July 5, 2021

Status Of SuperKEKB
2021abFebruary 16 - July 5, 2021
Y. Ohnishi

Revised: July 9

Overview of Machine Performance

Keeping performance

Improvement of performance

Many effort is devoted to keep performance.
stability of machine, aging of devices and infrastructures2

2021ab Operation Summary<latexit sha1_base64="i8hb80pv1bomaFNfz46vRn7qm/Y=">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</latexit>⇤
y = 2 mm

D01V1 headreplacement<latexit sha1_base64="AHmtJdXLvtZjKQ9UQoYTW8HTTpY=">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</latexit>⇤
y = 1 mm

D02V1 headreplacement

HER BxB FB noise is fixed.
NIM bin and fanout replacement• The 2021a run started on 16th February andoperated for 140 days (4 months and half).

• The first ten days were devoted to the vacuum

940 mAscrubbing.

• We operated with βy* = 2 mm to checkhardwares and to test high current operation
safely.

1000 mA

Lp 3.12x1034

HER many aborts
BxB FB noise• Calibrations of BPM and collimator head

positions, etc. were also performed by using
beams during the first two weeks.

• D01V1(HER) head was replaced. The top jaw

was short for the LER collimator head (March 23).

• We squeezed βy* down to 1 mm on 10th

March. Beam currents increased with "bakingrun". 1000 mA / 940 mA w/o physics run• HER many aborts from April 20 to May 3.
• D02V1(LER) head was replaced due damage(June 7).

3

Peak Luminosity : 3.12 x 1034 cm-2s-1

Shift
D08_H05
pressure riseDay

7 daysMay 14 - 20

30 dayspeak luminosity !

May 18 - June 23

2021ab140 daysint. Lrecorded

int. Ldelivered747.2 pb-1

787.6 pb-1

May 18 swing

June 22 swing

1.964 fb-1

2.233 fb-1

May 18May 22

12.141 fb-1

13.482 fb-1

42.319 fb-1

47.370 fb-1

123.2 fb-1

138.6 fb-1
* online data4

Machine Parameters
2020b : June 21, 2020

2021b : June 22, 2021

Ring

LER

HER

LER

HER

Emittance

4.0

4.6

4.0

4.6

nm

Beam Current

712

607

790

687

mA

978

Number of bunches

Unit

1174

Bunch current

0.728

0.621

0.673

0.585

mA

Lifetime

760

1270

540

1320

sec

Horizontal size σx*

17.9

16.6

17.9

16.6

μm

Vertical cap sigma Σy*

0.403

0.324

μm*1

Vertical size σy*

0.285

0.229

μm*2

Betatron tunes νx / νy45.523 / 43.581 44.531 / 41.577 44.524 / 46.596 45.532 / 43.581

βx* / βy*80 / 1.0

60 / 1.0

80 / 1.0

60 / 1.0

Piwinski angle

10.7

12.7

10.7

12.7

Crab Waist Ratio

80

40

80

40

Beam-Beam parameter ξy

0.039

0.026

0.046

0.030

mm
%

Specific luminosity

5.43 x 1031

6.76 x 1031

cm-2s-1/mA2

Luminosity

2.40 x 1034

3.12 x 1034

cm-2s-15*1) estimated by luminosity with assuming design bunch length*2) divide *1 by √2

Vertical emittance (pm)nb : 393

Lsp

Lsp x1031 (cm-2s-1/mA2)

High Bunch Current Collision

LER

HER

IHER/ILER (ILER = 340 mA)

Vertical emittance (HER)

Vertical emittance (LER)

beam-beam
limit ?
Horizontal emittance (LER)<latexit sha1_base64="8mGvqa1xZ0pqSVJrwWQSI4iU0s4=">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</latexit>• We observed large beam-beam blowup in the LER. (40 pm w/o collision)• It depends on the HER beam current.
• Horizontal emittance also increases.
We consider coherent beam-beam head-tail instability and/or dynamic
beta/emittance effect.
6

re N ⌥⇠y± =2⇡ ± x z

s

y±

"y⌥

1.2 x1034 cm-2s-1 at 0.57 mA2 (393 bunches)
4.78 x 1034 cm-2s-1 is expected for 1565 bunches.
(ILER : 1.4 A / IHER : 1.0 A)

Beam-Beam Parameter ξy2021b HBCC

LER

HER
ξy+ : 0.0392 / ξy- : 0.0319

Bunch Current Ib (mA)

Lsp =<latexit sha1_base64="dwIf/5wVA3Bi4qhnRGqDLQeU/9A=">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</latexit>⇤
2ere y±
L
⇠y± =
± I±

L
nb Ib+ Ib⇠y± = ⇠y± (Ib⌥ )<latexit sha1_base64="9gmFbBwaoQxitAP1ZtFoGPYrL/8=">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</latexit><latexit sha1_base64="R/f84uPHPF8Q3b1QYuK+4UI7i9s=">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</latexit>• The beam current ratio is kept to be ILER : I HER = 5 : 4 (circle)• Beam-beam limit was observed at around 0.03 for HER.
• The bunch current ratio can be optimized to improve luminosity.
• The optimized ratio of beam current is 10 : 7 (triangle) at Ib+ > 0.8• Specific luminosity for βy* = 2 mm reproduces that of 2019 ab.
• Specific luminosity for βy* = 1 mm is improved compared tothat of 2020ab.
• Bunch current product is achieved larger than 0.5 mA2.

mA.

7

History of Specific Luminosity

HER BxB feedback gain (vertical)
decreased. Swing shift on May 9
HER many aborts(noise affects BxB FB)

D02V1 collimator
head replacement

2021abHER
1st off-resonancechange νy(-60 MeV)

2nd off-resonance(-60 MeV)(43.572 → 43.578)

0.45 - 0.50 mA2
0.40 - 0.45 mA2
0.35 - 0.40 mA2
0.30 - 0.35 mA2
0.25 - 0.30 mA2
0.20 - 0.25 mA2< 0.20 mA28

More detail of Lsp
HERchange νy43.572 → 43.578

HER BxB Feedback gain (vertical) decreased.
Swing shift on May 9
off-resonance (-60 MeV)

3.12x1034

Linac energy FB
trouble9maintenanceProjection of Specific Luminosity

max of nbIb+Ib- is 540 mA2(840 mA/818 mA, 1272)
target of 2021b LER / HER : 1.1 A / 1.0 A
700 mA2
nb = 1565

10

Beam Aborts and QCS Quench

11

LER and HER Abnormal Beam Abort
835 mA

H. Nakayama
typical samples• No orbit oscillation• Very fast beam loss withina few turns

12709 mABeam Abort due to Injection Beam
835 mA (1272 bunches)

kicker leakage orbit

Injected beam was lost partially.

Orbit in beam transport line
Energy deviation was large.

H. Nakayama
H. Kaji
13

QCS Quench List (except for earthquake and PS trouble)

4/19 (MO) Owl

5/10 (MO) Day

5/14 (FR) Owl

5/23 (SU) Owl

5/28 (FR) Owl

1:07

14:26

0:35

8:24

3:21

14

HER QC1LE

LER: 836 mA / HER: 819 mA
HER D09V1 damaged

LER QC1LP, QC1RP

LER: 906 mA / HER: 726 mALER D02V1 damaged

LER QC1RP

LER: 837 mA / HER: 679 mA
LER kicker trouble

LER QC1LP, QC1RP

LER: 836 mA / HER: 678 mA
LER D06V1 damaged

LER QC1RP

LER: 834 mA / HER: 677 mALER D06V1 damaged

6/2 (WE) Swing

20:13

LER QC1LP, QC1RP

LER: 840 mA / HER: 678 mA
LER D02V1 damaged

6/6 (SU) Day

16:06

LER QC1LP, QC1RP

LER: 838 mA / HER: 677 mA

LER D02V1 Collimator Damage and Replacement
Vertical collimator: D02V1 (LER)
tantalum (Ta) head with 10 mm long tip

beam

TOP

82.5 m upper stream of IP

beam
BOTTOM

June 8, 2021
15

S. Terui
T. Ishibashi
Y. Suetsugu

Improvements and Issues of Machine Performance16

Improvement of Continuous Closed orbit Correction (CCC) We modified the algorithm of orbit correction.
HER

HER

2020c

2021b

Momentum deviation is almost constant.
(No data here)

Sum of horizontal kicks in the arcs is kept to be constant.

Constrain of sum of horizontal kicks
was not sufficient.

17

Improvement of Continuous Closed orbit Correction (CCC) We modified the algorithm of orbit correction.
LER

LER

2020c

2021b

Momentum deviation is almost constant.

(No data here)

Sum of horizontal kicks in the arcs is kept to be constant.

Constrain of sum of horizontal kicks
was not sufficient.

This includes the QCS corrector (LER only).

18

IP X-Y/Dispersion Knobs

LER / HER

IP Chromatic X-Y Coupling Knobs

LER: R2* and R1*(QC1s)IP knob is separated for X-Y coupling and chromatic knobs.
(new knobs)
A. Morita
R1* and R2* are almost fixed to optimize luminosity.
R3* and R4* affect beam background.

• Sextupole magnet mounted on rotating table is utilized

19

since March 11 to suppress IP chromatic X-Y (model).
• Corrector strength and/or BG sometime limits the knob.
• Reduction of B-B blowup is not clear so far.

Chromatic X-Y couplings using TBT BPMs

LER
r1

r2

0.2
0.15
0.1

0.01
0.005

0

0

− 0.05− 0.005− 0.1− 0.01− 0.15− 0.002− 0.001

0

0.001

0.002

− 0.02− 0.002

0.02
0.015

0.1
0.01
0.05

0.005

0

0
− 0.005− 0.05− 0.01− 0.1− 0.015− 0.001

00.001− 0.02

− 0.2

0.002

r2

− 0.001

00.001− 0.025− 0.001

0

dp

dp

dp

r3

r4

r3

r4

r3

2.5

r4

0.08
0.06

1

0.5

− 0.001

r1

0.15− 0.150.1− 0.002

0.025

dp

1.5

0

Ohmi-san's criterion
r1' < ±12r2' < ±3 m

− 0.015

2.5

2

r2

0

0.001

0.002

1.5
1

0.02

0.5

0

0

− 0.02− 0.5− 0.04−1− 0.06− 1.5− 0.08−2− 0.002− 0.001

dp

0

0.001

0.2

0.001

r4

0.1

0

− 0.1

− 0.2

− 2.5

0.002

0.3

r3

2

0.04

− 0.1

G. Mitsuka

r2

0.2

0.015

0.05

− 0.2

r1

0.02

r1

HER

− 0.001

dp

0

0.001

− 0.3

− 0.001dp

IP chromatic knob on

0

0.001

dp

IP chromatic knob on

r1-6.034E-02-7.7644.012E+03

r2-6.763E-03-1.254-8.22E+01

r3

1.318

214.6

-6.755E+04

r4-2.319E-02

45.24

6.998E+03

+0.08
-0.1
+13

r1

1.69E-02-1.644-5.91E+03

r2

1.317E-02

2.028-2.022E+03

r3-2.772E-01

733.0-2.082E+05

r4-1.637E-01

26.81

1.044E+04

IP chromatic knob off

IP chromatic knob off

r1-4.634E-02-4.379

1.91E+03

r1-2.095E-02-25.991.256E+04

r2-9.726E-03-2.0792.188E+02

r2

1.2E-02-0.4769-4.409E+02

r3

1.678

185.0

-1.746E+04

r3-5.715E-01

652.4-7.325E+04

r4

9.563E-03

37.54

6.274E+03

r4-1.142E-01

24.53-3.876E+03

20

+0.03
+50
+5

LER

nb:1174

Beam Lifetime and Vertical EmittanceHER

current

1174

nb:1174

ver. emittance
60 pm

nb:393
nb:39322 pm

collision

45 pm

25 pm

single beamcollision

single beamεy depends on bunch current.

Lifetime
30 min

8 min
7 min

6 min
21

26 min

HER

βx*

80 mm

60 mm

βy*

1 mm

1 mm

I

800 mA

650 mA

nb

1174

1174

Ib

0.681 mA

0.545 mAεycollision

60 pm

45 pm

εy
single

25 pm

40 pm

life
collision

8 min

30 minlife
single6 min

32 min

40 pm

28 pm

1174

LER

32 mine+inj: 2 nC x 2 x 12.5 Hz x 80 %Imax= 1.9 A for lifetime: 8 min(TMCI limit : 1.4 A with nb:1565)

LER : CW 80 %Tracking Simulation
No Machine Error

LER : CW 0 %single beam

800 mA / nb:1174

single beam

800 mA / nb:1174

no collimators

εy = 25 pm

no collimators

εy = 25 pm

7.55 minsingle beamwith collimators

800 mA / nb:1174
εy = 25 pm

26.3 minsingle beamwith collimators

800 mA / nb:1174
εy = 25 pm

Touschek lifetime
is similar to CW 80%
with collimators.

11.2 min7.45 minThe simulation is consistent
with the measured lifetime
for CW 80 %.
22

HER : CW 40 %Tracking Simulation
No Machine Error

HER : CW 0 %single beam

650 mA / nb:1174

single beam

650 mA / nb:1174

no collimators

εy = 40 pm

no collimators

εy = 40 pm

57.7 minsingle beamwith collimators

650 mA / nb:1174
εy = 40 pm

67 minsingle beamwith collimators

650 mA / nb:1174
εy = 40 pm

Touschek lifetime
is similar to CW 40%
with collimators.

46.6 min46.5 minThe simulation is longer
than the measured lifetime
for CW 40 %.
46 min > 32 min
23

Lifetime and Vertical EmittanceLER
The εy is 22 pm - 25 pm for the single beam.
The εy increases up to 60 pm due to beam-beam blowup at 800 mA(0.68 mA/bunch).
The luminosity reduction is 65 %.
The DA can almost explain the measured lifetime.
The crab waist reduces the DA. But the tight collimators reduce the PA significantly. The collimators make small
difference between CW 0 % and CW 80 %.
The lifetime is about 8 min for collision at 800 mA. It is quit shorter than what we expected.
HER
The εy is 28 - 40 pm which depends on the bunch current.
Beam-beam blowup is mild. It is from 40 pm to 45 pm at 650 mA(0.55 mA/bunch).
The collimators reduce the DA significantly. It is same as the LER
The measured lifetime is shorter than the simulation. (32 min < 46 min; vacuum lifetime not included )24

LER Collimator ImpedanceTransverse Mode Coupling Instability (TMCI)
Kick factor (vertical) depends on D02V1, D03V1, D06V2, D06V1.

Σ βy κ = 36 (V/pC) on June 30

P<latexit sha1_base64="PD1zxbHULJ0mlj+w4Afvsl8Gn/A=">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</latexit>

T0 Ith i yi i⌫s⌫y,th =
=
4⇡E/e
2
⌫s
fs =
fs = 2.3325 (kHz)*T0

LER Vertical Emittance (pm)collimatoropened (test)

vertical tune shift : -0.013 (1/mA)
LER Vertical Tune

LER Bunch Current (mA)sum of βy x kick factor ( V/pC)

CGLOPT:SUM:BETA_KICK:V

2⇡fs (E/e)
Ith = P= 1.6 mA > 0.9 mA (measured)i yi i<latexit sha1_base64="zlcCAqAw4QZg1HmbxXyeNi9mRG0=">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</latexit>

The theoretical threshold is factor of 1.8 to the measured threshold.
The measured kick factor is 1.8 times larger than the GdfidL simulator.

* measured value (M. Tobiyama)25

Calculation of GdfidL Electromagnetic Field Simulator

T. Ishibashi

Length(along beam axis) of head : 10 mm

1 (V/pC/m)

Zagorodnovʼs equationk⊥ = 0.215AZ0c

α
σzd 3

[I. Zagorodnov, Wakeﬁeld Calculations for 3D Collimators,
EUROTeV-Report-2006-074.]

26

BxB Feedback Noise in HER

May 6
HER BxB FB noise is fixed on June 30.
NIM bin and fanout replacement

D02V1 replacement
and maintenanceMay 3<latexit sha1_base64="cquYpzb5FH74wQbaf0kcTkUt7F4=">AAACenichVHLSsNAFD2Nr1pfVREEN2JRFKHciKC4Krhxqa1VQSUkcapD0yQkaaGG/oA/4MKVgoj2M9z4Ay76CeJSwY0Lb9OAqKh3mJkzZ+65c2bGcC3pB0SthNLV3dPbl+xPDQwODY+kR8d2fKfqmaJoOpbj7Rm6Lyxpi2IgA0vsuZ7QK4Yldo3yent/tyY8Xzr2dlB3xWFFP7ZlSZp6wJSWnjgoeboZlrTQdqQvGo1wW6OGls5QlqKY/gnUGGQQx6aTvsEBjuDARBUVCNgIGFvQ4XPbhwqCy9whQuY8RjLaF2ggxdoqZwnO0Jkt83jMq/2YtXndrulHapNPsbh7rJzGLD3SLb3QAzXpid5/rRVGNdpe6jwbHa1wtZGzycLbv6oKzwFOPlV/eg5QwmrkVbJ3N2LatzA7+trp+UthLT8bztEVPbP/S2rRPd/Arr2a11sif4EUf4D6/bl/gp2lrEpZdWs5k8vFX5HEFGYwz++9ghw2sIkinxviEndoJt6VGWVBWeykKolYM44voSx/AB50kx0=</latexit>

operation tune

fnoiseT0

IGPF:HERDV:SRAM:PEAKFREQ2

M. Tobiyama

The noise moved away from the working point on May 14.
27

Tune History: Optics degradation

QCS
initialization

1

maintenance
no QCS initialization

1. 3/28 Magnet PS QC1LE Charging Volt I/L Trouble
2. 4/19 QC1LE quench(4/21 On -> Off-resonance)

2

H. Koiso

3

4

5

6

7

3. 4/26 Off -> On-resonance
4. 5/10 QC1RP & QC1LP quench
5. 5/12 Maintenance
6. 5/14 QC1RP quench
7. 5/23 QC1RP & QC1LP quench

Discrepancy between model and measurement of νy increases rapidly after QCS initialization with optics corrections.
When we skip the QCS initialization, the discrepancy becomes small. QCS coils move slowly or field/orbit drifting ?

28

Injector Linac, Beam Transport, Injection System

29

Injector Linac

M. Satoh

60 klystron units
240 accelerating structures (S-band 2-m-long)
Bunch charge (nC) in the current nominal operation

8 Sectors (A-C,1-5)

Energy Knob

J-ARC
1.5 GeV

B
C

Thermionic gun

1.1 GeV e+
Damping Ring

PhotocathodeRF gunAe+e+ capture section
target

ECS

3

e-

C

1

4

2.5

5

Energy Knob

Acceleration

ECS

PF-AR

Deceleration
Acceleration
3

HER

LER 4 GeV e+

1.1 GeV2

PF

HER 7GeV
PF-AR 6.5 or 5 GeVStand-bye+

0.1 - 0.3

LER

chicane

4.2 GeV

1.5 GeVLER
PF/PF-AR2e+ target

1-2
10 e- for e+ production

BCS

1

HER

4

PF 2.5 GeV

5Masanori Satoh Beam energy for each beam mode along the beam line after the J-ARC.

30

Bunch Charge from Injector Linac

QE decreased due to human error (end of March)
Bunch charge feedback was stopped
because laser power reached 100 %.
1st bunch

Positron charge at BT end

Electron charge at BT end

2nd bunch

Bunch charge reduces.

Charge (nC)

Charge (nC)

Charge FB

Laser mirror
was adjusted.
QMD13P_K

QMD10E_M

Average charge is ~ 1.2 nC/bunch
Stability of charge is poor.
2-bunch injection is not available so far because
the emittance of 2nd bunch is larger than 1st bunch.

Average charge is ~ 2.4 nC/bunch for 1st bunch
2nd bunch is lower than 1st bunch.
31

Injection and emittanceβy* = 2 mm

LER

N. Iidaβy* = 2 mm

HER

32

N. Iida

Issues of injection• HER• The injection efficiency(“raw”) is insufficient. It is 40~60%.
• The blowup of emittances in the e- BT line is still serious issue.
• The normalized emittance(γεx,y) blows up from 20 μm in BT1 to 100~200μm in BT2.
• Injection efficiency can not be kept without tuning of the horizontal orbit at the injection point.
• Septum angle and position have to change.
• After an abort, the septum angle has to reduce 2x10-4 rad and it should be resumed at thefull current.
• Bunch charge of e- beam is getting lower from 1.4nC to 1.0nC during short term.The 2-bunchinjection is not available.
• The emittances of the 2nd beam become larger than 1st bunch after the positron target.

• LER• The injection efficiency and beam backgrounds for the 2nd bunch are worse than 1st bunch.
332021.06.30 16:48

Harmonic number = 5012

Hor. amp. (ADC)

LER: 600 mA (1565 bunches)
0.383 mA/bunch

injected + stored
bunch (1-bunch)

Data of Bunch Oscillation Recorder (BOR)
Large orbit leakage due to injection kickers is observedin the horizontal plane after injection in the LER.
Problem is that pulse shapes (half sine) are different
among six kickers.

kickerleakage orbit

2 μsecβx = 23.3 (m) at BOR

abort
gap

bunch idThis might be beam loss (BG) at higher beam current andsource of instabilities.

abort
gap

QC2LP (O) : radius = 30 mm
βx = 163 m. Δx= 9.5 mm

xn+1 (mm)Δx (mm)2Jx = 5.56 x 10-7 m# turnsxn (mm)34

sample-1

sample-2

Data of Injection Beam using TBT BPMs in LERβx =24.42 m

Horizontal injection error:

Kicker leakage orbit (stored beam):

2Jx = 1.47x10-6 m

2Jx = 5.56 x 10-7 m

QC2LP (O) : radius = 30 mm
βx = 163 m. Δx= 15.5 mm

QC2LP (O) : radius = 30 mm
βx = 163 m. Δx= 9.5 mm

D06V1 : half width = 6 mm
βx = 14.6 m. Δx= 4.6 mm

D06V1 : half width = 6 mm
βx = 14.6 m. Δx= 2.9 mm

sample-3

βx =24.42 m

1/3 of injection error

Oscillation is damped in 250 turns
owing to BxB feed back system.

35

Summary of Machine Operation

36

Achievement of 2021ab

Summary of Machine Operation
1. Difficulties of increasing beam currents
Abnormal beam abort with beam loss; no oscillation, very fast beam loss within a few turns. Damaged collimator headenhances the aborts (?).
Narrow collimator aperture (physical aperture: PA) which is smaller than dynamic aperture (DA)Short lifetime in the LER; Crab waist reduces DA. However, the aperture in the LER is PA = DA.
Lower "TMCI" threshold; 0.9 mA/bunch, large tune shift of single bunch ~0.013 > half of synchrotron tune in the LER
Injection kicker leakage orbit in the LER; It becomes a source of instabilities. Beam loss is proportional to stored beam
current. We measured the beam loss owing to orbit oscillation using BOR.
BxB FB in the HER; noise effect (fixed) and feedback gain, feedback gain and luminosity.
Synchro-beta resonance structure; good working area is small. Luminosity and DA is compatible ?
Stabilities of linac injector; Many types of feedback system should work sufficiently. Stability of injection system; septum
and kickers, especially HER septum behavior.
2. Beam-beam blowup
Effect of chromatic X-Y couplings is still unclear or IP knob is not sufficient. Rotating sextupoles in LER is effective.
Beam current ratio between LER and HER affects flip-flop of beam size.
3. Beta squeezing (not performed in 2021ab)
Down to 0.8 - 0.6 mm is necessary to improve luminosity. Training process is needed. (It takes time; see βy* = 1 mm)
38

Near-Term Plan

2021b

2021c

2022b

TargetAchieved

TargetTargetLp (cm-2s-1)

3.8 x1034

3.12 x1034

4.8 x1034

8 x1034

int. L (fb-1)

280

213.5

410

730

Imax (A)

1.1

1.0 (0.85)

1.2

1.6

39

Y. Suetsugu

Works Planed in This Summer Shutdown• Regular maintenance• Movable Collimator• Replacement of 2 collimator heads in HER• Upgrade of driving device of 2 collimators in HER• Replacement of collimator head (D06V2) with hybrid-type (tantalum and Cu coated carbon)
in LER• Relocation of D02V1 in LER (not decided)• Exchange of the mirror of SR beam size monitor in LER• Installation of HOM absorber at RF section (Nikko) in HER• Beam transport line (BT)• beam profile monitors with OTR screen• beam shutter at the injection in LER• Installation of strip-line kicker in RTL line (DR)• Infrastructures; measures against aging• Replacement of HV (66 kV and 6.6 kV) power cables• Repair of roof at power stations to avoid leakage rain drops• Replacement of old cooling water pumps
40

beam

Near-Term Plans at Injector Linac

K. Furukawa• Summer 2021
• Amplifier and optical elements to 2nd laser for rf-gun• Cathode and window replacement for rf-gun• Core switch upgrade for the computer network• Seven pulsed steering magnets in upstream linac• Solid state amplifiers to replace a mid-power klystron• Degraded rf waveguide replacements• Fast beam position monitor to separate e-/e+• 2nd rf-gun as a backup/development, … and more

Laser shaping with DOE

Secondary RF gun

New beam position monitor

Core network switches• Upgrade before 2026
• Pulsed magnets/fast kickers• Girder movers• Energy compression system• RF gun• Positron capturing• Accelerating structures• New capacitors to eliminate PCB

Pulsed magnets/kickers

High precision movers

RF gunPCB capacitor renewal

Positron capture section

New energy compressor

Accelerating structure41

εemittance(2.3 nC)〜99.7/3.2 µm (BT1)nx,nyPositron beam

M. Satoh• 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:

Goal: εnx,nxy (4 nC)〜100/15 (H/V) µｍ)

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 atdownstream e+ target)• Increase FC field and DC solenoid field. (power supply should be improved)

Design value (0.58)
Achieved

42

Luminosity Projection