SuperKEKB
near-term (until 2021c) andlong-term operation plan
Y. Suetsugu
KEK Acc. Div.

2021/2/8

B2GM

1• Near-term (until 2021c) operation plan
• Long-term operation plan

2021/2/8

B2GM

2

Brief review of MR in 2020c run• The 2020c run started on 19th Oct. and ended on 18th Dec., as scheduled.
• In summary, the 2020c run was very challenging one.
• The operation condition has been far from that in 2020b run.
• Imax(LER) = 690 mA (27th Nov.), Imax(HER) = 600 mA (24th Nov) during vacuum scrubbing.
• Max. peak luminosity was 1.48E34 cm-2s-1 (14th Nov.).
• Min. βy* was 1.0 mm.
Details will be reported• Various challenges and limitations were revealed.
by Mitsuka-san later.
2020c run summary (2020/10/19~2020/12/18)

2021/2/8

B2GM

3

Brief review of MR in 2020c run• Achieved luminosity and other major parameters
Int. L [fb-1] (Delivered)Lp [x1034 cm-2s-1]

Min. βy* [mm]From 2019c run

~4.2

1.0

~1/3
~1.5

0.6

Max. I [A]

(

*

~100

Beam dose [Ah]

βy*

~740
~2/3
~500

 Original Plan Result until
2020c

~110

Plan

~1729
~1577

Lp

Int. L

Imax

Beam
dose

0.6 ~4.2E34 ~110 ~740 ~1720

Result 1.0 ~1.5E34 ~100 ~500 ~1580*Note: in the plan, the ratio of LER/HER beam currents are
assumed to be 3.6/2.6, i.e., the ratio of the design currents.

2021/2/8(Geometric mean)

B2GM

4

Brief review of MR in 2020c run• Main causes of the low luminosity• Lower beam currents than expected (~500 mA < ~740 mA)• Low injection efficiency• Unstable beams from BT and Linac• Time change (periodical change and drift) of beam orbits, energy spreads• Frequent break downs of RF-gun cavity• Low injection efficiency on HER (not “explosion” although still large)• Low physical aperture at injection points?
• Short lifetime due to small physical and/or dynamic aperture in the ring
• High background (especially background by injected beam)• Sometimes depended on optics.
• Beam-size blow-up due to beam instability caused by collimator impedance in LER• Beam-size oscillation and/or blow-up due to beam-beam effect at high bunch currents• Hardware troubles -> limit max. beam currents.
• Beam collimator, Cooling water system• Larger βy* than expected (1.0 mm at most > 0.6 mm)• Little time to try the low βy*. Even the condition of βy* = 1 mm has not been resumed.

• As a result, integrated luminosity was also lower than expected.
2021/2/8

B2GM

5

Operation plan for 2021 runs
• 2021 Run schedule• 2021a run will start on 16th Feb.
• The first week will be only LER and will be dedicated to vacuum scrubbing and studies.
• HER will start from 24th Feb.
• The total operation period will be ~6.4 months this year, thanks to the support from our director.

• The process for the FY2021 budget request is ongoing.
• We will aim for 5.7 months’ operation in FY2021 (taking account of the long shutdown for the PXD
replacement from Jan., 2022).

• Major premise for 2021 runs
• 2021 runs should be dedicated for the luminosity production.
• Produce new physical results from enough data, over 424.18 fb-1 (final integrated luminosityof BaBar, NIM A726 (2013) 203) at least by the end of December, before the long shutdown.
Realize stable operation at a high luminosity.
Present plan2020
4

FY2020

5

6

7

8

9

10

2020b

Present plan (20th Oct.)
2021
4

FY20212021/2/8

4/1

~3.1M

2021
1

2

6

7

8

9

10

11

3
2021a

~2M

2021b

Plan (not fixed)[MEXT Road Map]

12

2020c

~3M
5

11

12

2022
1

~1.5M
2

3

2021c
10/7

7/5

B2GM

~2.6M

12/23

Total

~6.5M/yPXD exchange

Total~5.7M/y6

Operation plan for 2021 runs
• Run strategy• Run strategy until 2020b run• Squeeze βy* and increase luminosity with moderate total beam currents within the limited
background level, and then accumulate the data.
• Suppress the increase in background resulting from βy* squeezing by adding or closing collimators.
• Generally successful until 2020b• Achieved the world-record luminosity with moderate beam currents in 2020b at βy* = 1 mm.

• 2020c run followed the strategy• Planned to squeeze βy* down to ~0.6 mm and improve luminosity further.
• Add D03V1 collimator• However, lots of challenges were standing in the way before squeezing βy* down toless than 1 mm.
• High background and low injection efficiency (unstable conditions of injection beam).
• Strong beam instabilities (TMCI) due to high impedance of collimators• Strong beam-beam effects at high bunch currents• Beam currents of ~600 mA at most, as a result.
• The situation would be worse if βy* is squeezed further in this condition.

Revise the strategy to achieve the goal of 2021 runs, through discussion
with Belle II
2021/2/8

B2GM

7

Operation plan for 2021 runs
• Run strategy• Run strategy until 2020c• Squeeze βy* and increase luminosity with moderate total beam currents within the limited
background level, and then accumulate the data.
• Suppress the increase in background resulting from βy* squeezing by adding or closing collimators.

• Revised run strategy for 2021 runs (proposal)• Put priority on (Int.) luminosity rather than background.
• Relax the background limit, for example, the TOP hit rate, which has been sometimes amajor limit of increasing the total beam current.
• Open collimators within the tolerable range, which could increase injection efficiency anddecrease the impedance• Aim at stable operation• Remove the high-impedance carbon collimator to avoid beam instability.  Done.
• Use the proven optics with βy* of 1 mm.
• Increase the total beam current by increasing the number of bunches and run within amoderate bunch current.
• Establish stable injection condition (essential).

2021/2/8• Of course, we will continue the effort to understand various issues, such as beam-beameffects, collimator damages, and to further squeeze βy* for the future.
• We will be able to get experience atB2GM
high current, too.
8

Operation plan for 2021 runs
• Basic run plan for 2021 run
1. Resume the ring condition at βy*= 1 mm, which was realized in 2020b run.

• The starting point. Peak luminosity of ~2.4E34 cm-2s-1 at ~700 mA, 978 bunches.
• It will take one month (by the end of March)?
• Establish stable beam injection condition.
• Use the proven optics, which had been used when the maximum luminosity was recorded in
2020b (reduction of background by D03V1 will not be expected.)

2. Gradually increase beam currents at βy* = 1 mm with
1565 bunches.
• TOP could relax the limit on the background from 1.2 to 5
MHz/PMT, which allows to increase total beam currents.
• Considering the possibility of replacing PMT in 2026.
• 5 MHz/PMT, for example, corresponds to LER =1.6~1.8 A.

• The number of bunches might be increased step by step,
depending on the machine condition.

3. Option: Squeeze βy* down to 0.8 mm (and more)• If possible and if there is any indication to raise luminosity.
• Note: We will not stop challenging lower βy* for the future.

2021/2/8

B2GM

K. Kojima

9Operation plan for 2021 runs
• Basic run plan for 2021a, b• Rough schedule (Draft)
SuperKEKB 2021a, b Operation Plan

2020
February1

BT Study

11

March
16

21

1

April

11

21

1

11

May
21

1

11

June
21

1

11

July
21

1

11

Linac, DR, BT Tuning

MR

16

10

7

24

21

12

26

9

23

5

Owl shift(LER)

Day shift
Swing shft
Machine study 54 Shifts

Physics run 345 Shifts
Linac study

0 Shifts

Maintenance 20 Shifts

Total 419 Shifts

2021/2/8

β y* 8.0 2.0 mm
Number of bunches

1.0 mm~978 (basically)~1565 (basically)

Luminosity tuning
Vacuum scrubbing(LER)
Injection tuning
Optics tuning
Collimator tuning
Background tuning

Injection tuning
Optics tuning
Collimator tuning
Background tuning

B2GM

Tunings will be continued in parallel with physics runs.
Studies will be planned, as necessary.

10Luminosity profile for 2021 runs
• The luminosity profile was re-evaluated based on the results of 2020c and following
the strategy for 2021 runs.
• Assumptions for revaluating luminosity projection• Beam current  Key point• Considering the results of 2020c run, it seems reasonable to assume that the beam current willbe 1.1 ~ 1.2 A, although the TOP limit is relaxed.

• Specific luminosity• Same level to 2020b run• Expected to be improved gradually by ~10%?

• Others• The luminosity used for the calculation of Int.
Luminosity is 0.65 times of the peak luminosity, which
has been assumed to be 0.7 so far.
• Physics run for 28 days per month basically.
• Move to 1565 bunches from 4/1.
• The Int. luminosity includes that during the off-resonance run.
• ~1 week?

Y. Funakoshi• Reduction in dP/dI ~ 60% at 6000 Ah.
• No long-term break• No trouble in collimators and other hardware (~1 week break in the case) -> ~10 fb-1 loss

• No intervene by COVID-19
2021/2/8

B2GM

11

Luminosity profile for 2021 runs
• Base plan : Maximum beam current ~1.1 A by the end of 2021b.
Min. βy* [mm]978Int. L [fb-1] (Delivered)Lp [x1034 cm-2s-1]
1565

978

Lpx0.65 (2021a~) 978

1565

1565

From 2019c run

From 2019c
~430

~4.7
~3.8

1

Max. I [A](Beam dose [Ah]
~1.1A

978

~270

Lsp x βy* [E31 mA2]

1565
~6000
Result in 2019c

9782021/2/8

1565

B2GM

 Revisedplan Result
until
2020c

Note: Constant Lp
was assumed
even for ib+*ib- >0.6 [mA2]

12

Luminosity profile for 2021 runs
• Possible plan : Maximum beam current ~1.2 A by the end of 2021b.
Min. βy* [mm]Int. L [fb-1] (Delivered)Lp [x1034 cm-2s-1]
978

1565

Lpx0.65 (2021a~) 978 1565
~5.7

From 2019c

~4.5
~300

1

Max. I [A](Beam dose [Ah]
~1.2A

978

From 2019c run
 Revisedplan Result
until
2020c

Lsp x βy* [E31 mA2]

1565
Result in 2019c

978

~490

Note: Constant Lp
was assumed
even for ib+*ib- >0.6 [mA2]

1565

2021/2/8

B2GM

13

Short-term operation plan
• Summary• Run strategy for 2021 runs: Put priority on (Int.) luminosity rather than background.
• Base and possible plans : Maximum beam current 1.1~1.2 A by the end of 2021b.
Max. I [A]Int. L [fb-1] (Delivered)Lp [x1034 cm-2s-1]

(
~1.2A

978

1565

Lpx0.65 (2021a~) 978
~5.7

~1.1A

978

~4.5

~4.7

• How much can we store the beam currents?
• Can we keep the injection condition stable?
• Can we control beam instability and beambeam effect at high bunch currents?
B2GM

 Revisedplan Result
~490
until
~430
2020c

~300
~270

• Key point to realize the plan

2021/2/8

From 2019c

~3.8

1565

1565

From 2019c runβy*

Lp [E34]

Int. L [/fb]Imax~2021b

1.0

3.8~4.5

270~300

1.1~1.2~2021c1.0

4.7~5.7

430~490

1.2~1.3

1.5~2 fb-1/day

14

• Near-term (until 2021c) operation plan
• Long-term operation plan

2021/2/8

B2GM

15

Long-term operation plan
• For MEXT Roadmap 2020, we proposed to update the previous long-term operation
plan (2019) considering the actual situation and the results obtained until 2019c.
Operation plan proposed for MEXT 2020 Roadmap

2021/2/8

B2GM• Peak luminosity ~6E35 cm-2s-1 in ~2028• Integrated luminosity 50 ab-1 in ~2030 (40 ab-1
in ~2029)• PXD exchange in 2021~2022• Partial RF-power upgrade (2 stations) in 2026
• IR (QCS and its beam pipes etc.) upgrade in2026• βy*=0.3 mm in 2026 after IR upgrade, and ~0.5mm before that• Max. beam currents: LER 2.8 A, HER 2.0 A(1761 bunches) in 2027
• Basically, 8 moths’ operation per year.
[Investment in equipment]• QCS and its beam pipes etc.
• Partial RF-power upgrade (2 stations)• Beam collimator upgrade• Linac upgrade• Belle II upgrade

16

Long-term operation plan
• Key point : Intermediate upgrade of IR around 2026
• Relocation of magnets: Make it possible to squeeze βy* to 0.3 mm, mitigate the beambeam effect in the high bunch-current region• Enlargement of QCS beam pipes: Protect QCS, and reduce the background.
Long-term Operation plan••

Improvement of• Background• Beam lifetime• Collision efficiency

Intermediate
remodeling of IR(QCS, Belle, RF

Remodeling of Linac

Boost up of luminosity
βy* : ~0.5  ~0.3 mm
Lpeak : ~3E35  ~6E35 cm-2s-1

Partial replacementof detectors• Until the upgrade, βy* will be
gradually squeezed, and thebeam currents will be increased
gradually.
2021/2/8

βy* [mm]B2GM

1.0

0.6

0.5

0.3

17

Long-term operation plan
• Present status• The MEXT updated their roadmap 2020 in August, 2020.
• The SuperKEKB/Belle II project was selected as one of 15 highest priority projects
with an “AA” grade (the highest possible).
• The actual plan will be finalized seeing the progress of the current luminosity
improvement.
• The plan was assessed by the external review committees (BPAC, 2020/6 andAccelerator Review Committee (ARC, 2020/7)).
• Based on the recommendation from the review committees, “Long-term operation
plan meeting” was launched in August, 2020.

2021/2/8

B2GM

18

Long-term operation plan meeting• In the meeting, the following issues are discussed and examined in these 2 or 3
years.
• Is IR upgrade really possible?

• Is IR upgrade really required?
• Examination of crab-waist scheme• Verification of the effect of rotatablesextupole magnets• Investigation of beam-beam effect• Understanding of background issue• βy* squeezing and luminosity• Understanding of beam lifetime• Collimators and their impedance issues• Injection efficiency• Examination of the base plan (withpresent QCS)

• Making practical model of QCS magnet
field configuration• Making practical beam optics• The range of remodeling• Examination of technical issues• Manufacturability、Materials of SC
cables、Magnet alignment method• Examination of human resources• Conflict with Belle II detector• IP chamber, Connection mehode• Manufacturing schedule• Commissioning after the upgrade• Short-term commissioning plan
• Establish the performance model• Four meetings have been held so far (~2021/2/4).
• In parallel, the issues of RF-upgrade, Linac and BT will be also discussed in themeeting.

2021/2/8

B2GM

19

Some topics in the meeting so far• Narrow dynamic aperture at high-bunch current regions due to strong beam-beameffectMagnetic fields around IR
•

•
•
•

•

A promising method to mitigate the effect was said to be
the modification of QCS to avoid interference between thequadrupole magnetic field and the Belle II solenoid field
for the LER.
Two ideas to relocate QC1P to places farther from IP
were examined at first.
However, up to now, it was found that little improvement
was expected even without beam-beam effect.
On the other hand, it was also found in a simulationthat the effect will be cured using the rotatablesextupole magnets installed in the local correction
region at Tsukuba.
We will try it this during 2021 run.

2021/2/8

B2GM

QCSR configuration

IP
N. Ohuchi

Rotatable Sextupole magnet

M. Masuzawa

20

Some topics in the meeting so far• Narrow physical aperture in the QC1RP -1• Enlargement of the (vertical) aperture of beam pipes in QC1RP has been discussed.
• The enlargement is expected to increase the physical aperture and then increase beam lifetime,and also to reduce background.
• Although little improvement in the lifetime determined by the dynamic aperture.
• The aperture can be enlarged by relocating the correction magnets to outside of the main
quadrupole magnets.

• It will be possible to increase the inner diameter from 13.5 mm to 18 mm geometrically.
• The range required for the modification was examined, and it was reported that themodification near to the BPM and bellows near to IP is also required.
Cross section of QC1P

Aperture of QC1P and beam sizes

N. Ohuchi
2021/2/8

N. Ohuchi

B2GM

H. Nakayama

21Some topics in the meeting so far• Narrow physical aperture in the QC1RP -2••

2021/2/8

The R&D for the beam pipes, BPM and bellows has started.
Required R&D• Beam pipes for QC1RP• Remodeling of connection flange at IP side（RVC）R&D
and testing together with DESY group.
• Change in the vacuum sealing mechanism between the
QCSR cryostat and the beam pipe. (O-ring seal)• Manufacturing method of beam pipes and TiN coating
method.
• Bellows chamber with BPM
Bellows chamber with BPM at IP• Change in the cross-section of
bellows from circular one to an
ellipse or a race-track one• Change in the flange at QCS
side.

B2GM

K. Kanazawa and K. Shibata

22Some topics in the meeting so far• Examination of the base plan (with present QCS)••

The performance with the present QCS is being
examined by a simulation including beam-beam effect.
Recently it was reported that the Touschek beam
lifetime will be increased by 60% and a luminosity ofaround 3E35 cm-2s-1 could be achieved by introducing
a “perfect match” and 40% of the crab-waist in LER.

Luminosity vs βy* (K. Oide)
CW=50%,
perfect matchℒ

CW=60%∗

CW=80%• ~3E35 cm-2s-1 : Goal luminosity before the upgrade.

•

How to practically realize the “perfect match” using
normal-conducting quadrupole magnets, for example, isbeing investigated.

Dynamic aperture with CW=80%ℒ∗

Dynamic aperture with CW=40% + “perfect match”
K. Oide2021/2/8ℒ“Perfect match”:• Phase shifts between
SLYTRP2/SLYTLP1 and IP arejust 0.5 (x) and 0.75 (y).
• The values of βx and βy at thecenter of four SLY（SLYTLP1&2,
SLYTLP1&2） are set to be thesame, respectively.
B2GM

23

Long-term operation plan
• Summary• Updated long-term operation plan was proposed for MEXT roadmap 2020 last year.
• Put the priority on the integrated luminosity, rather than the peak luminosity, and realize an
integrated luminosity of ~50 ab-1 within a reasonable time period.
• Modify the IR, especially upgrade QCS and its beam pipes around 2026, which should
boost the luminosity and achieve the goal luminosity.

• “Long-term operation plan meeting” was launched based on the recommendationfrom the review committees to discuss the detailed and practical issues in the plan
• Four times meeting so far, and following subjects were discussed and investigated.
• Relocation of QC1P to increase dynamic aperture• No clear improvement so far• Enlargement of physical aperture in QC1RP• R&D on beam pipes and bellows around QCS has started.

• Weakening of Belle II solenoid magnetic field (for ex., 1.5T1.2T)• Examination of the base plan (with present QCS)
• Practical method to realize “Perfect match” is under investigation.

• More major remodeling, including that of Belle II detectors.

• Some practical conclusion should be obtained in these two or three years, i.e., before
the decision of whether the IR have to be upgraded or not around 2026.
2021/2/8

B2GM

24

Thank you for your attention

2021/2/8

B2GM

25

Backup

2021/2/8

B2GM

26

Brief review of MR in 2020c run• Initial shift plan
• 60 days (120 shifts) in total.
1st

2nd

3rd

4th

5th

6th

7th

8th

9th

• Actual shifts• Most of day and swing shifts of weekdays were dedicated to beam studies and tunings.

Y. Ohnishi
2021/2/8

B2GM

27

Brief review of MR in 2020c run• Challenges in 2020c run• Internal leak in a SC cavity of HER• Poor injection efficiency (through 2020c)• Many reasons, such as mis-setting of magnet parameters in BT, frequent break-down of RF-gun
cavity, time change (oscillation and drift) of BT/Linac orbit and energy, narrow physical or
dynamic aperture of the rings, beam instability, and so on.

• Difficulty in squeezing HER βy* to 1 mm
• High background by injected beams• Damage of D02V1 collimator jaw, and exchange work (~1 week break)• Big air leak from D02V1 collimator flange• Difficulty in resuming the LER/HER condition after the collimator trouble• High background by injected beam with new steering-magnet settings• Failure in cooling water pump
• Coupled bunch instability in LER due to impedance of collimators• Strong excitation of TMCI with new phase-adjusted LER Optics• Vertical beam size oscillation and blow-up in HER due to beam-beam effect• Damage of D06V2 collimator jaw• Emittance growth at the latter part of the electron beam transport line
• Etc.

• Some were solved, but some were not.
B2GM

2021/2/8

28

Operation plan for 2021 runs
• Main hardware work during 2021 winter shutdown for 2021a run• Replacement of D11D SC cavity to a reserve (HER)• The completion inspection and the issuance of completion certificate as a high-pressure gas
device from the government agency, is expected in around mid of Feb.

• Replacement of D06V1 collimator jaws (LER)• From 60 mm carbon to 5 mm tantalum• Reduction in the impedance is expected.

• Replacement of D09V3 collimator jaws (HER)• KEKB type titanium jaw.

• Replacement of D12V1 collimator drive mechanism (HER)• More precise positioning is expected.

• In situ baking of D02V1 and D06V1 collimators (LER)• Reduction in the base pressure is expected.

• Installation of a collimator in the Linac electron line (BTe SY3)
• Replacement of aged 66 kV high-voltage power supply lines [by Facility Department]• Other maintenance works• Repairs of aged power supplies for magnets, etc.
2021/2/8

B2GM

29

Operation plan for 2021 runs
• Other improvements for 2021a run• Prepare an interlock system in case of cooling water trouble for vacuum system.
• Combined interlock with colling-water flow-meters and vacuum pressures.

• Prepare an alarm system which indicates a possibility of collimator damage.
• Combined alarm with pressure bursts and VXD signals.

• Prepare a software to restore, check, and compare various setting parameters in BT (suchas magnet settings) before starting run.
• Discussion has started together with Belle II staff.

• Lessons not to follow the same rut• Do not forget beginner’s mind even if it is a familiar work.
• Use tooling as specified• Do not drastically change parameters at once, such as beam optics parameters.
• Change them step by step while checking.

2021/2/8

B2GM

30

Luminosity profile for 2021 runs
• The luminosity profile was re-evaluated based on the results of 2020c and following
the strategy for 2021 runs.
• Assumptions for revaluating luminosity projection -1• Beam current  Key point
Improvement factors

Higher risk ofcollimator damage
and QCS quench

Remove carbon
collimator

Relax BG limit
Vacuumscrubbing(not so drastic)

Anxiety factors~1.6A
Wider collimator
gap

Higher total beam
currents with large
number of bunches
Lower bunch
currents for the same
total current
Relax beam-beameffect2021/2/8

Lower impedanceWider physicalapertureLong
lifetime
Improve injection
efficiency~1.5 A

Relax TMCI limit~1mA/bunch ~ 1.5 A

Frequent Belle aborts

Strong beam-beam effectat high currents• Beam-size blow up• Bema-size oscillation• To be studied

Longer dead time

No experience over 1 A

Injection beam
Stable 2 bunch inj. at~25Hz?

Stable high injection
efficiency?

• Considering these, it will be reasonable to assume thatthe beam current should be increased gradually, andthe maximum beam current with 1565 bunches is1.1~1.2 A (0.7~0.8 mA/bunch) for 2021a and b runs.
B2GM

31

Luminosity profile for 2021 runs
• Assumptions for revaluating luminosity projection -2• Specific luminosity

Y. Funakoshi• Same level to 2020b run• Expected to be improved gradually by ~10%?

• Others• The luminosity used for the calculation of Int.
Luminosity is 0.65 times of the peak luminosity,
which has been assumed to be 0.7 so far.
• Low reproducibility after run break• More tuning time will be required at high currents• Aging run before physics run, for example• But, no Linac study after maintenance day• Start physics run from night of the day• Physics run for 28 days per month basically. But,
• First week after starting run has no physics run (4 days physics run between 2/16〜2/28.)• Move to 1565 bunches from 4/1.

• The Int. luminosity includes that during the off-resonance run.
• ~1 week?

• Reduction in dP/dI ~ 60% at 6000 Ah.
• No long-term break• No trouble in collimators and other hardware (~1 week break in the case)2021/2/8• No intervene by COVID-19

B2GM

32

Long-term operation planPrevious plan (Revised based on the results until Phase-2) (2019)
Peak luminosity 8E35 cm-2s-1 in ~2026
Integrated luminosity 50 ab-1 in ~2028
by*= 0.3 mm in 2021
PXD exchange in 2021~2022
RF full upgrade (4 stations) in 2024
Max. beam currents: LER 3.6 A, HER 2.6
A (2500 bunches) in 2026
• Basically, 8 moths’ operation per year.
•
•
•
•
•
•

[Investment in equipment]• Full-scale RF-power upgrade (add 4
stations)• Beam collimator upgrade• Linac upgrade• Belle II upgrade
2021/2/8

B2GM

33

Long-term operation plan
Original plan (~2018)• Peak luminosity 8E35 cm-2s-1 in ~2025• Integrated luminosity 50 ab-1 in ~2027• PXD exchange in 2020~2021• RF full upgrade (4 stations) in ~2023• Max. beam currents: LER 3.6 A, HER
2.6 A (2500 bunches)• Basically, 8 moths’ operation per year.
Investment in equipment• Full-scale RF-power upgrade (4stations)• Beam collimator upgrade• Linac upgrade• Belle II upgrade
2021/2/8

B2GM

34

2021 and long-term operation plans• Comparison of luminosity profiles in the revised 2021 plan and the long-term plan
Min. βy* [mm](1565)
(978)

(978)

Int. L [fb-1] (Delivered)Lp [x1034 cm-2s-1](978)(1565)(978)

Lpx0.65 (2021a~) (978)From 2019c(1565)(978)

From 2019c run

Max. I [A]
(978)

(

Beam dose [Ah](1565)
(978)

(978)

Lsp x βy* [E31 mA2]

 Long-term
Plan Revised
2021 Plan(base)
 Result until
2020c(1565)(978)
Result in 2020b

Note: Constant Lp
was assumed
even for ib+*ib- >0.6 [mA2]

2021/2/4

MDI meeting352021 and long-term operation plan
• The revised luminosity
profile for 2021 runs is far
from that for the present
long-term one.

From 2019c run
• The peak and Int.
luminosities at the end of2021 are almost a half or
one third of original plan.

• Main Reasons:• Larger βy*2021/2/4

• Similar total beam current,
but lower bunch current.

MDI meeting

Long-term Plan
Revised 2021 Plan(base)
Result until 2020c• The specific luminosities
are almost the same.

36

2021 and long-term operation plan
• What to do tocatch up with thelong-term plan

• What to be improved
IssuesBackground(Storage)

Squeeze βy*

Increase total
beam current

Increasebunch current

Background(inj.)

Vacuumpressure

~2021

2022~

2026~

Vacuum scrubbing (not so drastic)
QCS beam pipe remodeling

Physical
aperture (QCS)

Add shielding

Collimator(Phys. aperture,
Impedance

Relocation, Optics optimization
Remodeling (low impedance, robust)

Beam lifetime
Dynamic
apertureBeamInstability
Beam size
blowup

Improve Spe.
Luminosity

Causes• How to improve (some possible measures)

Inj. efficiency(rate, stability)

Rotatable Sx, Perfect match

QCS remodeling?

Beam-beameffectUnderstanding of the mechanism (Chromatic coupling)?
Improvement in optics measurement and correction

Inj. quality(emittance,stability)

Understanding the reasons of low efficiency (especially on HER)FB system in BT and Linac (orbit, energy)

Inj. Charge(2unch Inj.)

Establishment of stable 2 bunch injection
Stable operation of RF gun• Relaxation of the background limit should raise the limit of beam currents, although the actual effectshould be examined in the next 2021a run.
2021/2/4
MDI meeting37

Long-term operation plan
• Major reasons for the update:• Issues in the previous operation plan
• Increase in the running cost (utility cost )• Challenges found in the initial operations (〜2020a) ：(a) Strong beam-beam effects in high bunch-current region(b) Narrow physical aperture in the QCS(c) High background in Belle II• Small dynamic aperture in the high bunch-current region with small βy* (~0.3mm), which had been recognized already as an issue in the design phase.
• Even if the design beam currents are realized after the full-scale RF upgrade, but
βy* is limited to 0.5 mm, the peak luminosity will be ~4E35 cm-2 s-1 at most.
• More utility cost will be required to operate with these beam currents.
• Even if we can operate for 7 months per year, after making various efforts, it will be2032~2033 before achieving the integrated luminosity of 50 ab-1.

Update2021/2/8

B2GM

38

Long-term operation plan
• Key points of update(1) Aim at an ecological operation reducing running cost, i.e., beam currents, asmuch as possible.
••

Put the priority on the integrated luminosity, rather than the peak luminosity.
Realize an integrated luminosity of ~50 ab-1 within a reasonable time period not so
different from the original plan.

(2) Modify the IR, especially upgrade QCS and its beam pipes• Relocation of magnets: Make it possible to squeeze βy* to 0.3 mm, mitigate thebeam-beam effect in the high bunch-current region•

Enlargement of QCS beam pipes: Protect QCS, and reduce the background.

(3) Retain the option to upgrade the RF power at the minimum level.
•

Store beam currents of LER 2.8 A and HER 2.0 A stably.
•

Even without an upgrade, beam currents of LER 2.5 A and HER1.8A will be possible.

(4) Investment of equipment for the upgrade of Linac, Belle II and beam collimatorsof MR are essential and the same as before for stable and high-efficiency
operation.
2021/2/8

B2GM

39

Long-term operation plan
• Major upgrades (Investment of equipment)• Belle II
•
•
•
•
•
•

Preparation of SVD spare.
Replacement of CDC FEE and readout circuits
Replacement of PID (MCP-PMT) in Barrel
Replacement of PID (HAPD) in ARICH
Replacement of a part of ECL
Modification of the IP beam pipe

• Linac••••Development of collimators and high-precision supports
Installation of ECS (Energy Compression System) for e- line
Addition of pulsed magnets
Replacement of a thousand capacitors containing PCBs

• MR
•
•
•
•
2021/2/8

Modification of the IR, including QCS, its cryostat, beam pipes inside, and RVC
Upgrade of RF power stations and the control system
Development of robust beam collimators
Reinforcement of a radiation shield around the IR and collimators
B2GM

40

Long-term operation plan
• BPAC Report (2020/6)• Based on the experience in operating SuperKEKB, the machine team has
been developing ideas that could achieve the physics goal of the Belle IIexperiment with lower consumption of electricity . The committee
understands that such an operation scenario over the next ten years waspresented in the KEK submission to the MEXT Roadmap selection
process, and finds this development timely and very attractive.
Implementing such a plan requires an upgrade of the machine anddetector. The BPAC strongly encourages a close collaboration between
SuperKEKB and Belle II to further explore various ideas and conduct thenecessary research and development work. Implementation of thenecessary upgrade should then follow after positive evaluation oftechnical designs by the relevant committees. The BPAC is looking
forward to hearing the progress in future meetings and strongly hopes fora positive outcome from the MEXT Roadmap selection.

2021/2/8

B2GM

41

Long-term operation plan
• KEKB Review Report (Long-term plan part) -1 (2020/7)• R7.2: Over the next year or so, perform beam measurements todetermine if the proposed QCS upgrades with larger apertures are
absolutely required to get to the design luminosity or, e.g., to half thedesign luminosity.
• R7.6: Determine which technical studies (essential beam studies and
QCS coil parameter studies) need to be carried out now, before adecision can be made, within about 2 years, on starting construction of
new QCS quadrupoles.
• R7.7: Determine the technical staffing and accelerator experts needed toconstruct the required hardware upgrades and examine if new technicalstaff will need to be trained or hired to design and execute these
upgrades.
• R7.9: Present a detailed SuperKEKB upgrade plan with underlying
reasoning and data at the next ARC meeting.
2021/2/8

B2GM

42

Long-term operation plan
• KEKB Review Report (Long-term plan part) -2 (2020/7)• R7.8: Evaluate a backup plan to simply increase the luminosity with theexisting hardware to about 2-3x1035 cm-2s-1 (with small upgrades but
without major upgrades and the associated long installation downtimes
and serious recommissioning) and then integrate luminosity for about 1012 years at 7-8 months per year to obtain an integrated luminosity of 50
ab-1 by 2032-2034.
• Detailed long-term upgrade plans should be finally decided once full
performance with those upgrades is predicted within a quantitative
performance model. This makes sure that the long-term quadrupole
aperture is chosen wide enough, background sources and paths areunderstood, lower beam lifetime can be handled, impedance stays undercontrol, and the collimator system is adequate.

2021/2/8

B2GM

43

Long-term operation plan meeting• Four meetings have been held so far (~2021/2/4)• The first meeting on 2020/8/21• The process so far [Y. Suetsugu]• Present status of QCS update project [N. Ohuchi]• Future plan of this meeting [H. Koiso, Chair]• The second meeting on 2020/9/3• Summary of the first meeting [H. Koiso]• Examination status of the optics for QCS upgrade [A. Morita]• Crab waist, dynamic aperture and beam lifetime [K. Oide]• The third meeting on 2020/9/26• Effect of IR Model V-20-20A (large physical aperture in QC1) on the beam optics [H.
Sugimoto]• Examination of QC0P (Permanent magnet) [A. Morita]• Luminosity and lifetime (update) [K. Oide]• Effect of the enlarged physical aperture in QC1P on MDI mechanical design andbackground [H. Nakayama]• On flange at the top of QCS cryostat [N. Ohuchi]• Dependence of the injection efficiencyB2GM
on βy* [Y. Funakoshi]
2021/2/8

44

Long-term operation plan meeting• The fourth meeting on 2021/1/22• Progress report on QCS of upgrade project [N. Ohuchi]• LER dynamic aperture and luminosity (update) [K. Oide]• Status, issues and future plan of BT and Linac from the view point of beamcommissioning [N. Iida]• Middle and long-term outlook on injection efficiency and luminosity [Y. Funakoshi]• The fifth meeting on 2021/2/17 (planned)• Long-term strategy of BT [M. Tawada]• Long-term strategy of Linac [K. Furukawa]• Long-term strategy of beam collimators [T. Ishibashi and S. Terui]• We have been also discussing about IR upgrade on other meetings, such as IRtechnical meeting (hosted by N. Ohuchi) and MDI meeting (hosted by H.
Nakayama).

2021/2/8

B2GM

45

Overall schedule
2021/1/24

SuperKEKB⻑期プラン
2020年度

項目
MR

備考
0.6mm

βy*絞り込み

2021年度運転

休運転

2022年度P X D 交換

運転

2023年度
運転

休

0.5mm

運転

2024年度運転

休運転

2025年度運転

休運転

2026年度運転

IR(QCS)改造

2027年度
運転

休

運転

0.3mm

クラブウェスト効果検証(高バンチ電流)
バックグラウンド測定・調査・低減
ビームライフタイム調査・向上
ビームビーム効果原因調査・緩和
入射効率調査・向上
コリメータインピーダンス測定・評価
HER synchrotron入射検証
軌道コントロール精度向上
回転六極の効果検証
回転六極ノブ化
RF制御(LLRF)デジタル化

少しづつ進行中HERコリメータ改良(精度向上)

少しづつ進行中

LERコリメータ改良(LowZ, 低Imp.)(LER)キッカー改良(波形整形)
ビームハロー計測

計画中

RF増強
新型コリメータ(e-ビーム型、RF型)
RF水冷塔補強(蒸気冷却系)

少しづつ進行中

RFクライストロン電源更新
RF空洞減衰器更新電磁石フロースイッチ類更新

少しづつ進行中

電磁石電源更新
電源棟屋根・外壁修理
ヘリウム冷凍機機器類更新

少しづつ進行中

超伝導低温真空実験棟関連
IR
(QCS)

光学モデルの検討(実用解はあるか)
IR改造の範囲検討
Belle II測定器との取り合い検討
QCS技術的問題の洗い出し(製作性、超伝導線、アラインメント)
QCS人的問題の検討
QCS接続方法検討
IPベローズ検討
QCS改造
改造後コミッショニングプラン検討
ビームエミッタンス爆発原因調査・対策

BT

フィードバック(エネルギー、軌道)整備

進行中

スクリーンモニタOTR化

進行中

BPM精度向上、高速化
ショットID管理化
BT電磁石電源更新
ECS電源、電磁石更新

DR
Linac

オプティクス理解
パルス電磁石増強

進行中

J-arc電源改造

進行中

パルス電磁石モニター整備
光ファイバロスモニタPV化
PCB対策
短期運転プラン(コミッショニング)性能(performance)モデルの構築
ベースプランの評価

コミッショニング関係(ソフトウェア)

2021/2/8

ハードウェア関係
IR(QCS)改造関係

B2GM

46

2021/2/8

B2GM

K. Oide 2021/1/22

47