Welcome and short summary of upgrade
work (LS1)Mika Masuzawa, Hiroyasu Ego, Makoto Tobiyama
KEK Accelerator Laboratory1

Emergency Assembly Area2

We are here(3-go-kan)

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The 27th KEKB Accelerator Review
 25/Mar/2024 – 27/Mar/2024
 https://superkekb.kek.jp/event/135/
 https://us02web.zoom.us/j/82433765439?pwd=Y0R3V2dpYTI2a2t5cnlvRXFTY2Ztdz09• Meeting ID 824 3376 5439
• Passcode 3300

 A. Hutton*, R. Rimmer, C. Milardi, F. Zimmermann, E. Perevedentsev*, J. Fox,J. Seeman, P. Craievich, M. Sullivan, P. Chiggiato, Q. Qin, R. Assmann, R. Tomas,T. Taylor, K. Oide*• * Remote4

JFY2024 SuperKEKB operation plan



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2
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Central substation(150MW) switching works.

• With the inital budget allocated by MEXT, it seems likely that the rings will only be able tooperation for three months until July (due to huge electricity costs).
• With additional operating budget by KEK, we will be able to operate the rings aftersummer, maybe 1.5 month.
• If there is a supplemental budget from MEXT, it will be possible to operate in March (andprobably in December).

5Budget for SuperKEKB Project Same level as JFY2023• Budget for JFY2023 was extremely tight, in reality.
JFY2024 Budget

Ring
11%

Electricity cost
Computing (Belle II)
Facility maintenance

Linac (KEKB)
11%

Belle II
4%

Radiation Safety
Radiation Safety
2%Electricity cost
52%

Belle II
Linac (KEKB)
Ring
Outsourceing (Operators)

Facility maintenance
6%

Fixed term staff
L He and N2
Other common use

Computing (Belle II)8%6Supplemental budget form KEK for anti-aging measures
 JFY2023• Repair of cooling water system, especially inverter system of the pumps.
• Plan have been scaled back and delayed (significantly) due to bidding failures (several times) due to soaring
prices and major delays in parts delivery.
• First repairment is scheduled for summer 2024.

 JFY2024• The cost of measure to prevent aging of power supplies and magnets will be taken.

7Human resources (JFY2024)
 ACCL 3rd (Head: Kyo Shibata)• Safety, Vacuum, RF system, ARES cavity, SC cavity, Cryogenics• Prof: 3, Assoc Prof: 6, Assist. Prof. 3 , Technical Staff: 9, Senior Staff: 9 PD: 2

 ACCL 4th (Head: Makoto Tobiyama)• Control, Beam Transport, Beam Instruments, Magnet, SC Magnet, Commissioning• Prof. 3, Assoc Prof. 7 Assist Prof : 5, Technical staff: 9, Senior Staff: 8

 ACCL 5th (Head: Hiroyasu Ego)
• Prof. 6, Assoc Prof. 6, Assist Prof. 5, PD 1, Technical Staff: 7, Senior Staff: 118

Academic Staff

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Technical Staff

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International Collaboration
 MNPP-01 (R&D for high energy colliders)• SLAC, IHEP, CERN, IJCLab, INFN US-Japan collaboration• R&D for SuperKEKB and the next generation high luminosity colliders(SLAC, ANL, BNL, FNAL..)• Development and Study of Superconducting Magnet Upgrades for SuperKEKB(BNL, FNAL)• etc..

 Many young collaborators have been joined the commissioning of the rings after LS1• Supported by EAJADE program in EU.
• >15 young scientists have been contributing.

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Vacuum works during LS1 at a glance (MR): Area open to dry nitrogen or atmosphere

LER

Collimator head replacement (D02V1)

Collimator head replacement (D01V1)
Collimator relocation(D03V1 -> D05V1)IR works

Temporary countermeasure against
vacuum leak from beam pipe welding line
Installation of new bellows
chambers with SR masks

NEG pump feedthrough replacement(Vacuum leak)

Removal and reinstallation of
kicker ceramic chambers formagnetic field measurement
26th March 2024

HERIR works
Gate valve & bellows chamber
replacement

NLC (D05V1) systemconstruction
Collimator head replacement(D05V1)

Bellows chamber replacement(vacuum leak)Ion pump feedthrough replacement(Abnormal discharge, Vacuum leak)

Collimator head replacement(D06V1, D06H3)Installation of HOM absorberchamber
Collimator head replacement(D06H3, D06H4)
Collimator relocation(D06H1 -> D06H4)

Collimator head replacement(D09V1)

Injection septum &chamber replacement

The 27th KEKB Accelerator Review Committee

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Vacuum works during LS1 at a glance (BT&DR): Area open to dry nitrogen or atmosphere
Installation of V-offset bellows chambers (BTp)Installation of CSR monitor chamber (BTp)BTDR

Installation of OTR screen monitor (BTp)

RF cavity work
Removal and reinstallation ofbellows chambers for magnet
alignment (BTe & BTp)

26th March 2024

Removal and reinstallation of Ext. kicker
chambers for Kicker PS work

The 27th KEKB Accelerator Review Committee

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Major upgrade items of LS1
 Replacement of damaged collimator heads on both rings.
 QCSR cryostat vacuum leak
 Aperture enlargement of injection channel and modification of injection final septum ofHER.
 IR radiation shield modifications.
 Non-linear collimator at OHO straight section of LER.
 Installment of beam loss monitors/ acoustic sensors/ bunch oscillation monitors tomonitor sudden beam loss event.
 DR kicker power supply maintenance.
 Detailed story will be presented by the individual talks.

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T. Oki

2023/3/22

SKEKBルミノシティ問題対策会議

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Aperture enlargement of HER injection channel• Problem of HER injection

No enough room

• Wall can be an obstacle to injection.

wall• A wall should be placed between beam channels
for stored beam and injected beam.
• Injected beam orbit is too close to the wall.
• High levels of radiation detected at the injection
BPM chamber indicates that the injected beamhits the wall.
• It is hard to modify the injection beam orbit.
⇒ it is necessary to enlarge the horizontal apertureof the injection channel.
N. Iida (2022.1.21) BITF meeting•

What is planned during LS1•

Replacement of three beam chambers with newones.
• Update of injection BPM⇒ More precise injection tuning
2022/22/Feb.

M. Kikuchi (2021.12.03)
BITF meeting
BPAC

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IR radiation shield modification

K. Nakamura

New heavy metal shield on IP bellows
Y. Arimoto

K. Nakamura (2022.02.04)
10th SuperKEKB long-term
operation plan meeting
2022/22/Feb.

BPAC

Material change from W to SUS (QCS cryostat front plate)(Tip of QCS cryostat will be modified to make more space)17

QCS-R re-install Re-tried on 23/Oct/2023 with• Modified RVC gear
• Modified VXD cable support• The QCS supports was carefully advanced by Tanaka-san.

 RVC worked very smoothly– no vacuum leak found.

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IR radiation shield modification• Additional concrete shield (IR) & polyethylene shield (Belle2)• For shielding fast neutrons• New concrete shields and polyethylene (PE) shield will be added to a spacethat currently has no shield.
• Additional PE shields around QCS are also planed.

• Expected effects of shield modification• Physics run with wider collimator setting• Physics run with larger total currents and bunch current

Add concrete shields

Add PE shields

shield mockup

PE shield

H. Yamaoka (2021.11.04)
IR meeting

H. Yamaoka (2021.11.04) IR meeting
2022/22/Feb.

BPAC

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NLC construction
Tsukuba (Belle II)• Non-linear collimator (NLC) is being installed in LER
Oho straight section.
Conventional collimation scheme

D04
D05

collimator

2023/26/June

Positronbeam

Small aperture can makebeam unstable.

Non-linear collimation scheme (conceptual diagram)
Skew
Quad.
Sext.

First Sextupole magnet kicks
unwanted beam particles.

Ohostraight section• Impedance of NLC is much lower than that of conventional
collimator due to its large aperture.
• NLC can relax TMCI bunch current limit.
• Oho straight section is the location where the optics satisfies
the requirements for NLC.
• A part of wiggler magnets need to be removed.
• New skew sextupole magnets and beam pipes in them needto be fabricated.
• New power supplies, cabling works and new radiation
shields are also required.

Oho lab.

collimator

Collimator scrapes unwanted beam
particles with large aperture.
BPACSkew
Sext.

Quad.

Second sextupole magnet brings goodbeam particles back to their original angle.
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2021c physics run

D06V1

βy*=1 mm
βx*=80 mm

LS1後

D06V1
D05V1
Photo of the non-linear collimator section (2023-05-26)

D05V1

SNAP.1(not installed yet)• Σβyky will reduce from 3.97e4 downto 3.18e4 V/pC
• Threshold of TMCI is estimated to increase more than
2.mA/bunch

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Nonｌinear Collimator22Nonlinear Collimator

23Other Collimators
D01

D01H4 D01H5 D02H4 D02H3 D02

IRe-

D12V4
D12D12H4
D12V3
D12H3
D12H2
D12V2
D12H1
D12V1

TSUKUBA

D03
D03H1

SuperKEKB Main Ring

D05V1

: Vertical Collimator, KEKB HER(50x104) type

D10

D09V4
D09H4
D09V3
D09H3
D09H2
D09H1
D09V2
D09V1

WIGGLERWIGGLER

OHO

NIKKO

SC
WIGGLERSC: Horizontal Collimator, KEKB HER(50x104) type

ARES

D04

LER

HER

ARES

D11e+

D02H1
D02V1 D02H2

D01V1
D01H3

: Horizontal Collimator, SuperKEKB LER(f90x220) type

D05

: Vertical Collimator, SuperKEKB LER(f90x220) type
: Horizontal Collimator, SuperKEKB LER(f90) type
: Horizontal Collimator, SuperKEKB HER(f80x220) type
: Vertical Collimator, SuperKEKB HER(f80x220) type
D06V2

FUJI

D09

e-D08

D06V1
D06H4
D06H3

e+

D06

D0724

Status of LER collimator
Name

TypeTip Material(): longitudinal length in mm

Tip Condition

Remarks

D06H3

SuperKEKB

Cu coated C (160)

healthyspoiler against inj. kickers’ accidental firings

D06H4

SuperKEKB

Ta (10)healthyabsorber against inj. kickers’ accidental firings

D03H1

SuperKEKBW (10)

healthy

D02H1

SuperKEKBW (10)

healthy

D02H2

SuperKEKBW (10)

healthy

D02H3

SuperKEKBW (10)

healthy

D02H4

SuperKEKBW (10)

healthy

D06V1

SuperKEKB

Cu coated Ti (10)healthy

D06V2

SuperKEKB

hybrid (3)healthy

D05V1

SuperKEKB

Cu coated Ta (4)healthy

D02V1

SuperKEKB

Cu coated Ta (10)healthy25

Status of HER collimator
Name

Type

D09H1
D09H2
D09H3
D09H4
D12H1
D12H2
D12H3
D12H4
D01H3
D01H4
D01H5

KEKB
KEKB
KEKBKEKB
KEKB
KEKB
KEKB
KEKB
SuperKEKBSuperKEKBSuperKEKB

D09V1
D09V2
D09V3
D09V4
D12V1
D12V2
D12V3
D12V4
D01V1

KEKB
KEKB
KEKB
KEKB
KEKB
KEKB
KEKB
KEKB
SuperKEKB

Tip Material
Tip Condition(): longitudinal length in mm
Cu coated Ti (40)damagedCu coated Ti (40)damagedCu coated Ti (40)damagedCu coated Ti (40)damagedTi (40)healthy
Cu coated Ti (40)damagedTi (40)healthy
Cu coated Ti (40)healthyW (10)healthyW (10)healthyW (10)healthy
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ti (40)
Cu coated Ta (10)healthyhealthyhealthyhealthydamageddamagedhealthyhealthyhealthy

Drive Mechanism

Remarks

upgraded

upgraded
upgraded
upgraded-26

Spare jaws
Tip Material(): longitudinal length in mm

Collimator to be installed(assumed)

Remarks

HER vertical: Cu coated Ta (10)D01V1

Plan to deliver in this fiscal year.

HER vertical: Cu coated Ta (10)D01V1

Plan to deliver in this fiscal year.

HER vertical: Cu coated Ti (40)

D09V1-V4, D12V1-V4

HER vertical: Cu coated Ti (40)

D09V1-V4, D12V1-V4

LER vertical: Cu coated Ta (10）D02V1

LER vertical: Cu coated Ta (10）D02V1

LER vertical: hybrid (3）D05V1, D06V1-V2

LER vertical: hybrid (3）D05V1, D06V1-V2

LER vertical: Cu coated Ta (10)

D02V1, D05V1, D06V1-V2

Plan to deliver in this fiscal year.

LER vertical: Cu coated Ta (10)

D02V1, D05V1, D06V1-V2

Plan to deliver in this fiscal year.

LER horizontal: Ta (10）

D06H427

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 headReplacement 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 atHER injection point

New beam pipes with wider aperture & New BPM for precise measurement ofinjected 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 currentDR••

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
2023/3/22

DR RF section

Modification : December 2022  August 2023

• And so on…
SKEKBルミノシティ問題対策会議

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Injector Linac
 Replaced 16 old accelerating structures with new ones (with larger energy gain).
• Starting fabrication of 12 additional accelerating structures New fast kickers (kick first and second bunch independently), larger aperture pulsedQs have been installed.
• Sucessful beam tuning using machine-learning method (Bayesian optimization)

 Study of BT beam blowup• Rejected the CSR-induced beam blowup in positron line
• Still hunting the cause of blowups.

 Next step••••

Beam diagnostic line at SY3
BTe-ECS(2024-2025)
Beam optimization
etc..

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Summary Thank you so much for your participation in this 27th KEKB Accelerator Review.
 We plan to operate SuperKEKB rings at least 4.5 month.
• 2024a 29/Jan to 31/Mar, 2024b 1/Apr to 1/Jul. 2024c 9/Oct to end of Nov.??
• Hoping to receive supplemental operation budget to enable longer operation, especially on Mar/2025.

 Accelerator works of Long shutdown 1 was completed almost on schedule andresumed the beam operation.
 Please refer to the following presentations for the achievements of this LS1.

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Backup slides

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