Injection
T. Yoshimoto
on behalf of
LINAC beam analysis group, Beam Injection Task Force (BITF), and Injection Commissioning Group (ICG)

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

Content
•
•
•
•

•

•

Injector complex overview
Injection status
BT beam emittance issues
4-GeV positron studies in BT• 1.1-GeV positron beam emittances at RTL after damping ring
• Beam bump studies on unidentified CSR• XY coupling studies• Raster scan to observe “magnetic lens” distortion• Summary of emittance blowup• LER dynamic aperture (βy* = 3~1 mm)
7-GeV electron beam status in BT• Electron beam emittance status• Local vertical bump study in BTe Arc1-3 & dispersion measurement• HER dynamic aperture (βy* = 3~1 mm)• On-momentum dynamic aperture degradation due to QCS cancel-coil errors• TbT-BPM measurements in HER (βy * = 1 mm)• Synchrotron injection
Summary
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

2Injector Complex Overview

7-GeV e- & 4-GeV e+ Beam Transports (BT)7-GeV HER
injection point

LINAC

4-GeV LER
injection point

1.1-GeV DR (e+)
1.5-GeV J-ARC

DR:
LTR:
RTL:
ECS/BCS:BT:
LER/HER:••

Thermal Gun(10 nC e-) for e+
RF Gun(2~4 nC e-)

PositronTargetRTL
BCS (e+)LTR
ECS (e+)

BTe2
BTp
2

ECS (e+)BTe1/positron Damping Ring
Linac-To-DR Beam Transport
DR-To-Linac Beam Transport
Energy/Bunch Compression System
Beam Transport line
Low/High Energy Ring for e+/e-

Arc4

Arc3
Arc2

BT
p1

Arc1

Injector beam parameters (design)*:

How to achieve these parameters toward higher
luminosity?
Emittance blowups in BTe/p are currently one of thebottlenecks.
* H. Akai, et al., https://arxiv.org/pdf/1809.01958.pdf

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

3

Storedcurrent

Short-term Injection Status (βy* = 1 mm)
HER
LER HER
Effective Inj. Efficiency

HER

Raw inj. efficiency

Measures:1) two-bunch injection, 2) higher bunch charge,3) higher rep. rate, 4) low-emittance injected beams, …

HER QCS background

Short lifetime

LER

Raw injection efficiency : 20~40%
Effective injection efficiency : ~20%.
Large injection background•••Raw inj. efficiency
Effective inj. efficiency

LER
•
•

LER QCS background•
HER: QCS (Diamond) BW135
LER: QCS (Diamond) FW135

Raw injection efficiency : ~ 90%
Effective injection efficiency : 10~90%(shorter lifetime at high currents)
Large injection background

Measures:1) two-bunch injection, 2) higher bunch charge, 3)higher rep. rate, 4) large dynamic aperture, …

Most sensitive to the Background (BG) on Belle2.

Injected beam quality and stability are the key toward high current operation => 1) higher injection efficiency, 2) lower
background, 3) fewer injection related aborts => relaxed collimator setting => lower impedance, …
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

4Injection Stability (Feb. 1~ Mar. 21, 2024)
LER

HER
•
•

•

After βy* = 1 mm, poor raw beam injection efficiency:
60% → 20%
Low stability of raw beam injection efficiency

Low stability of raw beam injection efficiency:
60 ~ 90%.

R56 in J-ARC: 0.3 → 0
Injector tuning

βy* :81 mm

8 mm 3 mm

βy* :48.6 mm
1 mm

8 mm

3 mm

1 mm

Raw inj. efficiency
Raw inj. efficiency

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

5

BT Beam Emittance Issues
HER

BTp2
BTp1

Previous MAC in 2022. 12•

Primary sources of horizontal emittance blowup in BTe1):•

Vertical emittance blowup remains unaddressed. (3D-CSR?)

1) ISR (incoherent synchrotron radiation): +~30 µm
2) CSR (coherent synchrotron radiation): +~60 µm (2 nC)

1) https://www-kekb.kek.jp/MAC/2022/Report/Iida.pdf

LER As of 2022, we did not know emittance blowup sources in LER-BT.
•
•

We sh
Nominal particle tracking simulations (SAD, ELEGANT) after DR show negligible ISR and CSR effects.
ould cMeasured results showed large bunch-charge dependent emittance growths.
heck
Does a longitudinal spiky bunchit!
profile cause unidentified CSR
effect?
6
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

Positron Beam Studies

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

71.1-GeV Positron Beam Emittances in RTL After Damping Ring
Beam size measurement with a DR-SR monitor

1.1-GeV DR (e+)

measured by H. Ikeda

RTL
BCS (e+)LTR
ECS (e+)sx~0.4mm
sy~0.15mm<latexit sha1_base64="fAhEbYK1As+S1kUHl6F7tJBk0XQ=">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</latexit>x = 3.4 m

⌘x =

25 mm

x ⇠ 0.4 mm= 5.5 4<latexit sha1_base64="32yAm0Nr2zAJ5qCLEfvAnjtzGow=">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</latexit>

"x =

2
x

(⌘x

)2

<latexit sha1_base64="JJVdzBBiEGfoZfnjkSRGfQI2pwM=">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</latexit>= 47.0 nm

x<latexit sha1_base64="PptQ2ZJazH1gooZKYWRr24e9pAI=">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</latexit>"x = 101.2 µm

y = 5.7 m
y ⇠ 0.15 mm
2y"y == 3.95 nm
y"y = 8.50 µm

Design@ DR

SR monitor Q-scan with OTR@ DR
screen @ RTL

gex [µm]

65

101.2

70~76.0

gey [µm]

0.65

8.50

0.2~0.24• No large emittance blowup after DR• No large bunch charge dependence of beam emittances
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

8How to Confirm Unidentified CSR Effect in BT
What is the source of emittance growth?:
Unidentified CSR effect can be caused by a longitudinal spiky bunch profile.
Countermeasure setup:
Most beam ducts of bending magnets in Arc1 were offset to suppress unidentified CSR
Off-axis shielded CSR effect[1]effects.
[1] T. Mori, IPAC2023

See talk on “BT” for hardware in detail

BTp
2

BTp1
N. IidaSide effects:

Arc11) Large resistive wall (RW) impedance
RW impedance can increase beam emittances due to the finite conductivity of beam ducts.
2) Vertical dispersion caused by vertically offset bending magnets
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

9Countermeasures Against Side Effects
Off-axis RW impedance effect[1]:Optics with ver. dispersion suppression in Arc 1:
T. Ishibashi , T. Yoshimoto
N. IidaSimulation results:•

Simulation results:

Significant vertical emittance growth was caused by duct
displacement >= 14 mm in this simulation, whereas13 mm
displacement was acceptable.

Optic can be cured with vertical correctors
and quadrupoles

13 mm duct offset is not harmful and adapted.
[1] T. Yoshimoto, BITF, Aug 25, 2023, https://kds.kek.jp/event/47643/

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

10BTp-Arc1 Bump Height Dependence of Beam Emittances @ MSP15

ECS

BTp1 ver. bump height

MSP15 (OTR)
Ver. bump height:

14 mm
0 mm

Measurement: 20231228

Vertical emittanceVer. trajectory

Horizontal emittance

Scheme:1. Change BTp Arc1 bump height:0, 14 mm
2. Measure vertical emittance with MSP15-OTR

Beam

Measurement results:
1) ECS setting slightly affects hor. and ver. beam emittances.
2) BTp Arc1 vertical bump height does not change hor. and ver. emittances at MSP15 in BTp2.
=> No symptom of CSR wake and RW wake effects
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

11BTp-Arc2-3 Bump Height Dependence of Beam Emittances @ MSP15

Ver. trajectory

Normalized emittances

Mismatch factor: Bmag

Horizontal
emittance

Scheme:1. Change BTp Arc2-3 bump height: -10 ~ 3 mm
2. Measure vertical emittance with MSP15-OTR

MSP15 (OTR)
Ver. bump height:

0 mm-14 mmBeam

Verticalemittance

Design limit

Design limit

Measurement results:
Measurement: 20231223• No large bunch-charge dependence of beam emittance was observed.
=> No wake field effect including CSR effect. It is consistent with nominal simulation results.
• Ver. bump height dependence of beam emittance and Twiss params were observed.
=> There would be unidentified (high-order?) magnetic errors in BTp-Arc 2-3.

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

12Energy Spread Dependence of Beam Emittance
Energy spread @ MSP6

Hor. Emittance @ MSP15

ECS-ES: 35 kV

Ver. Emittance @ MSP15

Measurement:~202312240700 (3 nC), 202312242300~ (1, 2 nC)• LINAC RF phase for minimum energy spread generally does not give minimum beam emittancesin both hor. and ver. directions.
• In actual operation, the phase should be optimized to minimize
1) energy spread, 2) hor. emittance and 3) ver. emittance comprehensively.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

13Local Vertical Bump Study in BTp Arc2-3
Where are unexpected magnetic errors?

QBD2P: -14mm

Scheme:1. Change a local vertical bump position:
2. Observe X-Y coupling from BPM signals

ΔX
ΔY
QBD4P: -7mm
BT1

ΔX
ΔY
QCD2P: -14mm

BTp2

ΔX
ΔY

N. IidaQCD4P: -7mm
ΔX
ΔY
QCD6P: +12mm
ΔX
ΔY
QCD6P: -7mm
ΔX
ΔY

• Unexpected X-Y coupling was observed near Arc3 entrance.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

14History of BTp Arc 2-3• Arc3 bending magnet (BH3P type):• Saddle-type coil
• Non-conventional V-shaped yoke
• Asymmetric insertion of 6-mm iron plate on upper pole surface (BH2P, BH3P)
to increase dipole field• Permanent skew quads at the entrances of many Arc2-3 bending magnets
BH2P.7 in this• In the past, they were placed to reduce unexpected vertical dispersion
section.
• It works well to reduce vertical emittance blowup significantly,
although vertical residual emittance blowup remains (M. Kikuchi).

BH3P.1

BH3P type6-mm iron plate

Permanent skew
quad.

• Physical sources of the XY coupling have notbeen identified.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

15

Arc2-3 XY-Coupling Analysis• In simulations, some quadrupole rotation errors reproduce the XY coupling, although experts say such large
rotational errors are unlikely.
• Each error case has solutions for XY-decoupling with a new skew quad around the first bending magnet of Arc-3• Further study is ongoing.

Y. Seimiya
Simulations:(1) QCF1P: -1 deg.

Measurement:

v

v

(2)

QCD2P: +3 degv
こちらの⽅が測定パターンと近い

ΔX
ΔY
QCF1P: -1 deg
v = 0.0065& Skew Q SK1@BH3P.1

3/25/2024

QCD2P: +3 degv& Skew Q SK1@BH3P.1 = 0.0065

T. Yoshimoto | The 27th KEKB Accelerator Review

v

16Realistic SAD Simulations With Multipoles of Bending Magnets and Others

K. OideThis simulations reveal that 1) multipoles of bending magnets and 2) sextupole component
from the measured XY coupling can reproduce measured X/Y emittances in BT2.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

17Raster Scan to Observe “Magnetic Lens” Distortion
Basic idea:
In general, beam optics and light optics have a common theory=> Beam optics distortion is visually observable!

[1]

Pr
eli
mi
na

Scheme:1. Change X and Y corrector kicks in BT1 in a grid pattern.
2. Measure downstream BPM response.

X (mm)X (mm)

Results:••••

Y (mm)Y (mm)Y (mm)Y (mm)

BPM response:

X (mm)X (mm)

Slight XY coupling is observed in Arc-2
Strong XY correlation just after the first Arc-3 bending magnet
It is useful to get better linearity region in a magnetic field.
Further study is necessary.
[1] https://clickitupanotch.com/wp-content/uploads/2014/06/lens-distortion-graphic.jpg

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

18rySummary of Emittance Blowup

Plot: Y. Ohnishi•

The horizontal blowup here is suspected at anaccelerator structure in the BCS.

•

The vertical blowup here is being understood by
the BT study in 2023.

Arc2-3

DR

DR出射路
(RTL)

LINAC
Sector 3-5

3 nC

DR
(design)

RTL(MSs08)

Sector 3(WSs)

Sector 5(WSs)

BT1(MWP.1-4)

after Arc1
(MSP.8)

BT2(MSP.15)

gex [µm]

65

76.04

147.5

228±53156.5±35.9

155

175

gey [µm]0.65(k=1%)

0.24

1.5

2.2±0.3

11.3±2.6---

24

3 [nC] e+
BT1→BT2

Measured

Simulation(K. Oide)

gex [µm]

130→175±10

130→160

gey [µm]

5

5

→20±1
3/25/2024

→17

BT1

Arc1

The simulations have good agreement with themeasurements.
T. Yoshimoto | The 27th KEKB Accelerator Review

19

BT2

LER Dynamic Aperture (βy* = 3~1 mm)

Y. Ohnishi, N.Iida

1) Hor. aperture
gex=221.91µm

βy* LER

3 mm

1 mm CW off

1 mm CW 80%

Measured (Simulated)horizontal acceptance, 2Jx [µm]2.24 (4.88)

1.13 (3.77)

0.90 (3.37)

Maximum action of
injected beam (6.25εx_rms), 2Jx [µm]2) Ver. aperturepyyβy* LER

3 mm

1 mm CW off

1 mm CW 80%

Measured (Simulated)vertical acceptance, 𝛾2Jy [µm]No data

No data

No data

Maximum action of
injected beam(9εy_rms) , 𝛾2Jy [µm]pp
3 y = 3 "y y = 2Jy y~1.6 X

1.41

196.7

<latexit sha1_base64="KAzJZnyrpkQIfzT3U/4YDBax4V0=">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</latexit>

3) Momentum apertureβy* LER

3 mm

1 mm CW off

1 mm CW 80%

Measured (Simulated) momentum acceptance,
p/p0 [%]

0.38 (1.26)

0.53 (1.33)

0.61 (1.11)

Simulated injected beam momentum spread(99%) [%]

~0.32

Raw LER injection efficiency: ~90%.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

20

7-GeV Electron Beam Transport Status

Known sources of hor. emittance blowup1):
1) Incoherent Synchrotron Radiation (ISR)
2) Coherent Synchrotron Radiation (CSR)

1) https://www-kekb.kek.jp/MAC/2022/Report/Iida.pdf

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

21Electron Beam Emittance Status

Reference data:
Run 2022-Nov-5 (J-ARC R56=0)

Horizontal
emittance

Run 2024 (J-ARC R56=0, 0.3)

2022-Nov-5

Verticalemittance

Emittance
blowup2022-Nov-5

BT2

BT1

Sector 5

Sector 3

Sector C

Sector B••

Unexpected additional vertical emittance blowup was observed after BT1.
The blowup is necessary to be mitigated, prior to high-current operation (>1 A).
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

22Local Vertical Bump Study in BTe Arc1-3 & Dispersion Measurement
Local Vertical Bump Study

Dispersion Measurement
N. Iida

ΔX

ΔX

ΔY

ΔY

ΔX

ΔX

ΔY

ΔY

ΔX

ΔX

ΔY

ΔY

No obvious X-Y coupling was observed with horizontal andvertical local bumps (±7mm) in Arc 1 or 2-3.
3/25/2024

Y. Seimiya

Undesigned vertical dispersion was observed inArc1. It is still a mystery.

T. Yoshimoto | The 27th KEKB Accelerator Review

23

HER Dynamic Aperture (βy* = 3~1 mm)

Y. Ohnishi, N.Iida

1) Hor. apertureβy* HER

3 mm

1 mm CW off

1 mm CW 40%

Measured (Simulated)horizontal acceptance, 2Jx [µm]3.89 (3.31)

1.34 (2.77)

1.13 (2.77)

Maximum action of
injected beam (9εx_rms), 2Jx [µm]2) Ver. aperturepyy1.07~1.1~1 X

βy* HER

3 mm

1 mm CW off

1 mm CW 40%

Measured (Simulated)vertical acceptance, 𝛾2Jy [µm]1187 (3982)

649 (973)

712 (973)

1068~3263

1.5~4.5 X

Maximum action of
injected beam(9εy_rms) , 𝛾2Jy [µm]pp
3 y = 3 "y y = 2Jy y<latexit sha1_base64="KAzJZnyrpkQIfzT3U/4YDBax4V0=">AAACoXichVG7SgNBFD2u7/iK2gg2wRCxChMVlUBAtFGrJBoVEgm76yQO7svdSSAGf8AfsLBRQVD8DEHstLHwE8RSwcbCm82CqKh3mJkz595z594ZzTGEJxl7bFFa29o7Oru6Qz29ff0D4cGhdc+uuDrP6bZhu5ua6nFDWDwnhTT4puNy1dQMvqHtLjb8G1XuesK21mTN4VumWrZESeiqJKoYTk4VPFE21WItRWjPlfVCVXW54wmD3LWCxiX5DkKppnNy5ZMrhqMsznyL/ASJAEQRWNoOX6CAbdjQUYEJDguSsAEVHo08EmBwiNtCnTiXkPD9HAcIkbZCUZwiVGJ3aS3TKR+wFp0bOT1frdMtBk2XlBHE2AO7ZC/sll2xJ/b+a666n6NRS412ranlTnHgcGT17V+VSbvEzqeKFLE/qpYoYc6vVlD1js80+tCbGar7Ry+ryWysPs7O2DN1cMoe2TX1YFVf9fMMzx4jRF+Q+P7gP8H6ZDwxE5/JTEfnF4LP6MIoxjBBLz6LeSwhjRzde4Ib3OFeiSrLSlrJNkOVlkAzjC+m5D8AEtGh/Q==</latexit>

3) Momentum aperture

Simulation
0.3%•
3/25/2024

βy*

3 mm

Measured momentum acceptance,
p/p0 [%]

0.69

Simulated injected beam momentum spread(95%) [%]

~0.31

Small ver. aperture and large ver. emittance reduce a raw HER injection
efficiency: ~30%.
T. Yoshimoto | The 27th KEKB Accelerator Review

24

TbT1)-BPM Measurements in HER (βy* = 1 mm)1)turn-by-turnLocal TbT beam survival

D12V2
D12H2

e-

D12V2

D12V4

Shot #2

D12V3
D12H4

Shot #1

ChargeTbT beam survival at a BPM (MQEAE27)

Beam loss
D12V2

Shot #3

D12H3

Turn

50 % of the injected beam is lost within the first two turns by D12 collimator.
• Approximately
beam loss location of the injected beam at the 2nd turn varies in each injection.
• The=> It is consistent with narrow horizontal and vertical dynamic aperture (βy* = 1 mm)
for present injected beam with large emittance blowup.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

25

1st turn
2nd turn

On-Momentum Dynamic Aperture Degradation
due to QCS Cancel-coil Errors[1]M. Kikuchi

Injected
beam

Injectedbeam• QCS cancel-coil errors reduced on-momentum dynamic aperture (2Jx) by ~25%.
• It is crucial for HER beam injection.
[1] M. Kikuchi, “Simulation of the injected beam in HER (2)”, SKB Commissioning meeting, Dec. 22, 2023, https://kds.kek.jp/event/49259/

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

26Synchro-beta Injection (1)M. Kikuchi[1] M. Kikuchi, “Simulation of the injected beam in HER (2)”, SKB Commissioning meeting, Dec. 22, 2023, https://kds.kek.jp/event/49259/

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

27Synchro-beta Injection (2)M. Kikuchi[1] M. Kikuchi, “Simulation of the injected beam in HER (2)”, SKB Commissioning meeting, Dec. 22, 2023, https://kds.kek.jp/event/49259/

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

28Summary
Positron BT:• No bunch charge dependence of beam emittances after DR.
• No bunch-charge dependence of beam emittances. => No wakes, No CSR wakes• There are magnetic errors in Arc3 to explain the horizontal and vertical emittance
blowups.
• BTp-Arc1 modification with 14-mm vertical offset does not degrade beam qualities.
• Raw injection efficiency is ~90%.
Electron BT:• The vertical blowup is necessary to be mitigated, prior to high-current operation.
• Undesigned vertical dispersion was observed in Arc 1.
• QCS cancel-coil errors reduce on-momentum dynamic aperture by ~25%.
=> It reduces HER Injection efficiency.
• Raw injection efficiency is ~40% due to vertical emittance blowup in BT.
=> Synchro-beta injection is an option.
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

29Thank you !

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

30

LER / HER Ring Acceptance SummaryLER
βy*

2Jx (m)γ2Jy (μm)Δp/p0 (%)

Y. Ohnishi

HER
1 mm:
CW OFF

8 mm

3 mm

Feb. 19, 2024

March 4, 2024 March 6, 2024

2.5 x 10-625 σx9.49 x 10-715 σx2.24 x 10-6
23.6 σx4.88 x 10-635 σx1.13 x 10-6
16.8 σx3.37 x 10-6
29 σx

8 mm

3 mm

1 mm:
CW OFF

1 mm:
CW 40 %March 18,2024

Feb. 20, 2024

March 4,2024

March 5,2024

March 18,2024

8.99 x 10-715.0σx3.37 x 10-629 σx3.89 x 10-6
28.9 σx2.92 x 10-625 σx2.11 x 10-6
21.8 σx3.31 x 10-627σx1.34 x 10-6
17.4 σx2.77 x 10-625σx1.13 x 10-6
16.0 σx2.77 x 10-625σxFeb. 26, 2024

Feb. 29, 2024

March 14, 2024

March 18, 2024

1426
6413

1187
3982

649
973

712
973

-

-

-

1 mm:
CW 80 %

βy*

-

-

-

-

Feb. 27, 2024

Feb. 29, 2024

March 6, 2024

March 18, 2024

0.58
1.03

0.38
1.26

0.53
1.33

0.61
1.11

2Jx (m)γ2Jy (µm)

Feb. 20, 2024

Δp/p0 (%)

0.69
1.07

green: tracking simulation with collimator aperture

HER RF Kick example (β∗! = 8 mm)

Δ𝑝/𝑝! = 0.69 %3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

31BTp-Arc1 Bump Height Study @ MSP 8
ECS-Es(kV)

Scheme:Change ver. bump height in BTp-Arc1 to confirm
whether wake (bunch-charge dependence)
effects including CSR ones are significant or not.
Ver. trajectory

Normalized
hor. emittance

Mismatch factor: Bmag

35

BTp1 ver. bump height

MSP8 (OTR)

37.5

Results:
No large bump height dependence of hor. emittances, regardless of the ECS setting (ECS-Es). Measurement: 20231223=> No significant wakes?
3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

32

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

33

Various BTe Emittance Data:
Df(SB3-5) = -4°
J-Arc R56: 0 m

BT1 (WS)

0.8 nC

1.1 nC

1.3 nC

1.5 nC

1.6 nCgex [µm]

43.8±9.4

47.0±6.1

43.8±4.840.9±7.3

47.1±6.9

gey [µm]

40.1±7.2

48.3±12.753.5±6.3

45.3±6.1

49.0±5.1

0.8 nC

1.1 nC

1.3 nC

1.5 nC

1.6 nCBT2 (MSE.16)

2022/Jun/27

gex [µm]

96.6±0.82

117±1.3

126±1.7

122.9±2.2127.9±2.1

gey [µm]104.8±4.2

78.9±1.957.3±1.750.8±1.0

68.5±2.3

1.0 nC

0.9 nC

1.6 nC

2.2nC

J-Arc R56 : 0.3 m

2021/3/26
BT1 (WS)

BT2 (MSE.16)

2022/Nov/5

2.0 nC

1.8 nC

2024/Feb/12

2024/Feb/28

gex [µm]5033.2± 8.0

51.5±15.795.2±15.3

gey [µm]3040.8±11.1

48.0±14.3

81.9±13.4

gex [µm]100164.0±3.8167.3±1.8231.3±6.0

230±58143±3.2

gey [µm]5081.0±5.2

50.5±2.3

127.7±39.3

182±14218±3.5

3/25/2024

T. Yoshimoto | The 27th KEKB Accelerator Review

7834