Recent status of
LINAC, DR, BT, andInjection
1/Mar/2021
BPAC
N. Iidafor the Beam Injection TF
LINAC: Injector for 4 rings(HER, LER, PF, PF-AR)
DR: Damping Ring for e+
BT: Beam Transport line for HER and LER
N.Iida BPAC, 1.Mar.2021

1B) Layout of LINAC, BT, Injection 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.
LINAC

1.1GeV Damping Ring (DR)for positron

Jarc

primary e- for e+: Thermionic Gun
e- : RF Gun
BCSSectorB SectorA
Sector2

Arc4

LTR

ECS

BT1

Sector3

Sector4

BT2

ECS
for e+

Arc2-3

Sector5e+ target+ Flux Concentrator(FC)

N.Iida BPAC, 1.Mar.2021

R

R

Sector1

Beam Transport line (BT)HE

LE

SectorC

Injection Points

Green: Emittance measured with wire scanners(WSs)
BCS: Bunch Compression System
ECS: Energy Compression System

Arc0

BT1

Arc1
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
e+ target

Sector2

Sector3

Sector4

Sector5

LE
R

Jarc

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

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

MR
Many loss monitors are around the MR.
Belle IIHER:
VXD(Diamond) BW135

LER:
VXD(Diamond) FW135

Most sensitive to the Background (BG) on Belle2.

LIN
AC

N.Iida BPAC, 1.Mar.2021 The signals from the Diamonds and the loss monitors are monitored to keep the BG low.

Some aborts are avoided by stopping injection when the signals are high.

3Contents
1. Injection summary of 2020c
2. Beam quantity and quality in LINAC
3. Injection efficiency
4. 2-bunch injection
5. Collaboration with Belle II about injection

N.Iida BPAC, 1.Mar.2021

4

Injection summary of HER 2020c

Injection efficiency
calculated from BCM*
for the first ~100 turns
is useful as it isindependent on the
beam lifetime.
*BCM:Bunch Current Monitor

Look at the lower edgein the injection
efficiency plots.

Total currents

Collimatorexchanged
in LER

The injection efficiency (BCM)
achieved 60% at by*=1mm !

40%Charge achieved
1.6 nCat BT end

Anticorrelation
betweeninjection
efficiency andemittance

Measuredemittanceat BT1
Backgroundin VXD
diamond
N.Iida BPAC, 1.Mar.2021

Orbit at BT
end is corrected.

The variation of
VXD shows theBG from injection
5

Injection summary of LER 2020c
Total currents
The injection
efficiency(BCM) had
been more than 90%
even at by*=1mm

Collimatorexchanged
in LER

Injection efficiency (BCM)
dropped less than 90%
as the optics of LER changed.

Look at the minimumedge in the injection
efficiency plots.

Achieved
2.0 nCat BT end

90%

Flux Concentrator
On/OffInjection BG larger
The variation of
VXD shows theBG from injection
N.Iida BPAC, 1.Mar.2021

6

Injection summary of 2020c• HER• The BCM injection efficiency had been less than 40% at by*=1mm.
It was improved to 60% at the end of 2020c.
• It will be discussed later.

• The BG from injection is small, which is no problem now.

• LER
• The BCM injection efficiency had been about 90% even at by*=1mm,
but from December, it became 50~80%, after the change of optics
for the LER.
• The BG from injection is large, which is one of big problems.

N.Iida BPAC, 1.Mar.2021

7

2. Beam quantity and quality in LINAC• e• e+N.Iida BPAC, 1.Mar.2021

8

Orbit and Charge from LINAC to MR in 2021a
LINAC
head

PositronBT
end
2021/2/22 1:10:40

LINAC
head

Electron

Orbit X [mm]Orbit X [mm]Orbit Y [mm]Orbit Y [mm]Charge [nC]

Charge [nC]e+ TargetDR
N.Iida BPAC, 1.Mar.2021

1st: 2.6nC
2nd: 2.2nC
at BT end

The charge amount is kept
constant by feedback at the
RF gun.

BT
end
2021/2/19 3:16:35

1st: 2.0nC
2nd: 1.6nC
at BT end
9

Bunch charge history in 2020
Charge amount at the sources became higher.
The transmittance is going to improve in 2021a.

e+
capturesectionend ofsector2
end of
LINAC

M. Satoh

RFgun

BT

BT

•
•
•

Increased Loss in 16_5→28_4
Once beams for PF, AR are tuned and their operations start,
it is difficult to tune the KBP beam, due to the interference.
Some pulsed steering magnets are added now.

N.Iida BPAC, 1.Mar.2021

The charge at BT end had been made lower
by requirement from HER.
10

Positron yield for 2021a
FC current (2021/2/13) was raised to 11.3 kA.
During winter maintenance, power supply andits surroundings were modified for noise
suppression.

Y. Enomoto
N.Iida BPAC, 1.Mar.2021

11

Positron bunch charge
Miyahara simulation yield (0.58)
Primary ee+/e-

Efficiency of e+ production

First BPM after target
Before LTR
RTL直後

Linac end

2020/10/21 (2020c)(one bunch operation)

N.Iida BPAC, 1.Mar.2021

2021/2/12 (2021a)(two bunch operation)

Y. Enomoto
12Measured emittance history at BT1
The e+ optics is very stable thanks to the DR.

The e- emittances have the minimum records at BT1.

Normalized
emittance X(gex)

Normalized
emittance X(gex)

OpticsMatching X(BMAGx)
Normalized
emittance Y(gey)

OpticsMatching X(BMAGx)Required value from LER is 30.

OpticsMatching Y(BMAGy)Normalized
emittance Y(gey)

OpticsMatching Y(BMAGy)Required emittance from the MR
N.Iida BPAC, 1.Mar.2021

BMAG=1 means the optics are matched to the design values.

13Summary of emittance explosion• Achieved charges at BT ends are;
• e-: 2.0nC(1st)+1.6nC(2nd)• e+: 2.6nC(1st)+2.2nC(2nd)• The measured emittances at the entrance of BT line (BT1)
are in the range of required values from the MR.

N.Iida BPAC, 1.Mar.2021

14

Emittance explosion in e- BT line

N.Iida BPAC, 1.Mar.2021

15

Emittance explosion in BT
e- X

e+X

Measured by WS● Newest data by WS● Jitter emittance●Same emittance lineof BT2 as BT1
Dec/2

Required emittancefrom LER/HER

emittance of e+
・In BT2, gey is within therequired value.
e+Y

e- Y

Dec/22

N.Iida BPAC, 1.Mar.2021

emittance of e・Close to the required
value in BT1, but it isexploding in BT2.
・Both X and Y are large
・BT2 has no correlation
with BT1.
→ It may be blowup,
not16
as much as an explosion.

Measured emittances with OTR and WS in BT
T. Natsui, T. Mori

gex
(µm)
Requiredemittancefrom HER

gey(µm)

N.Iida BPAC, 1.Mar.2021

Horizontal emittance isstill a little bit large due to SR.

WS HV: 750->450mVOTR Quads used in q-scanare changed to upstream.
WS HV: 750mV(11/30)→350mV(12/2)

17

Measured emittance and b-mismatch(BMAG) in BT
T. Natsui, T. Mori

Required emittancefrom HERgex(µm)：ge with WS●：gex measured with OTR●：gey measured with OTR
●

BMAGx

BMAGy

N.Iida BPAC, 1.Mar.2021

QMD4E

gey
(µm)

WS HV: 750mV(11/30)→350mV(12/2)→400, 500mV(12/17)

18

Measured emittance and b-mismatch(BMAG) in BT
T. Natsui, T. Mori

Required emittancefrom HERgex(µm)：ge with WS●：gex measured with OTR●：gey measured with OTR
●

BMAGx

gey
(µm)

N.Iida BPAC, 1.Mar.2021

QMD4E

QCD4E

BMAGy

WS:
Only vertical Q-scan were done again.
Quad of Q-Scan used far from the WS.
( Fiber: Input voltage=500mV )( Old PMT: High voltage=950mV )19Measured emittance and b-mismatch(BMAG) in BT
T. Mori, F. Miyahara, T. Natsui,
H. Ikeda, T. Mitsuhashi,
R. Yang
Required emittancefrom HERgex(µm)：ge with WS●：gex measured with OTR●：gey measured with OTR● ：ge with SRM+gatedcamera
●

BMAGx

gey
(µm)
QMD4E

●

SRM
at D4

N.Iida BPAC, 1.Mar.2021

QCD4E

BMAGy

●

→ It may be blowup,
not as much as an
explosion.

20Summary of emittance explosion( unsolved yet )• The measured emittances at the entrance of BT line (BT1)
are in the range of required values from the MR.
However,• the explosion of measured emittances of e- at the end of BT(BT2) has become weaker.
• Three vertical emittance measurements were done.
• Q-scan with OTRs
• Q-scan with a wire scanner• SRM+Gated camera• They are consistent to each other.

• The origin of the emittance blowup must be resolved as soon as
possible.
N.Iida BPAC, 1.Mar.2021

21

Injection efficiency• What should we do next ?
• Does the injection orbit
match to the HER ?
• The orbits at the BT end
were corrected.

Always the loss signal here is high.
And residual radiation is high here andaround the collimator D09V1.
N.Iida BPAC, 1.Mar.2021

22

HER Injection• The beam shutter mode at the end of BT has been available from 2020c.
• It is very powerful to study the BT end.
• Emittance measurements etc.

BS modeBT endDump mode

It had been difficult to study
downstream the Dump
WS, OTR

N.Iida BPAC, 1.Mar.2021

23

Orbit correction at the BT end
QuadBPM and Orbit tuning

Applied resultsof Quad BPM at
the end of BT.
pink → blue

Horizontal
orbit wascorrected.
→ blue+ny changed
einj~50→60%

Vertical orbit
wascorrected→ blueeinj~40→50%

N.Iida BPAC, 1.Mar.2021

24

HER injection -Horizontal• Horizontal emittance• The aperture for the injection is 5x10-7 m, corresponding to 4.4 mm at
D09H1(bx=39.7m).
• The collimator(D09H1) was not closed very much(18mm to 11mm, farfrom 4.4mm) when optics changing by*=8mm to 1mm, however the
beam was lost with optics change.
• It is considered that the problem is mainly from the vertical emittanceor/and orbit.

by*=8mm
D09H1: -18mm
N.Iida BPAC, 1.Mar.2021

by*=1mm
D09H1: -11mm
25

1-shot injection
The charges of injection beam were monitored by Turn-by-turn BPM with 1-shot injection

Y. Ohnishi# of Turn

PMD09H1
MQEAE18

MQEAE20
MQD3E16MQEAE22
PMD09V1

MQD3E18

downstream of
Septum MQI4E

MQEAE23

e-

MQI6E

1st
MQI5E
MQI4E
Calibration
is bad.

2nd
3rd

MQEAE23

4th~60% injection
1000 turns
e- beamN.Iida BPAC, 1.Mar.2021

HER_2020_12_14_18_39_17.data

The injected beam losses at Collimator D09V1
for every 2 turn due to the half integer vertical tune

26

HER injection ‒Vertical• Vertical emittance• D09V1: -1.66mm, DY(the vertical orbit of beam)=-0.2mm• → Distance between the center of beam and the D09V1 head(A) is -1.46mm• by=15.5m → ey=A2/by(1.46x10-3)2/15.5=1.38x10-7m, gey=1.9mm• Assuming 3sy, more than gey= 1.9mm/9=210µm beam will loss here.
• Since the measured vertical emittance is about 130µm, if the beam
passes the design vertical orbit, the injection beam should not be lost.

by*=8mmby*=1mm, D09V1: -1.66mm
N.Iida BPAC, 1.Mar.2021

27

The vertical orbit in the injection region
BT

lin

e

T. OkiQMD8E(BT)QMD8E(BT)
VM27E

VM28E
QMD10E(BT)QMF9E(BT)Step

QI4E(MR)outside the MR(m)

It is considered that the angle between the
BT line and the MR comes from the Geoid.
~80µm.

N.Iida BPAC, 1.Mar.2021

The photo was takenfrom the inside of thering, so thearrangement of theelectromagnets wasreversed.

28

The vertical bump in HER along to the injected beam

Injection point

A vertical bump orbit of the accumulated beam wasmade at the injection point so that the accumulated
beam would follow the injection beam.
The injection efficiency reached ~80%
at by*=2mm !
N.Iida BPAC, 1.Mar.2021

29

Injection efficiency of low emittance beam
The low emittance beam was made by artificially by cut with collimators in the BT.
M. Kikuchi

N.Iida BPAC, 1.Mar.2021

The injection efficiency increased from 50% to 70% at the time.
The lower emittance increases the injection rate to some extent.
But it didn't reach 100%.
→ We want to try again with measurement of the vertical collimator offset.

30

Plan of improvements for injection
Effect to injection eff.[%]before December

Inj. eff. [%]40

V. orbit at BT end

+10

50

ny in HER, H. and V. orbit at BT end

+10

60

Vertical bump of HER at the injection region +15

75

Low emittance with collimator

+15

90

Optics matching at Arc-4 ?

+10 ?

100 ?
Very rough estimation

N.Iida BPAC, 1.Mar.2021

31

Summary of injection efficiency• One of the reason why a bad injection efficiency is from thevertical orbit mismatch between BT end and the verticalcollimator in HER.
• The injection efficiency was improved by correcting the orbit at
the BT end and choosing the tunes.
• The injected beam mainly losses at the vertical collimator, D09V1
and injection region, which are considered from the high residual
radiation around them.
• The charge losses at the D09V1 are also monitored by Turn-byturn-BPM(TbT-BPM).
• The vertical alignments between BT and MR have somediscrepancy due to a different coordinate system about a geoid.
N.Iida BPAC, 1.Mar.2021

32

2-bunch injection• Until 2020c, 2-bunch injection was successful only for HER.
• At the begining of 2021a, it has been succeeded also for
LER !

N.Iida BPAC, 1.Mar.2021

33

2-bunche+ injection
injection and BG

2020.8.6 summary meetinge- injection

Injection
efficiency

VXD diamonds(BG monitors)

No problem !
Initially, the BG was low and the injection
efficiency was good, but it rapidly became
difficult to enter.

The 2-bunch injection had
been done in 2020ab run.

14分
N.Iida BPAC, 1.Mar.2021

34

2-bunch injection to LER
24/Jun/2020, 2-bunch injection failed….

19/Feb/2021, 2-bunch injection succeeded !
Total Current
Rep. Rate

Injection rate
were getting lower.

Charge 1stCharge 2nd

Injection rate
became high.

Inj. Rate
Inj. Eff
ECL BW

BGs were getting larger

Duration
BGs were stable as much as 1-bunch injection.
Diamond
VXD FW225
VXD FW135

N.Iida BPAC, 1.Mar.2021

35

Damping Ring (DR)QIF

2 bunch, FC on
Injection stopped
by I/L at DR

2 bunch, FC on
Continuous
injections can bedone by tuning RF
feedback system.
→See the next slide.

LTR
1 bunch,
FC on
RTL

QRF
The injection to the DR had been stopped
by the loss monitor near a RF cavity.
This interlock occurred when the FC works
and 2-bunch injection (The total current in
the DR was more than )N.Iida BPAC, 1.Mar.2021

36

Shift report: 2021_02_19_09
15:20 - DR operation with 2 bunch and FC on (T. Kobayashi, M. Nishiwaki, H. Ikeda)
Observation of RF behavior(response of RF voltage and cavity phase to beam)->Tuning of LLRF feedback loop
before tuning(DAC-IIR Filter OFF)amplitude

after tuning(IIR(BW 5kHz) ON)

phase

0.65%
50ms

"Inhibit injection" by the loss monitor seems cured by this tuning.
More detail investigation about the instability will be done.
37
N.IidaBPAC, 1.Mar.2021

Summary of 2-bunch injection• HER• The 2-bunch injection had been done in 2020ab.
• It had not been done in 2020c because the pulse width of the RF was
made narrower than the optimum value, 1 µsec due to the often klystrondown.
• In 2021a, the pulse width will be wider than 0.95µsec under the lower Es
voltage of the klystron, for stability.

• LER• The 2-bunch injection had not been able to done until 2020c.
• An instability in the longitudinal plane was occurred, which was improvedby tuning the RF feedback.
• It is considered that the reason why enable to the LER with 2-bunch was
due to the unstable beam from the DR.
• Now the 2-bunch injection to the LER is on going without any trouble.
N.Iida BPAC, 1.Mar.2021

38

Collaboration with Belle II for an injection• BT-PS file control system (See the next slide)• Matsuoka-san suggested that Hara-sanʼs group helps the file savesystem for the PS of BT.

• Injection support team
• Funakoshi-san made a special support team for the injection.
• The team aims to make an injection manual for the operators.
• At first, H. Nakayama, K. Nakamura, S. Tanaka, and I. Adachi joined it.
• They will help making an injection manual to take care of the
background monitors of Belle II.
• Of course, we welcome to join the injection tuning, or making theinjection beam.
N.Iida BPAC, 1.Mar.2021

39

BTe Orbit

At the end of 2020b, I saved the setting of a backleg at
the BE end changed for a measurement of WS for astudy, and accidentally loaded the file at the beginningof 2020c.
I am VERY sorry.
Future plan：• Be careful of File Save and Load
• Save GOLD Orbit at the time of injection.
• Display GOLD Orbit.
• Belle II people help us for the PS control system.
2020c(2020.10.30)

2020b(2020.6.25)
Good orbit

N.Iida BPAC, 1.Mar.2021

Backleg(HM171E)
had been modified forthe study just before thesummer shut down.

Bad orbit

40

Summary
LER

HER

Injection efficiency at by*=1mm

Usually more than 80%, but inthe end of 2020c, it became
lower because of LER optics
changing.

Raised up to 60% from 40% bycorrecting the BT end orbit in2020c.

Injection efficiency at by*=2mm

80~90%Up to 80% in 26/Feb/2021a !

Charge [nC] (1st + 2nd )2.6+2.2

2.0+1.6(gex, gey) at BT2 [µm]200, 30

300, 100

Required emittance [µm]150, 30

100, 40

2-bunch injection

Ready

Ready

Collaboration with Belle II for
Injection

N.Iida BPAC, 1.Mar.2021• PS control system of BT line
• Injection support team41