Status of Accelerator Upgrades
during LS1
BPAC
Kyo Shibata (KEK Accelerator Laboratory)
2023.06.26

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• Upgrade items during LS1• MR upgrade• Injector Linac upgrade• Others• Summary

2023/26/June

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Contents• Upgrade items during LS1• MR upgrade• Injector Linac upgrade• Others• Summary

2023/26/June

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Upgrade Items• To overcome challenges of accelerators, upgrade works are undergoing now.
Challenges as Lumi. Frontier machine
1. Short beam lifetime
2. Beam instabilities
3. Low machine stability
4. Low Injection efficiency

Luminosity after LS1 : ∼2.4×1035 cm−2s−1
 Increasing total beam currents
 Increasing bunch current
 Squeezing βy*2023/26/June

Major upgrade items• Radiation shield enhancement at IR• Non-linear collimator with low impedance in
LER• Robust collimator head in LER• Modification of HER injection point• Pulsed quad. magnet at Linac• New accelerating structure at Linac• Fast kicker for 2nd bunch orbit correction at
Linac• Magnet alignment at BT• Etc.
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Schedule
Ceiling aseismic reinforcing work

• LS1 : from July 2022 to December 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 December 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 reinforcement of ceilings in the laboratory buildings (Oho Lab., Fuji Lab. and Nikko 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

2022

JFY2022

4

5

6

7

8

2023
9

10

11

12

1

2023/26/June

4

5

3

Long Shutdown 1 (Accelerator upgrade)
Belle II maintenance & reinforcement
Ceiling aseismic reinforcing work (Fuji & Oho)

2022b run

2023

JFY2023

2

6

7

8

2024
9

10

Long Shutdown 1 (Accelerator upgrade)
Belle II maintenance & reinforcement
Ceiling aseismic reinforcing work (Nikko)
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11

12

1

2

3

2024a run2023c run5

Contents• Upgrade items during LS1• MR upgrade• Injector Linac upgrade• Others• Summary

2023/26/June

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IR (Tsukuba straight section)
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
Reported in this talk
• QCS cryostat modification
Concrete radiation shieldIR

Tsukuba lab.

PositronbeamElectronbeam
QCS cryostat

IR (Tsukuba straight section)
2022
4

5

6

JFY20227

8

Concrete shield disassembly

2022b run

2023
9

10

11

12

1

2

Magnet & beam pipe disassembly
QCS extraction
QCSR cryostat leak test

3

QCS cryostat
modification
Belle II maintenance & reinforcement

2023
4

5

6

7

8

2024
9

QCS reinstallation
Magnet & beam pipe assembly

JFY2023
Belle II
maintenance & reinforcement
2023/26/June

10

11

12

1

2

3

Concrete shield reinstallation
2024a run2023c run

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QCS cryostat modification #1
IR• To reduce Belle II background noise;

Tsukuba lab.

• Material at the tip of QCS cryostat was changed from W to SUS• To make more space for Belle II cables;• QCSR cryostat tip shape was modified to be thinnerElectronbeam• For these upgrades• FWD side : QCSR cryostat front cap replacement, Modification of inner structure of QCSR
cryostat to fit thinner front cap
BPM feedthroughY. Arimoto• BWD side : QCSL cryostat front plate replacement

Positronbeam

BPM feedthroughQCS beam pipe

QCS beam pipe

QCS beam pipes must be
moved for these works!!

To 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
2023/26/June

QCSR front cap
replacement
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QCSR
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QCS cryostat modification #2• QCS cryostat modification works were successfully completed.

T. Oki

QCSL

2023/26/June

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New concrete shields
IR• New concrete shields have been delivered to Tsukuba experimental hall.

Tsukuba lab.

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

PositronbeamThis space will befilled with concrete.

This shield will be replaced withnew one.

New concrete shields

Concrete shield disassembly work
2023/26/June

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H. Yamaoka
10Vacuum leak repair at QCSR cryostat
IR• Pressure in QCSR cryostat has been higher than that in QCSL cryostat.

Tsukuba lab.

• Vacuum leak test before LS1 did not detect any vacuum leaks.
• Location of the vacuum leak was identified by the vacuum leak test after QCS extraction!!

• Repair works were made at the same time as the cryostat modification works.
• Service cryostat at QCSR was opened to check the vacuum sealing (O-ring), and a fiber-like object was
found on the O-ring surface.
• O-ring was replaced with new one.
QCS-R service cryostat• Vacuum sealing surfaces were cleaned.

Electronbeam

Positronbeam

Y. Arimoto

Fiber-like object

O-ringVacuum leak test of QCSR cryostat
2023/26/June

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

D05 wiggler section

Tsukuba (Belle II)
Oho lab.
Ohostraight section• Disassembly and reinstallation of concreteradiation shields
Reported in• NLC construction (LER)
this talk• RF cavity replacement (LER)• Ceiling aseismic reinforcing work
• Installation of new radiation shields for NLC

D04
D05

Positronbeam

S. Nakamura

Oho straight section (D05)
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

RF cavity replacement

2024
9

10

11

12

NLC construction
New radiation shield
installation

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NLC construction

2023
4

2

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1

2

3

2024a run
Concrete shieldreinstallation

2023c run
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NLC construction #1
Tsukuba (Belle II)• Non-linear collimator (NLC) is being installed in LER
Oho straight section.

Conventional collimation scheme

D05

collimator

2023/26/June

Positronbeam

Small aperture can makebeam instable.

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

First Sextupole magnet kicks
unwanted beam particles.

D04

Oho
straight 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 need
to 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.
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Skew
Sext.

Quad.

Second sextupole magnet brings good
beam particles back to their original angle.
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NLC construction #2
Tsukuba (Belle II)• Wiggler magnets and beam pipes were removed.
••••

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
2023/26/June

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Oho
straight section• Removed wiggler magnet and cable : 50 magnets and their cables

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NLC construction #3• Relocation of the quadrupole magnets and re-wiring between the power supply and themagnets have been completed.
• New skew sextupole magnets and one power supply will be installed in September.

• Collimator and almost all beam pipes have been installed.

• Collimator D05V1 was relocated from D03V1.
• Beam pipes for the skew sextupole magnets will be installed after skew sextupole magnet installation.

← IP (Tsukuba)
After

Skew sextupole magnet
2023/26/June

S. Nakamura

Wiggler magnets were removed.

New collimator (D05V1)
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HER(e-) →Skew sextupole magnet

LER(e+) ←15

NLC construction #4
2023/June/14

Skew sextupole magnet andbeam pipe will be installed here.

Skew sextupole magnet andbeam pipe will be installed here.

D05V1 collimator (NLC)
2023/26/June

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NLC construction #5• New radiation shields are required to protect Oho experimental hall.

• New Pb radiation shields will be installed 5m-downstream region of D05V1. (Octorber)• New concrete shields will be installed to fill the space between the SuperKEKB tunnel and the existing
concrete shields. (November)Pb shield at Tsukuba straight section

D05V1
collimator

New Pb shield(currently under production)

Existing concrete shields

5m
New concrete shields(delivered in early July)
D05V1
collimator
2023/26/June

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HER injection point
Tsukuba (Belle II)• Required upgrade to improve HER injection efficiency (what we have learned from beam
operation until 2022b);• Enlargement of the horizontal aperture of beam pipe
• Replacement of beam pipes at injection point with new one with larger aperture (last week)• Reduction of amplitude of horizontal oscillation of injected beam
• Replacement of injection septum magnet with new one with improved magnetic field (Oct.)
Aperture enlargement
is required here.

Fuji lab.
Electron
beam

D08
Fuji
straight section

wall

Septum mag. will
be replaced.

Stored beam
Injected beam
Septum mag.

M. Kikuchi (2021.12.03)
BITF meeting

Magnetic field will be
improved.
2023/26/June

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Beam pipes were
replaced.
18Collimator head replacement• LER

T. Ishibashi• D02V1, D06V1 : SuperKEKB type, Damaged by Sudden Beam Loss
• D02V1 : Ta -> Ta with Cu coating• D06V1 : Ta -> Ti with Cu coating• D06H3 : SuperKEKB type, Damaged by injection kicker-pulser misfiring• Ta(in), W(out) -> C with Cu coating (Low-Z robust head)• D06H1 (upstream of D06H3) was relocated to D06H4 (downstream of D06H3)
to collimate the beam passing through D06H3.
• To prevent misfiring, long-term conditioning of injection kicker will be performed
before beam operation.

relocation

D05V1
(NLC)

• HER

• D01V1 : SuperKEKB type, Damaged by Sudden Beam Loss
• W -> Ta with Cu coating• D09V1 : KEKB type, Damaged during KEKB operation

relocation• Ti -> Ti, Cu coating (not yet)
• Replacement work will be done in September.

D06H4• All newly installed heads have a Cu coating.

• Low impedance• Countermeasure against Sudden Beam Loss (based on Fireball hypothesis)2023/26/June

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Construction site of
non-linear collimator

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Contents• Upgrade items during LS1• MR upgrade• Injector Linac upgrade• Others• Summary

2023/26/June

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Injector Linac upgrade #1
For injection efficiency
improvement;•••

New pulsed Quads for thesimultaneous dedicatedmatching of HER/LER
injection beam
New pulsed Quads for low
beta optics of HER injection
beam
Fast kicker for 2nd bunch
orbit correction

For stable operation;••

New accelerating structure
Replacement of air
conditioners in the tunnel

M. Satoh2023/26/June

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Injector Linac upgrade #2• Pulsed Quads (x8) for the simultaneous dedicated matching of HER/LER injection beam will be installed at J-ARC.
M. Satoh••

Without pulsed Quads, only
the HER injection beam
could be tuned well.
With these pulsed Quads,
both HER and LER injection
beam can be tuned well.

Improvement of LER
injection beam

2023/26/June

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Injector Linac upgrade #3• Pulsed Quads (x4) for low beta optics of HER injection beam will be installed at Sector1&2.
M. Satoh••

After only these four pulsed quads
are optimized for the e- beam, theβ-function can be decreased.
Simulation result shows that it canhelp to decrease the emittance lessthan half.
+ Fast kicker fore- 2nd bunch tuning
Improvement of HER
injection beam

2023/26/June

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Injector Linac upgrade #4• 5-year upgrade plan to fabricate and install new accelerator structures is in progress now.
M. Satoh2023/26/June

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Contents• Upgrade items during LS1• MR upgrade• Injector Linac upgrade• Others• Summary

2023/26/June

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Others• RF cavity modification and replacement (LER)• For stable operation with larger beam current• BT magnet re-alignment (BT)• For injection efficiency improvement• CSR measurement system (BT)MR

• For injection efficiency improvement• Vacuum seal replacement at RF section (DR)• For stable operation (pressure reduction)• DR Extraction kicker power supply modification and repair (DR)T. Abe• For stable operation & injection efficiency improvement• Improvement of RF-gun laser window degradation (Linac)• For injection power improvement• Precise beam tuning with beam monitors at J-ARC (Linac)

DR• For injection power improvement & injection efficiency improvement• And so on…

RF cavity replacement

CSR measurement system

T. AbeDR Ext. kicker
2023/26/June

Vac. seal replacement
at DR RF section

M. Satoh

Beam tuning with SR monitors in J-ARC

S. Terui
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Contents• Upgrade items during LS1• MR upgrade• Injector Linac upgrade• Others• Summary

2023/26/June

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Summary• Many works are in progress during LS1• LS1 started in July 2022 and will end in early December 2023.
• Belle II works are also underway.
• Beam operation is scheduled to resume in December 2023.

• Major upgrade items :• Radiation shield enhancement at IR• Non-linear collimator with low impedance in LER• Robust collimator head in LER• Modification of HER injection point• Pulsed quad. magnets at Linac• New accelerating structure at Linac• BT magnet re-alignment• Etc.

• Major maintenance items :• Damaged collimator head replacement• Repair of vacuum leak in QCSR cryostat• RF cavity modification and replacement• Repair and modification of DR ext. kicker power supply• Etc.

• All planed works are being performed almost as scheduled so far.
• Accelerator upgrades will be completed in early December 2023.
• Schedule is very tight, and strict process control is required.
2023/26/June

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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

2023/26/June

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