SuperKEKB LS1 status
and
ARC report
Kyo Shibata(on behalf of SuperKEK Accelerator Group)2023.2.13
44th B2GM Plenary Session

Inter-University Research Institute Corporation High Energy Accelerator Research Organization (KEK)
大学共同利用機関法人 高エネルギー加速器研究機構 (KEK)Contents• LS1 status• Introduction• Challenges and countermeasures• LS1 schedule• IR status (Tsukuba straight section)• NLC status (Oho straight section)• Others• ARC report• Summary
13/Feb./2023

44th B2GM Plenary Session

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Contents• LS1 status• Introduction• Challenges and countermeasures• LS1 schedule• IR status (Tsukuba straight section)• NLC status (Oho straight section)• Others• ARC report• Summary
13/Feb./2023

44th B2GM Plenary Session

3Challenges as a luminosity frontier machine

Y. Suetsugu (2021.09.02)
The 25th KEKB Accelerator Review Committee+ 6) Low injection efficiency especially in HER.
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44th B2GM Plenary Session

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Countermeasures against challenges
Y. Suetsugu (2021.09.02)
The 25th KEKB Accelerator Review Committee

During LS1
Done before LS1
Under consideration(It was found that it is not easy.)

Under consideration
During LS1

Done before LS1
Under consideration
During LS1
During LS1 (Partially)
During LS1 (Partially)
During LS1 (Partially)

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44th B2GM Plenary Session

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Schedule
Ceiling aseismic reinforcing work

• LS1 : ∼15 months from July 2022 to autumn 2023

• 2022b run stopped earlier than planned due to high electricity costs (22nd June), but LS1 major
works began on 11th July as scheduled.
• Beam operation will restart from autumn 2023.

• Major works during LS1 other than accelerator upgrade:• Belle II maintenance and reinforcement••

Replacement of PXD and TOP MCP-PMTs, new IP beam pipes, and so on.
IR works are required, including QCS extraction & reinstallation, disassembly & reinstallation of magnets,
beam pipes, radiation shields, etc.

• Aseismic reinforcing work of the ceiling of the laboratory building (Oho Lab. & Fuji Lab.)••

It took about 5 months and it could be done only during long shutdown.
During this work, we could not use ceiling crane required for NLC construction at Oho Lab.!!

S. Nakamura

LS1 schedule

We are here now!!

2022

JFY2022

4

5

6

7

8

2023
9

10

2022b run
Ceiling aseismic reinforcing work

11

12

1

13/Feb./2023

4

5

6

7

8

3

Long Shutdown 1 (Accelerator upgrade)
Belle II maintenance & reinforcement2023

JFY20232

2024
9Long Shutdown 1 (Accelerator upgrade)
Belle II
maintenance & reinforcement
44th B2GM Plenary Session

10112023c run

12

1

2

3

2024a run6IR (Tsukuba straight section) #1
QCS movable platform

Belle II

• Major work items in accelerator tunnel:• Disassembly and reinstallation of concreteradiation shields• Belle II maintenance & reinforcement work
• Disassembly and reinstallation of magnets, beam
pipes for QCS work
• QCS extraction & reinstallation• QCSR cryostat leak test
• QCS cryostat modification

IR

QCS cryostat

Concrete radiation shield

We are here now!!

2022
5

6

JFY2022

7

8

2023
9

Concrete shield disassembly

2022b run

10

11

12

1

JFY2023

13/Feb./2023

5

Belle II work

6

7

8

QCS reinstallation
Magnet & beam pipe disassembly
Belle II
maintenance & reinforcement

2

3

QCS cryostat
modification

QCS extraction
QCSR cryostat leak test

Belle II maintenance & reinforcement

2023
4

PositronbeamElectronbeam

IR (Tsukuba straight section)
4

Tsukuba lab.

2024
9

10

11

12

1

2

3

Concrete shield reinstallation

Belle II work

44th B2GM Plenary Session

2023c run

2024a run7IR (Tsukuba straight section) #2
IR• Concrete radiation shields disassembly (already done)

Tsukuba lab.

• Concrete radiation shields were temporarily removed for IR works.
• They will be reinstalled in mid September 2023.
• To suppress background noise of Belle II, 2 concrete shields will be replaced with new ones.
• New shields will be delivered in March 2023.

Electronbeam

PositronbeamThis shield will be replaced with new one.
This space will befilled with concrete.

Concrete shield disassembly work
13/Feb./2023

New concrete shield
44th B2GM Plenary Session

H. Yamaoka
8IR (Tsukuba straight section) #3• Disassembly of magnets & beam pipes for QCS extraction (already done)IR

Tsukuba lab.

• To make space for QCS extraction, magnets and beam pipes were removed.
• For QCS cryostat work, some magnets and beam pipes on QCS movable platform
were also removed.
Magnets & beam pipes should be disassembled

QCS extraction

Positronbeam

QCS extraction

QCS movable platform
13/Feb./2023

QCS movable platform

Electronbeam

Disassembly work
44th B2GM Plenary Session9IR (Tsukuba straight section) #4
IR• QCS extraction (already done)

Tsukuba lab.

• RVC disassembly was performed by Belle II and SuperKEKB for the first time.
• RVC : Remote Vacuum Connection between IP bellows chambers and QCS beam pipes• DESY, who is RVC developer and has been in charge of RVC disassembly so far, also joined thework online. Thank you very much for the kind work manual and cooperation!!
• Although camera for monitoring the RVC movement did not work, disassembly work went well.

Electronbeam

Positronbeam• QCS extractions of both sides were completed successfully in one day!!
RVC lock flange of IP bellows chamber
K. Gadow (DESY)

RVC mechanism
13/Feb./2023

Remotemanipulation
wheel
44th B2GM Plenary Session

QCS extraction10

IR (Tsukuba straight section) #5
IR• QCSR cryostat leak test (already done)

Tsukuba lab.

• Pressure in QCSR cryostat has been higher than that in QCSL cryostat.

• Residual gas analysis showed that vacuum leak has occurred in QCSR cryostat.
• However, vacuum leak test before LS1 did not detect any vacuum leak.

• Thorough vacuum leak test was performed after QCS extraction.

Electronbeam• At last, the location of the vacuum leak was identified!!
• Vacuum leak will be stopped during LS1.

Positronbeam• Inside observation of beam pipes• Inside of IP bellows, QCS beam pipes were observed by fiberscope.

• Fiberscope observations showed that RF fingers of IP bellows and QCS beam
pipes are discolored but healthy.

QC1RP

Vacuum leak test of QCSR cryostat
13/Feb./2023

QC1LE
44th B2GM Plenary Session

IP bellows chamber with BPM
11

IR (Tsukuba straight section) #4
IR• Future works

Tsukuba lab.

• QCS cryostat modification• To reduce Belle II background noise, the material at the tip of QCS cryostat will be changed from
W to SUS.
• QCSR front cap replacement• QCSL front plate replacement• To make more space for Belle II cables, the tip of QCSR cryostat will be thinner.

Electronbeam

Positronbeam• QCSR cryostat modification including front cap replacement• QCS cryostats will be disassembled for these works.
BPM feedthroughBPM feedthrough• It is necessary to shift QCS beam pipes in longitudinal direction.
QCS beam pipe

QCS beam pipe

Y. ArimotoTo access QCS pipes & BPMs,
this part should be disassembled.

To access QCS pipes & BPMs,
these windows should be open.

T. OkiY. Arimoto
QCSR front plate
replacement

QCSL
13/Feb./2023

QCSR front cap
replacement
44th B2GM Plenary Session

QCSR
12

IR (Tsukuba straight section) #5
IR• Remaining works in accelerator tunnel:••••

Belle II maintenance & reinforcement (∼ June 2023, original schedule)
QCS cryostat modification (February ∼ March 2023)
QCS reinstallation (July ∼ August 2023)
Concrete shield reinstallation (Sep. 2023)• It is required to coordinate schedule with Belle II work and NLC construction.

IR (Tsukuba straight section)

We are here now!!

2022
5

6

JFY2022

7

8

2023
9

Concrete shield disassembly

2022b run

10

11

12

1

JFY2023

13/Feb./2023

5

Belle II work

6

7

8

QCS reinstallation
Magnet & beam pipe disassembly
Belle II
maintenance & reinforcement

2

3

QCS cryostat
modification

QCS extraction
QCSR cryostat leak test

Belle II maintenance & reinforcement

2023
4

PositronbeamElectronbeam• All works can be completed by the end of September 2023.

4

Tsukuba lab.

2024
9

10

11

12

1

2

3

Concrete shield reinstallation

Belle II work

44th B2GM Plenary Session

2023c run

2024a run13

Oho straight section #1
Concrete radiation shield• Major work items in accelerator tunnel:

D05 wiggler section

Tsukuba (Belle II)
Oho lab.

D04
D05

Positronbeam

S. Nakamura

Oho straight section (D05)

We are here now!!

2022
4

5

6

2022b run

JFY2022

7

8

2023
9

10

11

RF cavity
inspection
Crane not available
Ceiling aseismic reinforcing work

Concreteshield removal

12

1

JFY2023

5

6

7

8

3

RF cavity replacement

2024
9

10

11

12

1

2

3

NLC construction
New radiation shield
installation

13/Feb./2023

2

NLC construction

2023
4

Oho
straight section• Disassembly and reinstallation of concreteradiation shields• NLC construction (LER)• RF cavity replacement (LER)• Ceiling aseismic reinforcing work
• Installation of new radiation shields for NLC

Concrete shieldreinstallation

44th B2GM Plenary Session

2023c run

2024a run14

Oho straight section #2• Concrete radiation shields disassembly (already done)

Tsukuba (Belle II)• Concrete shields were placed outside Oho laboratory building.

• They will be reinstalled in September 2023.

Ohostraight section• Concrete radiation shields (6/12) were temporarily removed for NLC construction.
D04
D05

Positronbeam

Oho Lab.

Disassembled concrete shield

Concrete shield disassembly work
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Oho straight section #3
Tsukuba (Belle II)• Wiggler magnets and beam pipe removal (already done)••••

Double pole magnet (3 ton) : 20
Single pole magnet (2 ton) : 10
Half pole magnet (1.5 ton) : 20
Cables : 3 ton

D04
D05

• Removed beam pipe for wiggler magnet : 10 beam pipes• Disassembly procedure
•
•
•
•
•

Removal of wiggler magnet cables
Upper parts of wiggler magnets disassembly
Beam pipes removal
Upper parts of wiggler magnets reassembly
Wiggler magnets removal

Positronbeam

10 times

S. Nakamura

Wiggler beam pipe removal work
13/Feb./2023

44th B2GM Plenary SessionOhostraight section• Removed wiggler magnet and cable : 50 magnets and their cables

16Oho straight section #4
Magnet power supply room (ground level)• Future works for NLC construction

D04
D05

• Future works for radiation shielding enhancement• Production & installation of new Pb radiation shields• Production & installation of additional concrete shields• Reinstallation of concrete shields

Cable pit 1

Positronbeam

Cable pit 2
S. Nakamura

Additional concrete shields

collimator∼50 mmNew Pb radiation shield
Y. Sakaki
13/Feb./2023

concrete shields

44th B2GM Plenary SessionOhostraight section• Collimator relocation from D03V1• Q magnet relocation (done) and alignment• Skew sextuple magnets installation• Beam pipe installation• Installation of new power supplies• Magnet cabling works

Tsukuba (Belle II)

Cable pit (KEKB tunnel)
17Oho straight section #5
Tsukuba (Belle 2)• Remaining works in accelerator tunnel:

Oho lab.

D04
D05• All works can be completed by autumn 2023.

Positronbeam• Schedule is very tight.

Oho straight section (D05)

We are here now!!

2022
4

5

6

2022b run

JFY2022

7

8

2023
9

10

11

RF cavity
inspection
Crane not available
Ceiling aseismic reinforcing work

Concreteshield removal

12

1

JFY2023

5

6

7

8

3

RF cavity replacement

2024
9

10

11

12

1

2

3

NLC construction
New radiation shield
installation

13/Feb./2023

2

NLC construction

2023
4

Oho
straight section• NLC construction (∼ Sept. 2023)• RF cavity replacement (Jan. ∼ Feb. 2023)• New radiation shield installation (August ∼ Oct. 2023)• Concrete shield reinstallation (Sept. 2023)

Concrete shieldreinstallation

44th B2GM Plenary Session

2023c run

2024a run18

Other major works (excluding Linac)
T. Ishibashi• Robust collimator head (LER)• As countermeasure against kicker-pulser misfiring and resulting
destruction of collimator
•

MR

•
•
•

Carbon collimator head

Replacement with carbon head of horizontal collimator D06H3 and relocationfrom D06H1 to D06H4
Carbon head production : ∼ March 2023
Head replacement : Spring ∼ Summer 2023
Collimator relocation : Spring ∼ Summer 2023

• New beam pipes with wider aperture at HER injection point• For injection efficiency improvement••••

Y. Suetsugu

Beam pipe at
HER injection point

New beam pipes with wider aperture & New BPM for precise measurement of
injected beam
Beam pipe production : ∼ March 2023
Beam pipe replacement : Spring ∼ Summer 2023
Septum baking : ∼ Summer 2023?

• RF cavity modification and replacement (LER)• For stable operation with larger beam current

DR

•
•

Modification : Input coupler replacement, cooling power enhancement, coaxial
line modification, etc. (done)
Cavity replacement (D05A) : January ∼ February 2023

• Vacuum seal replacement at RF section (DR)• For pressure reduction•

Replacement from elastomer gasket to metal gasket for dummy pipes (done)• DR Extraction kicker power supply modification and repair (DR)• For stable operation

DR Ext. kicker
13/Feb./2023•

DR RF section

Modification : December 2022 ∼ August 2023

• And so on…
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Contents• LS1 status• Introduction• Challenges and countermeasures• LS1 schedule• IR status (Tsukuba straight section)• NLC status (Oho straight section)• Others• ARC report• Summary
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26th KEKB Accelerator Review Committee• 26th KEKB ARC meeting was held on 13-14 December 2022.
• Meeting was held in hybrid mode.
• 7 committee members : in person• Several others : on zoom

• 22 oral presentations were given by KEKB staff members.

• The slides of the presentations are available at https://www-kekb.kek.jp/MAC/2022/

KEKB ARC Committee members

Agenda of 26th KEKB ARC meetingFrank Zimmermann
Chair CERN
Ralph Assmann
DESY
Paolo Chiggiato
CERN
Paolo Craievich
PSI
John Fox
Stanford University
Andrew Hutton
JLab (excused)
In Soo Ko
POSTECH
Catia Milardi
INFN-LNF
Evgeny Perevedentsev BINP
Katsunobu Oide
UNIGE/CERN and KEK (ret.)
Qing Qin
ESRF
Bob Rimmer
JLabJohn Seeman
SLAC
Michael Sullivan
SLAC
Tom Taylor
CERN (ret.)
Rogelio Tomas
CERN
Tadashi Koseki
KEK, Director of Acc. Laboratory, Ex Officio Member
Makoto Tobiyama
KEK, Head of Acc. Division III, Ex Officio Member
Mika Masuzawa
KEK, Head of Acc. Division IV, Ex Officio Member
Hiroyasu Ego
KEK, Head of Acc. Division V, Ex Officio Member

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Executive Summary• Executive Summary

In summer 2022, SuperKEKB achieved a new world record luminosity of 4.7×1034 cm-2s-1,
which is a significant accomplishment, more than twice the previous KEKB record.
Among the various issues encountered were
(1) the interplay between a single bunch instability and the feedback system, which was
successfully solved by feedback tuning,(2) still unexplained sudden beam loss, which is tentatively attributed to “fireballs”,(3) large vertical equilibrium emittances in both rings,(4) emittance growth in the BT, and(5) poor or unstable injection conditions.
Many upgrade activities are underway in the current Long Shutdown (LS) 1. Beam
operation is expected to resume in October 2023.
The age profile of the SuperKEKB personnel is a concern. About a third of the team isrehired retired staff, which is largely outnumbering the staff below 40 years of age.
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Key Recommendations 1• Key Recommendations

The Committee has made recommendations throughout the different sections below. The mostsignificant of these recommendations and a few more general recommendations are summarizedhere:

1. The ARC committee recommends actively recruiting new young staff members to help withthe wide-ranging accelerator work of SuperKEKB and to prepare for the next decades ofoperation (R1.1).
2. Find a mechanism to engage additional PhD students (perhaps also already master students
and even undergraduates), from Japanese universities or from abroad in the exciting and realtime accelerator environment of SuperKEKB, in both experimental and theoretical acceleratorphysics studies (R1.2).
3. Develop a new algorithm to correct the orbit in a way that is insensitive to possible motion of
BPMs without capacitive sensors and their calibrations (R2.4).
4. Simulate the effect of the measured vertical floor deformation by up to 40 mm on the verticalemittance in the LER and HER (R11.1).
5. Consider realigning the whole ring, especially the Southern part (R11.2).
6. Simulate the injection efficiency to the LER, by changing the injection offset, which may affectthe efficiency or the lifetime for large amplitude particles (R9.6).
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Key Recommendations 2• Key Recommendations

7. Quantify the expected integrated luminosity improvements for all specifically proposed LS2
projects. Update annually (R21.2).
8. Investigate through a combination of electro-magnetic, mechanical and shower simulations(as performed for LHC collimators) whether a sudden collimator jaw deformation by ~100
micron could occur, triggered by HOM heating or small beam impact, which could then lead toa self-amplifying increasing deformation and catastrophic sudden beam loss (R17.5).
9. Given the ongoing extremely high concern for the cost of electrical power, study
configurations for the RF system in SuperKEKB that will allow for full or nearly full beam
operation while significantly lowering the cost of RF power generation (R12.2).
10. Complete a comprehensive study of the possible advantages coming from inserting an ECS in
the e- BT before proceeding with the real device construction (R8.2).
See “(C) Findings, Comments, Recommendations” for details.
1.
2.
3.
4.
5.

SuperKEKB Status 6. Monitor
2021c-2022b
7. Injector
Belle II Status
8. BT
MDI (GB)
9. Injection
Control
10. Vacuum

13/Feb./2023

11. MR Magnets & QCS
12. RF
13. Helium Refrigerator for SRF
14. Optics Issues
15. Collimator Issues
44th B2GM Plenary Session

16. Impedance Issues 21. LS2, IR Modifications
17. Sudden Beam Loss 22. Others. QCS Tour, etc.
18. NLC
19. ITF Summary
20. Beam-Beam24

Summary• Many upgrade works are done during Long Shutdown 1 (LS1).

• LS1 started in July 2022 and will end in autumn 2023. (∼15 months)• “Belle II maintenance & reinforcement” and “Aseismic reinforcing works of theceiling of the laboratory building” are also done during LS1.

• Status of “IR works” & “NLC construction” were reported in detail.

• Both works are progressing as planned so far.
• It is possible to complete all works by October 2023 and resume beam operationfrom autumn 2023.
• It takes much longer time for some materials and devices to be delivered, so more
careful coordination of LS1 schedule until the end of LS1 is required.

• 26th KEKB ARC meeting was held on 13-14 December 2022 in hybrid mode.
• ARC report and slides of the presentations are available athttps://www-kekb.kek.jp/MAC/2022/

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Fin.

Thank you for your attention.

Inter-University Research Institute Corporation High Energy Accelerator Research Organization (KEK)
大学共同利用機関法人 高エネルギー加速器研究機構 (KEK)Backup

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