Linac status
Masanori Satoh (Acc. Lab. Div. V, KEK)
on behalf of Injector Linac Group and Linac Commissioning Group

44th B2GM, Feb. 13-17, 2023

1

Contents• Injector outline, e-/e+ status and issue• Upgrade work during LS1• ARC recommendations• Summary

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

2

Outline

Injector Linac Layout

・Two electron sources:
RF gun: HER injection
Thermionic DC gun: LER, PF, PF-AR
・Sector 3-5:
All magnets are pulsed magnets.
1.1 GeV e+
Damping Ring
Continuous orbit feedback
・DC magnet settings are same for different
beam mode

60 klystron units
240 accelerating structures (S-band 2-m-long)

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

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 GeV
C

1

2

3

4

5

3
Beam
beam
mode
along
the
beam
line
after
J-ARC
Linac Status, Masanori Satoh(KEK)energy variation for each44th B2GM, Feb. 13-17, 2023

3

Simultaneous top up injection to 4 rings + DR (May 2018-)
Outline- stored current and linac beam orbit Stored current (1 day)

Linac/BT beam orbit
HER

LER

x
(mm)
y
(mm)

I (nC)

PF-AR

Linac Status, Masanori Satoh
(KEK)
since
May 2018

44th B2GM, Feb. 13-17, 2023

PF4

e- beam status and issue

44th B2GM, Feb. 13-17, 2023

5

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. Yoshidaal. Satoh (KEK)
Linac Status,etMasanori

44th B2GM, Feb. 13-17, 2023

6

e- beam status

Hybrid laser system for rf e- gun•

Yb doped fiber and Nd:YAG DPSS module Amplifier••••

Output Power in 1st line:ω (1064 nm): 32 mJ
2ω ( 532 nm): 12 mJ
4ω ( 266 nm): 1.3 mJ

1st laser
2nd laser

Laser roomon theground virtualKLY Gallery

cathodediagnosticsLaser line to RFGun
TunnelRF-GunR. Zhang,
X. Zhou
et al.Masanori Satoh (KEK)
Linac Status,
Optics layout in thetunnel44th B2GM,
Feb. 13-17, 2023
7

Laser transport line

7

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) were installedat 1st /2nd (in summer ‘20/‘21) line laser: Laser beamhomogenizer for low emittance beam with thehigh intensity bunch charge.

DOE is installed in vacuum
chamber filled with Argon gas.

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

world first DOE application in UV laser

R. Zhang 8

e- beam statuse- bunch charge history (2020a to 2022c)(from rf gun)(BT)

2020a,b2020c

2021a,b2021c

2022a,b

2022c
(LS1)

High bunchcharge study
discharge

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

Bunch charge
feedback9

Issue of rf gun laser window degradatione- beam issue• Long term operation makes rf gun laser windows dirty for both of 1st and 2nd line.
• It decrease the transmittance of laser power through window and bunch charge intensity.
• After replacement of the laser window, the bunch charge intensity is recovered.
• Vacuum ion pump was installed between the laser window and rf gun cavity with theextension vacuum duct for the 1st line laser in this summer maintenance ‘22.

Bunch charge (nC)e- intensity by 1st-line laser

new window
degraded window

1st-line laser incident position [mm]e- intensity by 2nd-line laser

new window
degraded window

2nd-line laser incident position [mm]M. Yoshida
Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

10

Improvement of laser window degradation with ion pump

e- beam issue• Long term operation for keeping e- bunch charge is very important issue.
• Continuous beam test at e- beam repetition of 22 Hz has been conducted more than 5 days.
• Installed ion pump could help to mitigate the laser window degradation from the experimental
results.
• This test will be continued until the end of this run. Further improvement is also being
considered.
Degradation test of 1st/2nd line laser window

Quantum efficiency

1st laser line (adding ion pump)
2nd laser line

5 daysLinac Status, Masanori Satoh (KEK)

Elapsed time
HH:MM:SS
44th B2GM,
Feb. 13-17, 2023

M. Yoshida11

e- beam summary and issue

e- beam issue• Thermionic DC e- gun has worked fine.

• Photocathode rf e- gun• Laser system and DOE element has worked fine without any significant trouble.

• Increase of bunch charge• High bunch charge e- was demonstrated. Achieved 5 nC from e- gun and 4 nC at the linac end.
• However, the beam loss at J-ARC and e+ target location should be minimized. Beam orbit stability should bealso improved.
• Further beam study will be continued during LS1.

• Issue• Gradual decrease of bunch charge due to laser window deterioration. It could be solved by adding theextension vacuum chamber and ion pump.
• Emittance at the linac end and BT1 (before Arc1) is almost satisfied the final goal while bunch charge (2 nC)
is less than final goal (4 nC).
• However, emittance at BT2 is increased due to ISR, CSR, and some other reasons.
• Increase of 2nd bunch injection efficiency and improvement of its stability are important issues.
e- emittance

Measured enx,nxy (2 nC) : 20/20 mm (at BT1)
Goal: enx,nxy (4 nC) : 40/20 (H/V) mｍ

44th B2GM, Feb. 13-17, 2023

12

e+ beam status and issue

44th B2GM, Feb. 13-17, 2023

13

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)44th B2GM, Feb. 13-17, 2023

Y. Enomoto et al.

14

e+ bunch charge history (2020a to 2022c)
2021a,b2020c2020a,be+ beam status(after e+ target)(before DR) ・Solenoid current (SL_16_)optimization(Linac end) ・beam tuning (primary e- bunch charge ↑)
(BT)
2022c

2021c

2022a,b(LS1)・beam tuning

・Steering, BPM
in Unit 1-5, 1-6
・beam tuning
・New FC
・Solenoid
current↑

・decrease bunch charge(MR request)

Linac Status, Masanori
Satoh (KEK)
15

44th B2GM, Feb. 13-17, 2023

15

e+ beam summary and issue

e+ beam issue• e+ bunch charge is almost achieved (final target: 4 nC)••••

6 nC at BPM “SP_16_5” (1st BPM after e+ target)
4 nC at LTR (Linac To damping Ring)
3.5 nC at linac end and BTe+ production efficiency with the current FC is reached the simulation result (60%).

• Further improvement of positron bunch charge• Increase acc. gradient of first two structures (AC_15_1[2]) at e+ capture section• Increase primary e- bunch charge, beam tuning, FC power supply upgrade, and so on• Issue• Emittance at linac end and BT1 (before Arc1) is almost satisfied the final goal.
• However, emittance at BT2 is increased due to ISR, CSR, and some other reasons.
• Horizontal emittance after DR is larger than design value. Low emittance DR optics will be tested after LS1.

e+ emittance

Measured enx,nxy (3 nC) : 103.5/4.7 mm (at BT1)
Goal: enx,nxy (4 nC) : 100/15 (H/V) mｍ

Y. Enomoto
44th B2GM, Feb. 13-17, 2023

16

Upgrade work during LS1

44th B2GM, Feb. 13-17, 2023

17

Upgrade during LS1

Upgrade work during LS1• Pulsed Quads• at J-ARC matching section• at Sector1, 2 (e-/e+ compatible optics region)• New accelerating structure

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

18

Pulsed Quads at J-ARC for optics matchingUpgrade during LS1

e- beam• At the entrance and exit of 180 deg. J-ARC region,a good optics matching is very important to mitigate beamloss and emittance growth.
• Simultaneous matching for both of HER/LER injection
beam requires the pulsed quads.

matching
section• From the simulation result, 4 pulsed quads at both ofentrance and exit of J-ARC are sufficient.

matching
sectionY. Okayasu

e- beam

Bmag yCurrent optics at J-ARC

New optics at J-ARC
with pulsed quads

Bmag xLinac Status, Masanori
Satoh (KEK)Matching
simulation

44th B2GM, Feb. 13-17, 2023

e- beamY. Seimiya 19

Pulsed Quads at Sector1, 2 for e- low beta optics

Upgrade during LS1• Current optics at Sector1, 2• Large emittance e+ beam is accelerated from 0.1 GeV to 1.1 GeV for DR injection.
• Quad settings is optimized for e+ beam.
• For e- beam (3 ～ 4 GeV), focusing force is weak in comparison with optimum parameter. It could cause theemittance growth.

Four DC quads will be replaced by pulsed one.

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

20

Pulsed Quads at Sector1, 2 for e- low beta optics (cont’d)Upgrade during LS1• After only these four pulsed quads are optimized for the e- beam, the betatronfunction can be decreased.
• Simulation result shows that it can help to decrease the emittance less than half.
Δγε𝑥 ~ 100 um, 𝛽𝑥 = 45.2 m••Δγε𝑥 ~ 40 um, 𝛽𝑥 = 16.3 m

End of LAS cavity
Start of S-band
cavityBunch tail is kicked back byquad, and temporally
emittance is reduced.

e+ target

Sector2 end

Before optimization
Linac Status, Masanori Satoh (KEK)

achieved smaller
betatron function

e+ target

Sector2 end

44th B2GM, Feb. 13-17, 2023 After optimization

Y. Seimiya 21

New accelerating structure

Upgrade during LS1• Mitigation of accelerating structure failures• Originally designed for 8 MeV/m (PF injector), but used at 20 MeV/m (KEKB upgrade)• Degradation that lead to high field emission rate and discharges• Water leaks, field emission , discharge in waveguide, and so on (29 of 60 units have some problems)• Not only future Y(6S) but even Y(4S) could be suffered

Damaged iris

• 5-year upgrade plan to fabricate and install new accelerator structures (FY2018 –FY2022)• 4 units (16 acc. structures) will be replaced by new one. (Unit44 was replaced in this summer)• New acc. structure: acc. gain ↑7%, surface field ↓20% (reduce breakdown)• New pulse compressor (SCPC) was also developed and installed in Unit44.

Colling water leakage

New S-band
2-m-long TW acc. structure
Linac Status, Masanori
Satoh (KEK)

New pulse compressor
44th B2GM,
Feb. 13-17,Pulse
2023
Spherical-Cavity
Compressor (SCPC)

H. Ego22

ARC Recommendations:••

R7.1: Perform systematic measurements of the orbit jitter of the two electron bunches and correlations with possible
sources. Advance the synchronous data acquisition between Linac and BT.
R7.2: More generally, perform a feasibility study for the implementation of synchronous beam data acquisition, which
will be extremely useful for studying drift and instability.
Improve the postmortem analysis tools using the synchronous beam, rf monitor, pulsed magnet data•

R7.3: Implementation of an orbit feedback if the use of pulsed magnets allows for this.
Orbit FB with pulsed magnet is already in operation (Sector3-Sector5).

•

R7.4: Continue with the upgrade plan as presented in the summary slide.

•R7.5: Concerning the emittance growth of the second electron bunch, study the effect of long range-wakes in the linac.
Fast kicker for 2nd bunch orbit correction could mitigate the 2nd bunch emittance growth.

•

R7.6: Identify the causes limiting the charge of the electron bunch along the injector.
Simulation work and beam study will be conducted during LS1.

•

R7.7: Discover the loss locations and causes for the positron transport in the linac.
Simulation work is now in progress. Beam matching after e+ target will be tested soon to reduce the beam loss.

Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

23

Summary•

Simultaneous top up injection operation of 4 storage rings (SuperKEKB HER/LER, PF, PF-AR) + DR has beensuccessfully conducted.

•

e- beam• Laser system has worked fine without any significant trouble.
• DOE was installed also at 2nd laser line in the last summer maintenance, and it has worked fine.
• In the run 2022a/b, bunch charge of 2 nC can be kept with bunch charge feedback.
• 5 nC from gun was demonstrated. Further beam study will be continued during LS1.

•e+ beam• The new FC is working fine.
• Reached bunch charge of 3.5 nC at BT end (final design 4 nC).

•

Upgrade work during LS1• Pulsed Quads (x8) at J-ARC for the simultaneous dedicated matching of HER/LER injection beam
• Pulsed Quads (x4) at Sector1, 2 for low beta optics of HER injection beam
• New accelerating structure• Replacement of air conditioners at SectorA, B (in the accelerator tunnel)• Fast kicker for 2nd bunch orbit correction•

Issues• Emittance growth at end of BT for both of e- and e+ beam
• Low e- injection efficiency of 2nd bunch (fast kicker could help)• Increase the e- bunch charge while keeping small emittance
Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

24

Backup

Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

25

Parameters
Stage

KEKB
(achievement)

SuperKEKB
Phase-I(achievement)

OutlinePhase-II(achievement)

Phase-III
Summer’19(achievement)

Phase-III
Summer’20(achievement)

Phase-III
Summer’21(achievement)

Phase-III
Summer’22(achievement)

Phase-III(final)

Beam

e+

e–

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

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

1.460

1.145

3.6

2.6

Life time (min.)

150

200

100

100

50

100

20
(typ.)

70(typ.)

12

21

9

22

6.7

26

6

6

primary e10
Bunch charge(nC)

primary e10

primary e- 8
1

1.6

3.6

1.35

3.5

1.6

3

2.5

1

1

→ 0.4

1400

31
0

1000

13
0

200/5
(Hor./Ver.)

200/40

120/6

54/67

100/2

41/45

100/6

Energy spread

0.13%

0.13%

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

Bunch/Pulse

2

2

2

2

2

2

1

1

1

1

Norm.
Emittance

primary
e- 10

2

4

2.1
→ 3.5

→4

100/80

120/5
(BT1)

20/20
100/15
(BT1)

n/a

n/a

-

-

0.16%

0.07%

2

1

2

1

2

2

40/20

(gbe) (mmrad)

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+PFAR < 25 Hz)

50 Hz

50 Hz

50 Hz

4+1 rings (LER, HER, DR, PF, PF-AR)
44th B2GM, Feb. 13-17, 2023

26

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

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

27

Layout of LINAC, BT to MR
e- beam directly injects into HER:
The injeciton BG is directly affected by
the condition of RF-gun, LINAC, and BT.

e+ beam injects into LER via DR:
The injection BG is not affected verymuch by the condition upstream the DR.

Injection Points
LINAC
1.1GeV Damping Ring (DR)for positron

Beam Transport line (BT)Arc4primary e- for e+: Therminic Gun

Jarce- : RF Gun
SectorB SectorA
SectorC

Sector1

LTR

BCS
Sector2

ECS

BT1

Sector3

Sector4

BT2

ECS
for e+

Arc2-3

Sector5e+ target

Green: Emittance measured with wire scanners(WSs)
BCS: Bunch Compression System
ECS: Energy Compression System
44th B2GM, Feb. 13-17, 2023

Arc0

BT1

Arc1

N. Iida28

Injection efficiency of 2nd bunch

e- beam issue• HER injection efficiency of e- 2nd bunch is lower than that of 1st bunch and varies gradually.
• In some cases, there is not clear correlation between injection efficiency and orbit of 2nd bunch.
• Low injection efficiency could be also caused by the emittance deterioration.
• Fast kicker for 2nd bunch orbit correction could be effective. Two fast kickers will be installed at the linac end andthe beginning of BT in summer ’23.

Vertical beam position at BT• Prototype kicker was installed at the entrance of J-ARC in this summer ’22. Beam test will be conducted soon.

Ver. position of 2nd bunch at the BT end

Injection efficiency
differenceN.
Iida
Linac Status, Masanori Satoh (KEK)Ver. position of 1st bunch at the BT end

Difference between 2nd and 1st bunch
Injection efficiency(Lower 2nd bunch efficiency means negative value)
44th B2GM, Feb. 13-17, 2023

29

LinacSatoh
Status,Masanori Satoh (KEK)
Masanori(KEK)

44th B2GM, Feb. 13-17, 2023

T. Natsui, eeFACT202230

入射効率低下

水平軌道差と入射効率

The different between 1st and#2 bunches have no dependent
on the injection efficiencies.
It is considered that theemittance of 2nd bunch had
been increased.

垂直軌道差と入射効率
入射効率#1

入射効率#2垂直軌道差(#2-#1)

水平軌道差(#2-#1)

BT終端での水平軌道 #2

BT終端での垂直軌道 #2
BT終端での垂直軌道 #2

BT終端での水平軌道 #1

入射効率 #2-#1

BT終端での垂直軌道 #1
BT終端での垂直軌道 #1
入射効率 #2-#1

特にHERでは、この期間は２バンチ目の入射効率は垂直軌道変化に依存している。
この時、水平軌道はほとんど変化がない。44th （１バンチ目のみ、軌道FBが働いているため、２バンチ目だけがDriftしている）
B2GM, Feb. 13-17, 2023
２バンチ目の垂直軌道補正のために、Fast
kickerを設置する。

High bunch charge e- beam test
5 nC beam from rf e- gun, 4 nC at the linac end

Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

e+ beam

44th B2GM, Feb. 13-17, 2023

33

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)

44th B2GM, Feb. 13-17, 2023

Y. Enomoto et al.

34

44th B2GM, Feb. 13-17, 2023

35

Comparison FC baseMaterial

Shape

RemarkFor e-For e+

Base 5

OFC
+
SS400

Old design

12 kA in beam line
large slit gap△○

Base 7NC50+
permendur

Old design

4.5 months test

○

○+ *

Base 8NC50+permendur

New design(optimized)
in operation

Cooling water leakage wasfound.
(already fixed and tested during
4 days)◎○+ *All FC bases achieve 12 kA in test stand. (*) return yoke (permendur) makes higher magnetic field.
Base 8

Y. Enomoto

・Optimized yoke shape・Reinforced insulation (FC head support)

44th B2GM, Feb. 13-17, 2023

Base 7 and older

36

Recent progress

44th B2GM, Feb. 13-17, 2023

37

SR monitor at J-ARC

Recent progress• SR monitors (SRM) were installed at J-ARC and ECS in the beginning stage of KEKB operation. After then, they
became obsolete. SRM at ECS was removed after reconfiguration of ECS magnet.
• SRM at J-ARC is recently used as a non-destructive profile monitor with the reconstructed optical system.
• Similar system at BT has been also available since this November.

R. Zhang et al.
J-ARC layout

SR extraction
port
LinacSatoh
Status,Masanori Satoh (KEK)
Masanori(KEK)

Control GUI

SR monitor (J-ARC)
44th B2GM, Feb. 13-17, 2023

SR monitor (BT)38

SR monitor at J-ARC (cont’d)Recent progress• Centroid position of the beam profile images are synchronously measured by SR monitor and screen monitor(SCM) with the different beam energy. Each of them and BPM show a good agreement.
• Measured profile images are slightly different between SCM and SRM.
• SRM could be a strong help for beam feedback as a nondestructive monitor.
Beam profile Imageby changing klystron phase

SCM

SRM

Projection plot

SCM

SRM

Centroid position (SRM, SCM)
vs beam energy

J-ARC layout

Linac Status, Masanori Satoh (KEK)

Right/Left definition is opposite
44th B2GM, Feb. 13-17,
2023SCM and SRM
btwn

F. Miyahara, Y. Seimiya 39

Lowemittance
ewith
bump
orbit
• Measured emittance and beam size at Sector5 and BT by changing vertical orbit (Sector3-5)

Recent progress• Finding the beam orbit minimizing emittance (mitigate emittance growth due to transverse wake field effect)• Correlation btwn the emittance and beam size is confirmed with the measured data at Sector5 and BT.
at BT

Ver. bump height
Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

Ver. norm. emittance
Bmag x ver. norm. emittance

Bmag x ver. norm. emittanceVer. beam size sy (mm)Ver. norm. emittanceat Sector5

Y. Seimiya

Ver. beam size sy (mm)Different ver. bump height @ Sector3-5• It could find and keep the orbit minimizing emittance with SRM at BT even during beam injection.

Ver. bump height40

Automatic beam tuning

Recent progress• Automatic beam tuning approach with machine learning is recent trend in accelerator operation.
• Bayesian Optimization approach is now under test by using the beam of injector Linac.
• Implementation using GPyOpt Python library (T. Natsui) / In-house developed implementation (G. Mitsuka)

Preliminary test result with GPyOpt• Setup:T. Natsui• Explanatory variable: excitation current of 4 pulsed steering magnets at J-ARC exit
• Objective function: bunch charge calculated from 4 BPMs at around the e+ target• Bunch charge before LTR was increased from 3.5 nC to 3.7 nC after optimization.
• Best parameter was found within ～ 5 min. (depending on beam rep. , # of number of averaging points, and so on)• Optimization result seems to be same level by the operator.

• In the future, try to apply it to more complicated tuning like 2nd bunch beam tuning, dispersion correction,
injection tuning (after LS1).
Steering
current(normalized)

4 pulsed steeringx(mm)

I (nC)

e+ target

Before optimization

After
optimization
44th
B2GM,
Feb. 13-17, 2023

Objective valuey(mm)# of trial

BPM (with 8 stripline electrodes) at J-ARC

Recent progress• Special BPM (S8) at J-ARC can obtain the quadrupole moment (Jq) of beam. It help to measure the energy spread.
• Results measured with S8 (nondestructive) and SCM (destructive) are comparable.

BPM (w/ 8 electrodes)
S8_R0_31

y position (S8) (arb. units)

Jq (S8)x beam size (SCM) (pixel)

x position (S8) (arb. units)

SCM
SC_R0_31

Klystron phase SectorB (deg.)

J-ARC
layoutLinac Status, Masanori
Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

Changing klystron phasey position (SCM) (mm)x position (SCM) (mm)• Both of S8 and SRM can work complementary as nondestructive monitor for beam tuning and feedback.

Klystron phase SectorB (deg.)

F. Miyahara

42

Postmortem analysis
of beam abort event

Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

43

Postmortem analysis of beam abort event

Recent progress

Abort event

Beam abort coincidence w/ injection:
Linac/BT orbit, RF monitor, pulsed magnet
PS are abnormal or normal?
It can be easily checked via web pageautomatically created.
Linac Status, Masanori Satoh (KEK)

44th B2GM, Feb. 13-17, 2023

44