e+ target and 16_5 unit.
• DC steering (x4) and BPM (x4) will be installed in this summer shutdown.
• It could be help to cure e+ beam loss and e- beam emittance growth.

SY, BPMSX, BPMSX, BPM28
KEKBNoAccelerator
Sept.magnet
1-2, 6, 2021
BPMReview
andCommittee,
steering

Target: e+ W target
FC_15: flux concentrator
SC: screen monitor
AC: accelerating structure
SP: BPM
SL: solenoid
BM: bend
PX: horizontal pulsed steering
PY: vertical pulsed steering

28

emittancee(2.3 nC)～99.7/3.2 mm (BT)nx,nxyPositron yielde+ beam status• 5 nC at BPM<SP_16_5> (1st BPM after e+ target)• ～ 3 nC LTR (Linac To damping Ring) and downstream• For obtaining 4 nC at BT:
29

Goal: enx,nxy (4 nC)～100/15 (H/V) mｍ)

Y. Enomoto et al.

• Some more steering/Q magnets will be installed after target in 2021 (this summer).
• Increase gradient: 7.3 MV/m to 14.0 MV/m (design) for two structures (AC_15_1[2]situated at downstream e+ target)• Increase FC field and DC solenoid field. (power supply should be improved)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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Recent e+ yield history (run 2020a ～ 2021b)
design2020ab (operation)

2020ab(study)

2020c (operation)

2021a (operation)

2021b (study)

2020/7/1

2020/7/2

2020/10/12

2021/2/12

2021/7/6

Energy (e-)*

3.46 GeV

3.01 GeV

3.01 GeV

2.87 GeV

2.89 GeV

2.92 GeV

Bunch charge (e-)

10 nC

8.2 nC

8.3 nC

8.1 nC

8 nC

9.0 nCe+/e- @ SP_16_5

0.58

0.23

0.38

0.51

0.55

0.59

e+ @ SP_16_5

5.8 nC

1.9 nC

3.2 nC

4.1 nC

4.4 nC

5.3 nCe+ @ SP_28_4-

1.6 nC

2.4 nC

2.5 nC

3.2 nC

3.5 nCe+ @ SP_DC_4-

1.3 nC

1.9 nC

2.1 nC

2.5 nC

3.0 nCe+ @ SP_58_4

4 nC

1.3 nC

1.9 nC

2.1 nC

2.5 nC

3.0 nCe+ @ QMF8P_K**

4 nC

2.77 nC

2.95 nC

15_T : before e+ target
16_5 : after e+ target
28_4 : before DR
DC_4 : after DR
58_4 : Linac end

e+ beam status*LIiOP:AC_13_4:GAINSUM:KBP**BTpBPM:QMF8P_K_1:NC_1Hz × CGpBPM:QMF8P_K:FQ (0.475575)

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

Y. Enomoto, LCG (2021/7/6)30

e+ emittance history in run 2021a, b at BT1

e+ beam status• DR is effective for obtaining the stable low emittance positron beam.
• Machine study of low emittance DR optics is planned in this autumn.

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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Other subsystems

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

32

Subsystem

RF phase feedback

RF phase feedback can quicky
recover the beam operation mode
from maintenance mode.

Variation of rf phase and cooling water temperature(accelerating structure)

T. Miura

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

RF phase feedback:already deployed to many locations

33

Subsystem

Pulsed magnet

Pulsed magnet
BPM

Mounted on movable girder(remote controllable, 10 mm step)High stability of PS output

Schematic diagram ofcontrol system

DesignMeasured

Quad

0.1%

< ~0.006%

Steering

0.01%< ~0.003%

Future plan••
Y. Enomoto

Fast steering magnet is under development (kick only the 1st bunch or
only the 2nd bunch for reducing the orbit difference between 1st and 2nd
bunch).
This work is in progress as collaboration between PF and injector linac.

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

34

Pulsed steering magnet PS upgrade～ run 2021b

New (FY’21 summer)

Voltage

±50 V

±100V

Current

±10 A

±20 A

Voltage drop in PS

20 V*

1 V**

Output voltage

±20 V

±90 V

Inductance

3 mH

12 mH (7.5 mH for PX_A4_4)

Amp

PA12

PA04

# of production

35 (70 ch)

19 (38 ch) + 2ch

Installation location

SectorA
PX/PY_AT_22, PX/PY_A1_M
PX/PY_A2_1,
Sector1, 2
PX/PY_16_5, PX/PY_17_2
PX/PY_18_2, PX/PY_21_2
PX/PY_22_4,
SectorD, 1-5
PX/PY_DC_2 ～ PX/PY_58_4 (26 ch)

SectorA
PX/PY_A4_4
PX/PY_C7_4,
SectorJ-ARC
PX/PY_R0_01, PX/PY_R0_02,
PX/PY_R0_61, PX/PY_R0_63
Sector1, 2
PY_12_2, PX_13_2, PX/PY_13_5,
PX/PY_13_52,
PX/PY_17_4, PX/PY_18_4,
PX/PY_21_4, PX/PY_24_4
PX_23_4, PY_24_1, PX_26_1,
PY_26_4, PX_27_2, PY_28_2
Total: 32 ch

Black：in operation
Red：new
Blue：replacement

Total: 42 ch

Y. Enomoto

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

Subsystem(5A x4)35

Subsystem

Data archiving
・Archiver appliance
Linac archiver: ~ 110,000 data
In addition CSS archiver,2019/11～ Archiver Appliance in operation• Data retrieving speed performance x800
• Easy management• Load balance with clustering technology
・Synchronized measurement (BPM, RF, pulsed magnet)

Data retrieving speed performance between
CSS archiver and archiver applianceAll data are stored（ASCII → gzip）• Postmortem analysis of event
related to MR abort
Abnormalorbit• Abnormal beam orbit• Abnormal rf phase/amplitude• Abnormal pulsed magnet
current
Beam orbit display• Binarization of data
(HER/LER Abort event)with HDF5 format in progress
F. Miyahara
KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

I. Satake
Issue
Archiving data:・mutual easy access and usage oflinac/ring data
Synchronization of linac and ring data:
・Development of easy analysis tool・Automation of data processing
36Upgrade work
during FY2021 summer shutdown

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

37

Upgrade work during summer shutdown FY2021 (1)Upgrade• RF gun/laser system• 1st line laser: recovery of laser power (replacement of 2nd amplification)• 2nd line laser: increase laser power, DOE installation• Photocathode and laser window replacement• Backup rf gun line (AS line): New cavity will be tested.

• RF work• Sub-booster klystron• Sub booster of Sector2 was replaced by 600 W amplifier.

• Firmware of all control units will be replaced for noise proof• Accelerating structure• AC_44 waveguide replacement• AC_55, 61 waveguide examination
38

KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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Upgrade work during summer shutdown FY2021 (2)Upgrade• Magnet• Pulsed magnet• New pulsed steering: PX[Y]_A4_4, PX[Y]_C7_4, PX_23_4, PY_24_1, PX_26_1• Pulsed steering power supply upgrade: x21 in Sector J-ARC, Sector1, and Sector2• Quad: high precision DCCT• DC magnet• New Quad will be installed (QF_61_3) for the dispersion correction of ECS.
• New steering magnet PS (in-house development) in Sector1-2, and Sector6• Control system• New server computers will be in operation.
• Control network update (core switch, part of edge switches)• 1 Gbps to 10 Gbps connection• Event generator operation sequence length is changed from 16/18 to 8/9(improve the proofness of TEPCO 50 Hz interval variation)
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KEKB Accelerator Review Committee, Sept. 1-2, 6, 2021

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Summary

Simultaneous top up injection operation of 4 storage rings (SuperKEKB HER/LER, PF, PF-AR) has beensuccessfully conducted.
Synchronized pulse-to-pulse monitoring system (BPM, rf phase/amplitude, pulsed magnet power supply)
and analysis tool work fine, and is helpful for the postmortem analysis of beam abort event.
e- beam• Laser system works fine without any significant trouble.
• Bunch charge of 2 nC was ready at the beginning of run 2021a. However, bunch charge wasdecreased to around 1.5 nC after discharge in the end of March since the cavity power and rf pulse
width were decreased to avoid the discharge.
• 2nd line laser power will be upgraded, and DOE will be installed for 2nd line in this summer.
• 2 bunch injection is key challenge in the autumn run. Careful rf conditioning will be carried out for
expanding the rf pulse width. It could help to improve the 2nd bunch emittance.
e+ beam• The new FC is working fine .
• Reached bunch charge of 3 nC at BT end.

• Issues• Emittance reproducibility of e- beam is not stable. Additional orbit feedback by using new pulsed
steering magnets could be helpful.
• Emittance growth at BT#2 is also issue.
• Deteriorated subsystem replacement is also issues for the future operation. (damaged acc. Structures,
KEKB Accelerator andReviewso
Committee,
Masanori
Satoh (KEK)oldmagnetpower supply and controller,on) Sept. 1-2, 6, 2021

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