Beam injection issues
in 2022ab
2022.Feb.21-Jun.22
2022.Dec.13
SuperKEKB Review Committee
N. Iidaon behalf of LINAC beam analysis Groupand Beam injection Task force

2022.Dec.13 ARC, Injection, N. Iida1

Layout of LINAC, BT, Injection to MRe+ beam is injected into the LER via DR:
The injection BG is not almost affected by thebeam condition at upstream of the DR.

e- beam directly injects into HER:
The injeciton BG is directly affected by thecondition of RF-gun, LINAC, and BT.
Injection Points

LINAC

1.1GeV Damping Ring (DR)for positron

Beam Transport line (BT)primary e- for e+: Therminic Gun
SectorB SectorA
Sector1

Sector2

ECS

BT1

Sector3

Sector4

Arc4
BT2

ECS
for e+

Slope2Arc2-3

Sector5

R

SectorC

BCS

LTR

R

LE

Jarc

e- : RF Gun

HEe+ target

BT1 and BT2: Wire scanners(WSs), MSE.10:OTR

BCS: Bunch Compression System (for e+)
ECS: Energy Compression System (for e+)
2022.Dec.13 ARC, Injection, N. Iida

Arc0

BT1

Arc1

MSE.10(OTR)2

Layout of LINAC, BT, Background(BG) monitors in MR
e- beam directly injects into HER

LINAC

R
HE

Damping Ring (DR)for positron

Injection
PointsSectorB
SectorCe+ beam injects into LER via DR.

SectorA

Sector1

Sector2

Sector3

Sector4

e+ target

Beam Transport line (BT)Diamond detectors at QCS in Phase3

BP diamondHER:
QCS(Diamond) BW135

Sector5

LE
R

Jarc

primary e- for e+: Therminic Gun
e- : RF Gun

LER:QCS(Diamond) FW135

Most sensitive to the Background (BG) on Belle2.

MR
Many loss monitors are around the MR.
Belle II

LIN
AC

The signals from the Diamonds and the loss monitors are carefully monitored to keep the BG low.
Some aborts are avoided by stopping injection when the signals are high.

2022.Dec.13 ARC, Injection, N. Iida

3

Contents
I.

Injection summary of 2022ab• Improvement of injections• Injection Issue
1. Emittance growth in the BT lines• e+ Charge dependent of the horizontal emittance• Emittance measurements in e- BT line at BT dump mode
• Possible solution to avoid the emittance growth• Comparison of the miner modification ideas of current e- BT line

2. Injection efficiencies• Dynamic aperture and the emittance of the injection beam
• Injection efficiencies for both rings depend on beam-beam effect

II. Prospects for the future injections
III. Summary
2022.Dec.13 ARC, Injection, N. Iida

4

I. Injection summary of 2022ab••

e- beam needs a tuning around RF gun every a few days.
e+ beam is rather stable thanks to the DR.

④<latexit sha1_base64="vODvUY1+R+fgKV7ByRa18ui3+ig=">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</latexit>

I [mA]HER

The injection efficiency depends on;• the quality of injection beam
• injection parameters such as
septum angle, vertical angle,…
• status of the SuperKEKB ring
• …

Off resonance

by*=
0.8mm

③

HER LER①

1st bunch(BCM)Inj.
2nd bunch(BCM)e↵H [%]
DCCT<latexit sha1_base64="vGA9LfRL9uORPP+DVpcIqd0PH+c=">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</latexit>

1st bunch
2nd bunch Qe [nC]<latexit sha1_base64="l8omQ+oRuViiBNFRH3nE32FzSX4=">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</latexit>②

QCS BW135<latexit sha1_base64="avEtlbzgDRJ4ib/7xBlCq+43/cQ=">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</latexit>[mRad/s]
1st bunch(BCM)Inj.
2nd bunch(BCM)e↵L [%]
DCCT<latexit sha1_base64="KVf0zoPcuXoQZtVcYdlKKnM3jR8=">AAACg3ichVG7SgNBFD2uRmN8RW0ELcSQIAhhIkFFEEQbBQtNzAOyIeyuE13dF7ubQAyxsPQHLKwUBMVKf8HGH7DwE8RSwcbCm82CaFDvMDNnztxz5965sqWpjsvYU4fQ2RXo7gn2hvr6BwaHwsMjWces2ArPKKZm2nlZcrimGjzjqq7G85bNJV3WeE4+WG3e56rcdlTT2HZrFi/q0q6hllVFcokqhSdioq3X1439eEMUPczL5dJG46ggRoulcITFmWeT7SDhgwh82zTDVxCxAxMKKtDBYcAlrEGCQ6OABBgs4oqoE2cTUr17jgZCpK2QFycPidgDWnfpVPBZg87NmI6nVugVjaZNyklE2SO7Zq/sgd2wZ/bxa6y6F6OZS412uaXlVmnoZCz9/q9Kp93F3peKFNE/snZRxoKXrUrZWx7TrENpRagenr6mF1PReoxdsBeq4Jw9sXuqwai+KZdbPHWGELUg8fPD20F2Np6Yiye3kpHlFb8ZQYxjCtP04/NYxho2kaF3j3GFW9wJAWFGmBWSLVehw9eM4psJS594rJRF</latexit>

1st bunch Q [nC]p
2nd bunch<latexit sha1_base64="bSrtq8zR/RERgfxCG5ccbEE+NTA=">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</latexit>

QCS FW135<latexit sha1_base64="x5qgGLoF0Saona3botSI6n5LXBo=">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</latexit>[mRad/s]BP<latexit sha1_base64="8zWbvlVPtBy84Ex43bd1PzCa9bM=">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</latexit>

LER

diamondby*=1mm (basically)2022.Dec.13 ARC, Injection, N. Iida⑤

Improvements① e-: The septa have been operating at
25Hz.
② e+:The fast strip line kicker has beenused to correct the horizontal orbit forthe 2nd bunch③ HER: The injection was improved by
the current-dependent correction of
the horizontal orbit at SLYTE* in HER.
Now the orbit feedback systems areworking well.
To be improved④ e-: Since the injection efficiency ofthe 2nd bunch decreased due to thedrift of the vertical orbit and thehigher emittances of the second
bunch, the two-bunch injection was
temporarily given up.
⑤ e+ charge was decreased to avoid the
BP diamond aborts.
5Df=-4deg

Real tuning

Improvements of injections
1. Injection tuning

Scannedin ±1.5°• The RF phase in LINAC(SB_3-5) tunings are effective
to injection efficiencies and beam backgrounds.
• Flourecent screen monitors were replaced with OTR monitors in BT line
(See talk on “BT” for detail)• Especially, MSE.12 is always used to check the energy spread.
• It is expected that the measured energy spread will be quantified.

• An SRM in BT line since the BT dump mode operation in 2022.Oct (See talk on “BT” for detail)• It is effective for monitoring beam size, emittances non-destructively.
• It is expected that the measured beam size will be quantified.

• Injection tuning by septum with 25Hz continuous operation① (See talk on “BT” for detail)• The angle (and position) of the septum no longer needs to be adjusted as often as before.
• The four septum outputs depend on the temperatures of the output cables or/and the power supplies.

• Collimator tuning in the MR is one of items for the injection tuning.
(See talk on “Belle II” for detail)2. The horizontal orbit FB at SLYTE* in HER ③ (See talk on “Optics issues” for detail)• It was very effective in preventing decrease in injection efficiency which is not attributed
injection conditions.

3. The fast strip line kicker in RTL has been used to correct the horizontal orbit of
the 2nd bunch ② (See talk on “BT” for detail)2022.Dec.13 ARC, Injection, N. Iida

6

Injection issue
1. Emittance growth in BT line••e+ BT: The charge dependence of the horizontal emittance is observed.
e- BT: CSR (Coherent Synchrotron Radiation) effect has been studied as a cause other than ISR (Incoherent Synchrotron Radiation)
The horizontal emittance growth was observed to depends on;
A)
The RF phases, sub-boosters in sector 3, 4, and 5 in LINAC
B)
Beam charge
C)
Twiss parameters of Arc1
D)
Dispersion pattern in the Arc1 in BT
E)
The vertical offset from median plane of the bend chambers in the Arc1
• Vertical emittance growths for both lines are still problem•

Comparison of the miner remodeling of current e- BT lines
1.
2.
3.

2.

Make the new straight BT line along the AR-BT line
Exchange the chambers in the BT Arc1~3 to narrower chambers to cancel the CSR effects.
Install the e- ECS

Injection efficiencies for the main rings••

Dynamic apertures and emittances of the injection beam
Injection efficiencies for both rings depend on beam-beam effect

3. Two-bunch injection in HER (See talk on “LINAC” for detail)•The injection efficiency of the 2nd bunch occasionally decreased due to;••the drift of the vertical orbit
the higher emittances of the second bunch

4. The aperture improvement around the injection point (See talk on “BT” for detail)5. DR low emittance optics had been failed twice. → not resolved yet•

There may be some discrepancy about the DR optics between design and real machine.

6.

Test of “Auto-tuning” of LINAC beam (See talk on “BT” for detail)7.

The wake field cancellation with orbit bumps in the LINAC (See talk on “LINAC” for detail)2022.Dec.13 ARC, Injection, N. Iida

7

1. Emittance growth in the BT line
Previous MAC in 2021.9

1nC③
In 2021ab,
we did not measure
the horizontal
emittance in BTp2.
This elementaryparameter should bemeasured.

The reason why
the horizontal
emittance growth
between BTp1 andBTp2 is not
resolved.
The dispersion leakfrom ECS at SY3will be corrected byinstallation of aquad at the centerof chicane in the
ECS
in Aug. 2021.
④
The verticalemittance growth
can be lower by
installation ofresidual skew
quads for thecorrection of skew
quad components
from the bends inArc2-3.

2022.Dec.13 ARC, Injection, N. Iida

Jun. 8 Jul. 5
Mar. 26⓪Synchrotron
radiation~+7µm

gex=100µm
gey=50µm
at BT2 on Mar. 26⓪
Synchrotron
radiation → Next slide(30→76µm)①
The deviation of the horizontal
emittance by changing
dispersion pattern is small.
The emittance growth due to
CSR effect is not confirmed yet.

② The vertical emittance
growth should be resolved.

Jul. 5
Jun. 8Mar. 26

The slit of injection channel (P.28):
height=5mm, which looks wide enough.
by(QI4Eend)=31.85m
gey= 50µm→6sy=2.1mm
gey=100µm→6sy=2.9mm
gey=150µm→6sy=3.5mm
gey=200µm→6sy=4.1mm• These horizontal
emittance growths
are not resolved yet.
• We considered thata part of them arecaused by CSR.
• For confirming it,
we measured thecharge dependenceof emittances.

8

Charge dependence of emittance in BTp
Charge of 1st bunch

Measured emittance at BT1 and BT2

Charge of 2nd bunch“Raw injection efficiency” of 1st bunch“Raw injection efficiency” of 2nd bunch* “Raw injection efficiency” means injection efficiency corrected the beam life.

••
e+ horizontal emittance was increased,
which is suspected due to CSR effect.

2022.Dec.13 ARC, Injection, N. Iida•

The injection efficiencies decreased as the beam
charges of the injection beam increased.
The e+ charges had been reduced to less than 2.6nC to
avoid beam aborts.
9w
By t h eay,“Raw injection efficiency”

Current of the injected bunch measured
by a turn-by-turn BPM in the LER

LER

MQEAP22“Raw” efficiency
75%
~0.64
50%

~1ms

“Raw injection efficiency” of 1st bunch“Raw injection efficiency” of 2nd bunch

10ms“Raw injection efficiency” had been measured too early (~100turns).
It will be changed just before the next injection after LS1.

We have calculated the "raw injection efficiency” using theBCM(Bunch current monitor) that measures the increment of
the bunch charge before and after the injection. It should,
however, be noted that this may overestimate the injection
efficiency because the BCM takes data at 100 turns after the
injection while the injected beam decays in longer period.

2022.Dec.13 ARC, Injection, N. Iida

10

Emittance measurements in e- BT line at
BT dump mode
• We had a study time for e- BT for one week from Oct.31 to
Nov.7• It was done in “Fuji mode” in which the tunnel work in the half northarea of the ring can be done.
• Electron charge of 0.9~2.2 nC was available while the positron beam
was not available because of works in the DR and power saving.

2022.Dec.13 ARC, Injection, N. Iida

11

Summary of the previous measurements of emittance and bmismatch(BMAG) in e- BT：ge with WS●●：gex measured with OTR

1.0~1.1nC●：gey measured with OTR●：ge with SRM+gated camera
•

gex
(µm)

MSE.10BT1••
MSE.16

BMAGx

gey
(µm)

●

BMAGy
BMAG:
Optical mismatch factor

•
•

●

•

The others are measured in2020.Dec.22.
are measured in 2021.Mar.26.
There are still uncertainties inabsolute values because an errorof the quadrupole strength used in
the Q-scan turned out to give asizable effect to the measured
values in the study. We plant toprecisely measure the quadrupoleerrors using the beam.
Anyway, it is considered that;
The horizontal emittance growthoccurs in the Arc1.
The vertical emittance growthoccurs in the Arc1 and Slope2.

In the study we mainly focused whether thecause of the horizontal emittance growth
could be attributed to CSR or not. 122022.Dec.13 ARC, Injection, N. Iida

Study of CSR in BT-Arc1 in Nov.2022• Emittance growth between BT1 and MSE.10

Dump

e- beam
LINAC

Unfortunately, the beam
dump in BT is in front of
the BT2 monitors.
So, we measured theemittance at MSE.10(OTR).

BT

2022.Dec.13 ARC, Injection, N. Iida

BT-Arc0

SRM
BT1(WS1)

BT-Arc1 MSE.10(OTR) BT2(WS2, MSE.16(OTR) )13

Study of CSR in BT-Arc1
1. Emittance growth dependenceA) RF phase of SB_3~5
B) Charge• 0.9, 1.6, 2.2 nC

C) Twiss parameter of Arc1 using,• QAF1E, QXD6E

D) Dispersion pattern• 2 patterns in the Arc1

E) Vertical beam offset from the median plane of the chamber• Making vertical bump in the Arc1

2022.Dec.13 ARC, Injection, N. Iida

14

Energy distribution dependence on the RF phasein SB_3~5
2.2nC
Measurement
MSE.12

Simulation
Df=-4deg

Df=-2deg

Df=-2deg

Df=-4deg

Df=0deg
Df=0deg
Df=+2deg
Df=+2deg

Df=+4deg

Df=+4deg

T. Kamitani2022.Dec.13 ARC, Injection, N. Iida

15A) PF phase and B) charge dependence on transverse emittances (measurement)* zero RF phase gives the minimum energy spread of a beam.

Emittance measurement:
BT1

MSE10

Simulations (ELEGANT)
BT1
MSE10

T. Yoshimoto

ISR+CSR
ISR
BT2

2.2 nC

HER

Linac

BT
1

MSE10

Dependence on RF phaseand bunch charge ( 0.9, 1.6,
2.2 nC), was measured inthis study.
=>
For each bunch charge,
large emittance growths
between BT1 and MSE10
were observed.

1.6 nC

0.9 nC

2022.Dec.13 ARC, Injection, N. Iida•16

CSR effect explains large emittance growth at a phase of ~2 deg, except the 0.9 nC case.

B) Bunch charge dependence

The measured horizontal emittances
clearly show charge dependency.

MSE.10

DfSB_3-5 (deg)Simulations(parallel plate model)

DfSB_3-5 (deg)Measurements

2.2 nCgex (µm)

gex (µm)

gex (µm)

gex (µm)

Measurements

1.6 nC

0.9 nCDfSB_3-5 (deg)Beam charge (nC)

gex (µm)

ISR＋
CSR

DfSB_3-5 =-2 deg

DfSB_3-5 =6 deg

Beam charge (nC)

Observed emittance growth is consistent with the CSR effect, but
the measured blowup is still larger than that of the simulation.
2022.Dec.13 ARC, Injection, N. Iida17C) Changing Twiss parameters of Arc1
T. Yoshimoto

Measurement
Normalized emittance [µm]MSE.10，2.2nC
Df(SB_3-5)=0°

Operation

SAD Simulation

X

•

Y

K1 @ QAF1E

•

QXF6E

Arc1
MSE.10
QAF1E

Normalized emittance [µm]QAF1E: K1=0.12
Operation

XY
K1 @ QXF6E

D) Changing dispersion pattern in the Arc1(a)

The horizontal emittancemeasured after the Arc1
depends on the Twiss
parameters in the Arc1.
The tendency is reproducedwith simulation.

(b)

T. Yoshimoto

gex
[µm]

Meas.
BT1

Meas.
MSE.10

Sim.

(a)

34±9

246±6

100

(b)

34±6

240±5

75

•

•
2022.Dec.13 ARC, Injection, N. Iida

The lower dispersion optics will be simulated.

The measured horizontal
emittances were almost
same for the two
dispersion patterns.
In simulation, (b) gives asmaller emittance.
18E) Vertical bump orbit

T. Mori, M. Kikuchi

T. Nakamura (J-PARC)• According to the parallel conducting
plates model, CSR wake fields are
reduced when the beam passes
through the offset position from themedian plane of the plates.
• It has been observed that thehorizontal emittance has significantly
reduced when the vertical bump orbit
gets closer to the top or bottom wallof the beam chamber.
• Quantitative explanation using themodel is in progress.

19E) CSR shielding with narrower ducts

T. Yoshimoto

Conditions in simulations:• Linac RF phase: 86 deg (for minimum energy spread)• CSR model: steady-state parallel-plate CSR model• Bunch charge: 2 nC
• Beam energy: 7 GeV• Jarc R56: 0.3

BTe1

BTe2

Model

x/y nemit (pi.um.rad) @ BTe1

x/y nemit (pi.um.rad) @ BTe2

ISR + CSR + RFWAKE(h=32 mm)26/12

129/12

ISR + RFWAKE

14/10

65/11

ISR + CSR + RFWAKE(h = 10 mm)

25/11

91/11

•
2022.Dec.13 ARC, Injection, N. Iida

In the BTe, lower duct heights (h = 10 mm) partially mitigate CSR effects.

Narr
ow g

ap i s

good

20

.

Possible solution to avoid the emittance growth
The Horizontal emittance growth
There is a high possibility that CSR is one of the causes in addition to ISR.

• Current e- BT line
1.
2.
3.

Operate with the vertical orbit near the chamber wall
Optimize the Twiss parameters in the Arc1
Optimize the dispersion pattern of the Arcs.

Seen from the side
Quad

Bends

Quad

beam

• Miner modification of current e- BT line
0.

Realign the bending magnet of the Arc to pass the beam near the top or the bottom wall of the chamber.
It is necessary to remake the bellows chamber at both ends of the bend

1.
Exchange the chambers in the BT Arc1~3 to narrower chambers to cancel the CSR effects.
2.
Install the e- ECS
3.
Make the new straight BT line along the AR-BT line
→The beam emittances about the above 1.~3. patterns were estimated;• Horizontal emittance• Longitudinal emittance• e+ BT line
• CSR measurement is planned. → “BT” talk2022.Dec.13 ARC, Injection, N. Iida

21

Horizontal emittance

M. Kikuchi

Microbunching in e- BT
Rough estimations were done to study
parameter dependence of the CSR effect.

d
z

d
z

Microbunching is caused by thispart standing in the phase space.

dzzThis model assumes CSR can be represented by an integration of the spectra exceeding the threshold(P>th).
Betatron oscillation caused by CSR at bends can be estimated by taking into account the betatron phaseand its action is defined as “2JCSR Score”. P>th is very large in Arc1.→CSR effect is expected to be large at Atc1.

22

Horizontal emittance••

Tracking simulation

Both of the measurementand 2JCSRscore has thesame tendency;
the emittance increases in
the region where Df3-5 isnegative while decreases
for positive Df3-5.

Narrowing chamber heights
is very effective to suppress
the CSR for both of current
and the new BTs.

Narrowing chamberheightse(6 mm in Arc1~3)< e (10 mm in Arc1~3)< e (6 mm in Arc1 only)<< e ( 32 mm in all Arcs (Now))
2022.Dec.13 ARC, Injection, N. Iida

23

New beam transport line (1)T. Yoshimoto• Purpose: ISR & CSR suppression at Arc1 => A new straight line is introduced instead of current Arc1.
• Simulation with ISR & CSR is essential to evaluate the emittance improvements.
Initial distribution

Conditions in simulations:• x/y nemit: 30 um.rad• Bunch charge: 2.2 nC• Beam energy: 7 GeV• Linac RF phase: 86 deg (for minimum energy spread)• CSR model: steady-state parallel-plate CSR model* *New optics is calculated with a full gap of 3 cm for all bending magnets.
• Full x/y aperture: 4 cm

Current beam transport

straight beam transport

HER

straight beam tran
sport
(design)presetra nt b
ns ea
po m
rt

Arc1

2022.Dec.13 ARC, Injection, N. Iida

Prelimin a r yCurtesy: M. Kikuchi

24

New beam transport line (2)• x/y nemit: 30 um.rad• Bunch charge: 2.2 nC

Current beam transport

T. Yoshimotostraight beam transport (design)

ISR+CSR
ISR

ISR+CSRISR
no ISR, no CSR

no ISR, no CSR• New straight beam transport line caneffectively suppress CSR and ISR effects
thanks to fewer and weaker bending
magnets, as expected.
• Bending ducts with a full height of 30 mm
cannot completely suppreess CSR.
2022.Dec.13 ARC, Injection, N. Iida

Simulation

gex [µm] at the end of BT

ISR

CSR

present BT

Off

Off

53

36

On

Off

104

46

On

On

126

63

new BT

25

Longitudinal emittance
1. Current BT, no ECS
SB_3-5 Df scan

Df=-4deg

Simulation

The simulation isconsistent with the usual
operation tuning that
Df=-4 deg is the best
injection.

Df=-6 deg

Df=-4 deg

2022.Dec.13 ARC, Injection, N. Iida

Real tuning

Scannedin ±1.5°

Df=-2 deg

Df=0 deg

Df=2 deg

Df=4 deg

Df=6 deg

26

Longitudinal emittance

Simulation of Injection
The tolerance of injection tunings to the HER(by*=1mm) are simulated.

Y. Ohnishi

by*=1mm<latexit sha1_base64="c883jE2U4o31ZYnygODOgfhAQfc=">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</latexit>

c
360
f 360
z[mm] = 1.46

z=

=

95％

±13°
Z: =±19mm

d:±0.25％

Initial particles which are tracked
from LINAC via the BT line.
gex=118µm
gey=12µm

2022.Dec.13 ARC, Injection, N. Iida

Aperture of HER is drawn
using the width where theinjection efficiency is morethan 95%.
Design values of HER are
assumed.
sz=4.9 mm
27
sd=6.3e-4

Longitudinal emittance
Injection efficiency

2Jz of injection beam

ry
a
n
i
m
Preli

Result:e- ECS• Even with R56=-0.6m Vc=70MV, the effect of lowering 2Jz can be seen.
• Investigation with a parameter of R56 = -1.0m will be done soon.
New straight BT line
• For this longitudinal emittance study, it is better than the current BT a little.

2022.Dec.13 ARC, Injection, N. Iida

28

P

ry
a
n
i
relim

Comparison of proposed improvement schemes
ISR

CSR

Longitudinalemittance

Cost

Construction
periodCurrent BT, no ECS

Large

Large

Just in00Current BT, ECS
R56=-0.6m, MV=70MV

Large

Larger

Small

?

?

Small

Small

just in?

?

very small

no effect ?

?

?

Current BT, ECS
R56=-1.0m, MV~100MV ?
New BT, no ECS
New BT, with ECS
with narrow chambers in Bends no effect• More simulation studies are on going.
• We should also study about βy*<1mm2022.Dec.13 ARC, Injection, N. Iida29

2. Injection efficiencies
Initial particles

HER

Assume:gex=250µm
gey=45µm

Simulation
97%

98%

Initial particles which are tracked
from LINAC via the BT line.

88%
TbT-BPM

Measurement

Y. Ohnishi

100%
60%

Real injection efficiency is much worse than thesesimulation.
• The injection beam are worse ?
• Emittances, narrower aperture of theinjection region, …
AND• The dynamic aperture of HER is worse ?

55%

LER

Injection tunings
Δ𝑥$% = −0.2𝑚𝑚
injection phase: Δ𝜙 = +8∘ Δ𝜃$% = 0.04𝑚𝑟𝑎𝑑

Initial particles

𝛾𝛽𝜀! =105 𝜇𝑚 𝛾𝛽𝜀" =4.1 𝜇𝑚

Simulation

px

78%
x (m)

2.6nC
𝛾𝛽𝜀! =250 𝜇𝑚 𝛾𝛽𝜀" =45 𝜇𝑚

71%

Simulation
after injection tuning

Measurement at BT2, 2.6nC :gex=250µm
gey=45µm

py
y (m)

Δ𝑝
𝑝!
2022.Dec.13 ARC, Injection, N. Iida

Measurement

LER

TbT-BPM
MQEAP22“Raw”
efficiency
75%
~0.64
50%

z (m)

~1ms

10ms

•
•

Beam loss in the simulation after 1000 turns
does not reproduce the actual injection
efficiency.
The beam loss after the injection is a serious
problem to accumulate higher current.
30

Dynamic apertures

Simulation
QCS Aperture +Collimators + CW On
no machine error

Y. Ohnishi

HER

HER
Real: 32 min

LER
Real: 6 min

The lifetimes of simulations donʼt reproduce the real, especially for HER.
2022.Dec.13 ARC, Injection, N. Iida

31

Injection efficiency depends on beam-beam effectInj. single→collisioncollision→single

LER

HER

“Raw” inj. efficiency [%]↓↑ 90→80
80→90↑ 50→40↓
40→50

Inj. efficiency [%]↑↓ 30→40
40→30↑ 40→15↓
15→40

ey [pm]↑↓60→25
25→60

40→45
45→40

ex [nm]

3.5

4.6

↑
↓8→6
6→8

↓
↑30→3232→30

lifetime [min]2022.Dec.13 ARC, Injection, N. Iida

The quantitative evaluation should be done.

32II. Prospects for the future injections
LER
MQEAP22

It is said this pattern issimilar to the shape of oneof the Belle II background,
duration.

~0.64
50%
~1ms

LER

InjEff~40%“Raw”
efficiency
75%

10ms

2021.Dec.23, by*=1mm
HER

75%
↓
40%

Y. Funakoshi

Injection efficiency fromBCM
Injection efficiency from
DCCT with correction ofbeam loss due to lifetime

InjEff~45%

The injection efficiency from DCCT with correction of beam loss lifetime is lower than “Raw injection efficiency”.
We used injection efficiencies which are corrected the lifetimes.
2022.Dec.13 ARC, Injection, N. Iida

33

Example of parameters for L= 1 x1035cm-2s-1

Y. Funakoshi

LER

HER

LER

HER

# of bunches

2345+12345+1

Luminosity

1.0 x 1035 cm-2s-1

1.0 x 1035 cm-2s-1

Itotal

2.08A

1.48 A

2.78 A

1.65 A

Ibunch0.89mA0.63mA

1.18mA0.70mA

by*

0.8mm

0.8mm

1mm

1mm

sy*

0.154µm

0.154µm

0.211µm

0.211µmsz

6.49mm

6.35mm

7.26mm

6.51mmBeam lifetime

3.4min.

14.8min.

4.7min.

16.9min.

•••This parameter list was made based on a high bunch current collision study.
We will aim to achieve the parameter list.
In the process of aiming at the parameter set, we will need to study various issues and aim at theluminosity with solving issues found and with modifying the parameter set.

2022.Dec.13 ARC, Injection, N. Iida

34

Required injection charge

Many parameters assumed and see
the backup slide for detail.

LER

102nC/s -> 3nC, 2bunch,
25Hz InjEff=68% (by*=0.8mm)

Y. Funakoshi

HER

by*=0.8mm

16.7nC/s -> 2nC, 2bunch,
25Hz InjEff=17% (by*=0.8mm)

by*=1mmby*=1mm

16.2nC/s -> 2nC, 2bunch,
25Hz InjEff=16 % (by*=1mm)

99nC/s -> 3nC, 2bunch,
25Hz InjEff=66 % (by*=1mm)••

by*=0.8mm

To achieve the luminosity of 1x1035 cm-2s-1, the injection efficiencies should be more than
68% for LER and 17% for HER.
It is difficult to achieve the injection efficiency of 68% for LER without improving
the emittance of injection beams and extending MR lifetimes
LER

2021.Dec.23, by*=1mm HER
Injection efficiency fromBCM

InjEff~40%<<68% !!
2022.Dec.13 ARC, Injection, N. Iida

Injection efficiency from
DCCT with correction ofbeam loss due to lifetime

InjEff~45% >17%
for both bunches !
35

III. Summary• Injection improvements• Some improvements and efforts were effective to realize higher injection efficiency.
• The new beam monitors, OTRs and SRM in the BT are very useful for studies as well
as operations.

• Issues• Observed horizontal emittance growth is consistently explained by ISR and CSR
effects.
• The source of vertical emittance growth is not understood yet.
• Extensive simulation study as well as beam study is necessary to make decision of
remodeling the BT lines or not.
• Narrow chambers, e- ECS, New straight BT line

• The bad injection efficiency may come from the emittance growth of the injection
beam and/or the larger dynamic aperture of the HER.
• The investigation of the beam loss during 1,000 turn in the LER is urgent. Improvementof injections are vitally importance to achieve the luminosity of 1x1035cm-2s-1.
2022.Dec.13 ARC, Injection, N. Iida

36• To be continued to the new international task force forinjection….

2022.Dec.13 ARC, Injection, N. Iida

37

Backup slides

2022.Dec.13 ARC, Injection, N. Iida

38

1. Injection summary

Emittances of injection beams
Sometimes the horizontal emittance(gex) became ~150mm,
but it recovered after a few days. Itʼs still a mystery.

LER

2022.Dec.13 ARC, Injection, N. IidaHER

The emittances of e- beam had been
gradually larger at the last 2 weeks,
which caused the lower injection efficiency.

39

1. Injection summary

Septum 25Hz

Off-momentum
Off-momentum

2022.Dec.13 ARC, Injection, N. Iida40

2. The horizontal orbits at SLYTE1 in HER

The orbit FB at SLY* in HER

The horizontal orbits at SLY* in the KEKB
rings affects to the injection.
Not only the injection efficiency and BG
were improved, but the fluctuations werealso reduced.

Orbit correction was performed using Local bump to compensate
for the current dependence of the horizontal orbit in SLY.
Now the orbit feedback system was working.
H. Sugimoto, Y. Ohnishi2022.Dec.13 ARC, Injection, N. Iida

41

Current dependent orbit offset @ SLYT**E
KCG: 2022_05_17_0900_Yoshino_Egawa

Simulation:

Corrected
by Ohnishi-san〜20µm

DX(SLYTLE1)=DX(SLYTLE2) = -20µmの場合のβ beat
コリメーターでのsy：+14%

Injectionpoint

βy* smaller<latexit sha1_base64="/wUZA9hnKPkIoqH2z219EuTGqq8=">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</latexit>yyby*=1.0→0.8mm
by*が絞れるので、Luminosityは上がる
傾向。

SLYTRの変化量は⼩さいため、六極ペアでキャン
セルされない2022.Dec.13 ARC, Injection, N. Iida

・⼊射点でのβyが設計値の1.3倍(BMAG=1.035)になる
・コリメータでのビームサイズが14%増⼤する
・HER内のβ関数が乱れる
42
等より、⼊射効率が悪化していた。実際には70％→60％であった。(前⾴)before septum 25Hz

The D08 room temperature dependence ofthe cable temperature had various
coefficients due to the repetition of septum.

after septum 25Hz

Septum 25Hz

By the septum operation with keeping 25 Hz,
the injection tuning was easier.
2022.Dec.13 ARC, Injection, N. Iida

The cable temperatures which affects to the septum outputs
43
now has a simple dependency on room temperature.

3. Fast strip line kicker for the e+ 2nd bunch in RTL“Raw” injection efficiency of #1“Raw” injection efficiency of #2
The efficiencies have been almost
same since the kicker worked.

Extraction kickers
The fast strip line kicker

DX at BPM2

DX at BPM1

The fast strip line kicker ON

DX: Horizontal orbit difference (X_2-X_1)
ByARC,
improvingthetiming system, the fluctuation of the horizontal orbits
2022.Dec.13
Injection, N.
Iidabecame very small.

BPM1

BPM2

44

1. Emittance growth dependencegex (µm)

gey (µm)

gex (µm)

2.2 nC

1.6 nCgey (µm)A) RF phase in SB_3~5

Measurements
MSE.10

DfSB_3-5 (deg)

DfSB_3-5 (deg)

0.9 nCBT1

gey (µm)

DfSB_3-5 (deg)gex (µm)gex, gey (µm)

DfSB_3-5 (deg)

DfSB_3-5 (deg)In the (‒) region, gex has a parabolic dependence.
In the (+) direction, there is a region with smaller
emittance.
• The correlation with RF phase is small between gex
and ARC,gey atBT1 andgey at MSE.10.
2022.Dec.13
Injection,
N. Iida••gex, gey (µm)

DfSB_3-5 (deg)

DfSB_3-5 (deg)BT1

DfSB_3-5 (deg)45A) PF phase and B) charge dependence on transverse emittances (measurement)
T. Yoshimoto

2.2 nCBeam optics:

Beam transport lattice:

BT MSE101Linac

1.6 nCHER

BT2Emittance measurement:
BT1
MSE10

Sec. 3-5 RF phase and bunch charge (0.9, 1.6, 2.2 nC)
were changed in this study.
=>
For each bunch charge,• large x/y emittance growths between BT1 and MSE10 were observed.
• RF phase of max. horizontal emittance was ~ +4 deg.

0.9 nC=> Is this CSR effect?

2022.Dec.13 ARC, Injection, N. Iida46
* zero RF phase gives the minimum energy spread of a beam.

A) PF phase and B) charge dependence on transverse emittances (measurement)
Emittances at BT1 and MSE10 (downstream)

BT1

MSE10

Lon. phase space dist. at BT1 and MSE10 at zero RF phaseSecs.3-5
RF Phase:

PBTE(Before BT1)

MSE6
(in BT1)

T. Yoshimoto
MSE10

2.2 nC86 deg.

1.6 nC
87 deg.

0.9 nC.

•••

Linac RF phase changes longitudinal phase distribution.
A specific phase gives steep longitudinal histogram inside strong bending magnet. => large emittance growth
In the simulation for a 0.9-nC bunch, there is no double peak structure in longitudinal phase before BT1, although it depends onbunch2022.Dec.13
length. =>ARC,
it would
give
less CSR effect. However, the measured results shows a large emittance growth. This discrepancy
Injection,
N. Iida47
is under investigation.

Longitudinal phasespace along the e- BT

2022.Dec.13 ARC, Injection, N. Iida

48

Optimization of the BT optics to minimize the CSR induced emittance growth
M. Kikuchi

2022.Dec.13 ARC, Injection, N. Iida

49

Longitudinal acceptance in HERThis DA plot should be
used the injection
distribution.

by*=1mm
Crab Waist=40%
QCS Aperture + Collimators
No machine error

by*=0.3mm
Crab Waist=0%
QCS Aperture
No machine error

TDR

Y. Ohnishi

Y. Ohnishi

95％±0.25％

50％±0.43％①
2Jx=5x10-7、When exHER=4.6nm,
DX/sx<10.4d②d/sd =6.7, sd=6.3x10-4より、d<0.42%

2022.Dec.13 ARC, Injection, N. Iida③
In the injection simulation,
The beam energy where the injection
efficiency becomes 50% is d=±0.43%,
which is consistent to the left figure.

The DA of TDR is the value atby*=0.3mm, which is smaller
than DX/sx= 10.4 and theincidence efficiency is low.
So we decided to use
synchrotron injection scheme for
HER at the time.

50

Longitudinal emittance
1. Current BTe line

Injection efficiency

2. Current BTe line
+ECS(R56=-0.6,
Vc=70MV)2Jz of injection beam
3. Current BTe line
+ECS(R56=-0.6,
Vc=40MV)

4. New straight BTe line

2022.Dec.13 ARC, Injection, N. Iida

Result:e- ECS• Even with R56=-0.6m Vc=70MV, the effect of lowering 2Jz
can be seen51
• Investigation with a parameter of R56 = -1.0m is planed.

Simulation of injections

Y. Ohnishi
Simulation

Initial particles

HER

97%

98%

88%
TbT-BPM
100%
60%
55%

LER

Initial particles
px

Δ𝜙 = 8∘𝛾𝛽𝜀! =105 𝜇𝑚 𝛾𝛽𝜀" =4.1 𝜇𝑚

Δ𝜙 = 8∘78%

2.6nC
𝛾𝛽𝜀! =250 𝜇𝑚 𝛾𝛽𝜀" =45 𝜇𝑚

x (m)

71%
Δ𝜙 = 8∘py

Δ𝜙 = 8∘

y (m)

z (m)

2022.Dec.13 ARC, Injection, N. Iida

Simulation
after injection tuningΔ𝜙 = 8∘

LER

Δ𝑝
𝑝!

Injection tunings
Δ𝑥$% = −0.2𝑚𝑚
injection phase: Δ𝜙 = +8∘ Δ𝜃$% = 0.04𝑚𝑟𝑎𝑑

Simulation
Injection efficiency : QCS aperture + collimators

Real injection efficiency ismuch worse than thesesimulation.
• The emittances of
injection beam are worse ?
OR/AND• The dynamic aperture of
HER is worse ?

TbT-BPM
MQEAP22

~1ms

“Raw”
efficiency
75%

•

~0.64
50%

•

10ms

The simulation can not
reproduce the real injection.
It is serious problem where
the beam loss after the
injection comes from.
52

Assumption in calculation of required injection charge
Y. Funakoshi• Required injection charge (𝐼!"# 𝐼𝑛𝑗𝑒𝑓𝑓 [C/sec])((%&' )#'*

𝐼#$% 𝐼𝑛𝑗𝑒𝑓𝑓 = '&• Specific luminosity• We assume relatively high values achieved in the high bunch
current study.

• Number of bunches

1.75=4/7
Assumed curve for specific luminosity
Bunch current ratio= 1.27

• 2345 + 1 (pilot bunch) (2 bucket spacing)• Beam current ratio

Bunch current ratio= 1.61
30 bunchcollision• Assume that the ratio is dependent on bunch current product• Required total beam currents• Use the above parameters and calculate required total beam
current to achieve luminosity of 1 x 1035/cm2/s• Two cases: by*= 1mm and 0.8mm (In case of by*=0.8mm, specificluminosity is assumed to increase by 25%.)• Beam lifetime• Touschek and vacuum lifetimes are considered. Touschek is dominant.
• CT and CV was determined𝑛2experimentally. Luminosity lifetime is ignored.
𝜏 +,-./0*1 = 𝐶+𝜀 𝜀 𝜎𝐼2*34 5 6 7from streak camera
1
Values 2022.Dec.13
in physics
runfrom specific luminosity
ARC,
Injection,
𝜏83/--4N.=Iida𝐶8
𝐼2*34
w/ assumption of sy*(LER) = sy*(HER)53

2022.Dec.13 ARC, Injection, N. Iida

54