Near- and Long-term operation plans
Y. Suetsugu
KEK Accelerator laboratory

2020/7/15

KEKB Review 2020

1

Contents
1) Near-term plan (until March, 2021)• Progress after the last Review (July 8, 2019)• Brief summary of results until 2020b run• Near-term plan and luminosity projection
2) Long-term plan (coming next 10 years)• Proposal to MEXT Roadmap2020• Update of operation plan•••
2020/7/15

Reasons
Key points

Long-term plan and luminosity projection
KEKB Review 20202

Progress after the last review• Recommendations in the last KEKB Review in relation tooperation plan••

The ARC endorses the proposed operational goals for Phase 3.1,
toward y* of 0.64 mm, 2 kAh, 200/fb, 3x1034cm-2s-1 by summer
2020. (R2.1)
By autumn 2019, evaluate different operating scenarios, select theone with the best risk-reward ratio, and establish a detailed
commissioning plan for accelerator and background studies.

• After the review, we discussed the commissioning scenario
to realize the above goals.
•

It was finally decided that 2019 Autumn run (2019c) was mainly
focused on the machine studies, especially to squeeze y* to 1 mm
(or less) in order to improve luminosity, to investigate the sources ofbeam background, and to further study the causes of beam-beameffects.

• Major works during 2019 summer shutdown••

2020/7/15

Replacement of IR bellows and BPMs.
Improvement in the beam-abort system to abort beams as fast as
possible for safe operation at high-beam currents.
KEKB Review 20203

Progress after the last review

Operation plan: near term Presented at BPAC (2019/10/2)• Expected luminosities in Base plan
I [A]Beam dose [Ah]P x I [Pa A](Result in
2019b)

2000

y* [mm]

Lsp x y* [x1031 cm-1s-1]
vs Ib+xIb-[mA2]

Lp [x1034 cm-2s-1]

Int. L [fb-1]

3.0

200

1.0

Assumptions:
Similar background level as 2019b, with slightly improvement by 50%.
Similar beam-beam effects as 2019b, with slightly improvement by 20%.
Beam background is independent of y*.
2020/7/15

KEKB Review 2020

4

Progress after the last review• Main results in 2019c
I [A]Beam dose [Ah]P x I [Pa A](Result in
2019b)

2000

y* [mm]

Lsp x y* [x1031 cm-1s-1]
vs Ib+xIb-[mA2]

Lp [x1034 cm-2s-1]
3.0

Int. L [fb-1]

200

1.1
1.0

•

During 2019c, we succeeded to squeeze y* to 1 mm as planned, anda peak luminosity of 1.14x1034cm-2s-1 (w/ Belle II) was achieved(1.88x1034cm-2s-1 w/o Belle II).
••

2020/7/15

Background was well controlled thanks to collimator tunings.
On the other hand, the beam-size blow up due to beam-beam effects
was still remained, and the specific luminosity was less than expected.
KEKB Review 2020

5

Progress after the last review• After 2019c, we revised the operation plan until July 2020
(2020a and b) based on the results of 2019c.
•••

The 2020a and b were decided to be basically dedicated to physics
run, in parallel with various studies to improve the performance.
• Crab-waist scheme for LER was prepared.
The luminosity projection was also re-evaluated based on theproven beam-beam effect as a base plan, and explained inSuperKEKB workshop, January, and proposed in BPAC, February.
• Unfortunately, the operation period was limited to ~5.4 months
due to lack of budget.
The goal values were, as a result, somewhat smaller than thoserecommended by ARC (July 2019), but they were more realistic.

• In January, we held the SuperKEKB workshop at KEK, anddiscussed the results of 2019c and the plan.
• Major works during 2019 winter shutdown••
2020/7/15

Installation of a vertical-type collimator into LER to further reducebeam background.
Preparation of the crab-waist scheme for LER
KEKB Review 2020

6

Progress after the last review• Near term luminosity projection (~2020 June)(1) Base (conservative) plan Presented at BPAC (2020/2/10)
Goals at the last review (2019 July)

I [A] ( 𝐼+ 𝐼− )(1576 bunches)

0.7→ ~0.8

Cal., Assumption
And explained at SuperKEKB workshop (2020/1/31) ■ Result in 2019c

Beam dose [Ah]P x I [Pa A]
BG from storage beam

(1576 bunches)●

Lsp x y* [x1031 cm-1s-1] vs
Ib+xIb-[mA2](1576 bunches)(1576 bunches)

2000→ ~1800(Result in
2019b)(Result in
2019c)

y* [mm]

Lp [x1034 cm-2s-1]

Int. L [fb-1]

B-B param. (HER)(1576 bunches)(1576 bunches)(1576 bunches)~0.02

3.0→ 2.2~200→ ~100

0.64→ 1.0

2020/7/15(Result in
2019b)KEKB Review 2020

7

Brief summary of results until 2020b• Main results in 2020a, b•

Details are presented by Ohnishi-san.

Goals at BPAC (2020 Feb.)

I [A] ( 𝐼+ 𝐼− )(783bunch)(978bunch)

~0.8
~0.69

P x I [Pa A]
Beam dose [Ah]BG from storage beam

(783bunch)(978bunch)(783bunch)(978bunch)

~1800
~1180

●

Cal., Assumption■ Result in 2019c, 2020a, b

Lsp x y* [x1031 cm-1s-1] vs
Ib+xIb-[mA2]
2020/6/20-6/21
CW L80% H40%
978 bunches
by=1mm(Result in
2019b)(Result in
2019c)

y* [mm]

Lp [x1034 cm-2s-1]

Int. L [fb-1](783bunch)(978bunch)

~100
~67

2.2
~2.4
1.0

2020/7/15(from 2019c)

B-B param. (HER)
2020/6/20-6/21
CW L80% H40%
978 bunches
by=1mm

~0.025~0.02(Result in
2019b)

0.8

KEKB Review 2020

8

Brief summary of results until 2020b• Results until 2020b

Goals at BPAC (2020 Feb.)y* [mm]

Lp [x1034 cm-2s-1]

Lsp x y* [x1031 cm-1s-1] vs
Ib+xIb-[mA2](783bunch)(978bunch)

2020/6/20-6/21
CW L80% H40%
978 bunches
by=1mm

2.2 ~2.4
1.0

0.8(Result in
2019b)• y* was kept at 1 mm••

Stable physics run with y* = 1 mm was achieved.
y* = 0.8 mm was tried finally.

•

Mainly thanks to the crab waist collision scheme in both LER
and HER.

• Peak luminosity increased almost as expected.

• Specific luminosity vs bunch-current products was almost as
expected.
•

2020/7/15•

Specific luminosity was kept at high value at high bunchcurrents thanks to the crab waist collision scheme.
But still affected from beam-beam effect.
KEKB Review 2020

9

Brief summary of results until 2020b• Results until 2020bInt. L [fb-1]

Goals at the last BPAC (2020 Feb.)

I [A] ( 𝐼+ 𝐼− )(783bunch)(978bunch)

~100

~67

~0.8
~0.69

Beam dose [Ah](783bunch)(978bunch)

~1800

~1180

(from 2019c)• Int. luminosity was less than expected.
•••

More machine-study time than planned, such as HER crab waist
scheme. But it contributed to increase peak luminosity.
More down time than expected due to machine troubles, Belle IIdetector troubles, lots of beam aborts, and so on.

As a result, the efficiency was less than 70% (50~60%).

• Beam currents were less than expected.
••
2020/7/15•

Operation with smaller number of bunches, and then difficulty inbeam injection at high bunch currents due to beam-beam effect,
short beam lifetime.
Hardware (vacuum) problem at high-bunch currents in HER.

Due to low beam currents and shorter running time, the beam dose
was also less than expected consequently.
KEKB Review 2020

10

Near-term plan and luminosity projection• 2020c will start from Oct. 19, after summer shutdown.
•

Linac will start from Sept. 28 prior to that for the tuning (BT, DR)
and PF injection.

• 2020c will stop Dec.18.
• 180 shifts (60 days) in total•••~112 shifts for physics run~64 shifts for machine study and tuning
4 shifts for regular maintenances, and 8 shifts for Linac studies
Draft of 2020c machine time
2020
October
28 1

BT Study

November

11

21

1

11

December
21

1

11

21

Linac, Dr, BT Study (Dump mode)

MR

19

28

11

25

9

18

Owl shiftDay shift
Swing shft
Machine study
Physics run
Linac study
MaintenanceTotal

2020/7/15

56
112
8
4
180

Shifts (includes startup tuning)
Shifts
Shifts
Shifts
ShiftsKEKB Review 202011

Near-term plan and luminosity projection• 2020c commissioning plan was discussed based on the
results until 2020b.
• Main theme of 2020c is to squeeze y* as planned.
••

Operation with y* = 1 mm was achieved in 2020b.
Goal is y* ~ 0.6 mm.

••

We need some time to calm down and think the results of studies.
Basically, owl shifts and weekends will be assigned to physics run.

• Machine studies will be scheduled appropriately in parallelwith physics run, similarly to 2020b.
Draft of 2020c run plan
2020
October
28 1

BT Study

November

11

21

1

11

December
21

1

11

21

Linac, Dr, BT Study (Dump mode)

MR

19

28

11

 y*=1.0 mm

 y*=0.8 mm

25

9

18

Owl shiftDay shift
Swing shft
Machine study
Physics run
Linac study
MaintenanceTotal

2020/7/15

56
112
8
4
180

Shifts (includes startup tuning)
Shifts
Shifts
Shifts
ShiftsKEKB Review 2020

 y*=0.7 mm

 y*=0.6 mm

12Near-term plan and luminosity projection• Study items•••

Main item is to squeeze y*. (y* = 0.8 mm was tried during 2020b).
Studies to realize stable operation with each y*, accordingly.
• Injection, background, etc.
Beam-beam and optics studies for future runs
• The crab waist collision scheme will be kept in 2020c.
Draft of 2020c run plan
2020
October
28 1

BT Study

November

11

21

1

11

December
21

1

11

21

Linac, Dr, BT Study (Dump mode)

MR

19

28

11

 y*=1.0 mm

 y*=0.8 mm

25

18

9

Owl shiftDay shift
Swing shft
Machine study
Physics run
Linac study
Maintenance
Total

56
112
8
4
180

Shifts (includes startup tuning)
Shifts
Shifts
Shifts
ShiftsStart up
- Vacuum scrubbing (40 Ah)- Recovery to 2020b condition- Injection study
2020/7/15

 y*=0.7 mm- Squeezing y* to 0.8 mm, 0.7 mm, 0.6 mm- Injection study/tuning- Background study- Beam-beam / optics study- Other hardware/software studies
KEKB Review 2020

 y*=0.6 mm- Machin studies ifnecessary- Optics study

13

Near-term plan and luminosity projection• Major works planned during this summer shutdown• Hardware• Installation of one vertical-type beam collimator in LER•

D03_V1•

Change the material from Tantalum to Carbon• Replacement of D06_V1 collimator head
• Replacement of flux concentrator (e+) and pulsed bending
magnets in Linac• Software• Preparation of various tuning tools•••

For example, tools to control rotatable sextupole magnets inphase.
Preparation for synchrotron injection
Improvement in collision feed-back system• Others• Regular maintenances, only possible in long shutdown.

→Improvement in background, injection efficiency andmachine tunability are expected to some extent.
2020/7/15

KEKB Review 202014

Near-term plan and luminosity projection• Luminosity projection was re-evaluated.
••

Int. Luminosity etc. were adjusted to the results of 2020b.
Similar specific luminosities and beam-beam parameters wereassumed as a base plan (with crab-waist).

• Until 2020c( 𝐼+ 𝐼− )I [A](978 bunches)●Cal., Assumption ■ Result in 2019c, 2020a, b ● Original plan in 2019a,b

Beam dose [Ah]P x I [Pa A]
BG from storage beam

(978 bunches)(978 bunches)~1700

Lp [x1034 cm-2s-1](978 bunches)(978 bunches)(Result in
2019b)~0.74

y* [mm]

Lsp x y* [x1031 cm-1s-1] vs
Ib+xIb-[mA2]

Int. L [fb-1](978 bunches)

B-B param. (HER)(978 bunches)

~0.03
~4.0

~110
(Result in
2019b)

0.6
2020/7/15

KEKB Review 2020

15

Near-term plan and luminosity projection• Until 2021a• We assumed that it is dedicated to physics run, and that 6.5~ 5.5 months operation this year (depends on the budget,
as you know.).
Cal., Assumption Result in 2019c, 2020a, b Original plan in 2019a,b■●

I [A] ( 𝐼+ 𝐼− )y* [mm]●Int. L [fb-1]

Lp [x1034 cm-2s-1](978 bunches)(978 bunches)(978 bunches)

~6

~240

~0.9

0.6

• In summary,Parameters

Base plan until 2020c
Base plan until 2021a(Depend on operation time)
2020/7/15

Int. L [fb-1]

Lp [E34]

Imax [A] (ave.)y* [mm]

~110

~4

0.74

0.6

240~140

6.5~4.5

0.9~0.75

0.6

KEKB Review 202016

Summary-1 (Near-term)• 2020b has been operated successfully with y* = 1 mm andadopting crab-waist collision scheme in both LER and HER.
• 2020c will start from Oct. 19, and will stop on Dec. 18.
• 180 shifts (60 days) in total• Machine study time will be scheduled appropriately inparallel with physics run.
• Main study item is to squeeze y*, down to ~ 0.6 mm (goal).
• Studies to realize stable operation with these y*, accordingly.
•

Injection, background, etc.

• Studies important to predict the future operation.

• Luminosity projection of 2020c (and 2021a) is re-evaluatedbased on the results until 2020a and b.
Parameters

Base plan until 2020c
Base plan until 2021a*(Depend on operation time)

Int. L [fb-1]

Lp [E34]

Imax [A] (ave.)y* [mm]

~110

~4

0.74

0.6

240~140

6.5~4.5

0.9~0.75

0.6*Here we assumed 6.5 ~ 5.5 months’ operation this year.
2020/7/15

KEKB Review 202017

Contents
1) Near-term plan (until March, 2021)• Progress after the last Review (July 8, 2019)• Brief summary of results until 2020b run• Near-term plan and luminosity projection
2) Long-term plan (coming next 10 years)• Proposal to MEXT Roadmap2020• Update of operation plan•••
2020/7/15

Reasons
Key points

Long-term luminosity projection
KEKB Review 2020

18

Proposal to MEXT Roadmap2020• KEK submitted 10 year SuperKEKB project to the SCJ
Master plan 2020. The project was ranked as one of the 31
most important projects.
• The next step is the MEXT Roadmap2020 selection. The
Roadmap2020 is a fundamental plan of the MEXT for thepromotion of large-scale projects in academic research.
• Revised every three years.

• Now we are making the SuperKEKB Roadmap2020, i.e., thebudget and operation plan for the coming 10 years.
• The proposal was already submitted to the MEXT in February.
The hearing is planned in August.

• In this roadmap, we proposed to update the present
operation plan (2019) considering the actual situation andthe results obtained so far.

• This is not such a large change as a successive project, butrather changes towards a more realistic plan.

• Here the reasons and key points in the update are explained.
2020/6/29

BPAC 2020 0629

19

Update of operation plan and its reasons• Present plan
• Proposed at the BPAC, Feb., 2020
• Updated based on the results after Phase-2

Int. luminosity [ab-1]

Peak luminosity [x1035 cm-2s-1]

Proposed at the last BPAC

RF
[full]

PXD

2020/6/29

BPAC 2020 0629

• Peak luminosity 8E35 cm-2s-1 in~2026• Integrated luminosity 50 ab-1 in ~2028• y*=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 months operation per year.
[Investment in equipment]• Full-scale RF-power upgrade (add 4
stations)• Beam collimator upgrade• Linac upgrade• Belle II upgrade

20

Update of operation plan and its reasons• Updated plan

Int. luminosity [ab-1]

Peak luminosity [x1035 cm-2s-1]• Proposed in Roadmap 2020

RF[partial]

IR (QCS*)

PXD(Tuning)*QCS:
Superconducting final focusing quadrupole magnet• 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 in 2026
• y*=0.3 mm in 2026 after IR upgrade,and ~0.5 mm before that• Max. beam currents: LER 2.8 A, HER
2.0 A (1761 bunches) in 2027
• Basically, 8 months operation per year.
[Investment in equipment]• IR (QCS and its beam pipes etc.)• Partial RF-power upgrade (2 stations)• Beam collimator upgrade• Linac upgrade• Belle II upgrade• Main motivations are explained below.
2020/6/29

BPAC 2020 0629

21

Update of operation plan and its reasons• Main reasons:(1) Increase in the running cost (utility cost )(2) Challenges found in the initial operations (～2020b) ：(a) Strong beam-beam effects in high bunch-current region(b) Narrow physical aperture in the QCS(c) High background in Belle II(3) Small dynamic aperture in the high bunch-current region
with small y* (~0.3 mm), which had been recognizedalready as an issue in the design phase.

2020/6/29

BPAC 2020 0629

22

Update of operation plan and its reasons• Reason-1(1) Increase in the running cost (utility cost )• If we want to run with the max. beam currents in the original
design (LER 3.6A, HER 2.6A), approximately 1.6 times theelectric power (i.e., running cost) is required compared to thatused at present (0.5 ~ 1 A) .
• If the operation budget does NOT drastically increase, and theelectricity unit cost remains at a similar level, the operation
period per year will be strictly limited.
• As a result, it takes a long time to achieve the integratedluminosity goal, and the total running cost will further increasein proportion.
→ More effective (ecological), that is, better collision performancewith lower beam currents is required to achieve the goal in areasonable time period.
2020/6/29

BPAC 2020 0629

23

Update of operation plan and its reasons• Reason-2(2) Challenges found in the initial operations (～2020b) ：(a) Strong beam-beam effects in high bunch-current region•

In high bunch-current region (ib+ x ib->～0.2 mA2), the specific luminosity
is lower than expected owing to the vertical-beam size blowup due tothe beam-beam effect, and the beam-beam parameter is also lower.
• Main reason is thought to be chromatic x-y coupling at the IP(Interaction Point), but this is not yet confirmed.
• Crab waist collision
scheme and utilizing
skew sextupole magnets
are very promisingsolutions at present, but
their effectiveness is not
yet confirmed up to thefinal goal of y*= 0.3 mm.
2020/6/29

Specific luminosity vs. bunch-current products

y* = 1 mm

BPAC 2020 0629

24

Update of operation plan and its reasons• Reason-2(2) Challenges found in the initial operations (～2020b) ：(a) Strong beam-beam effects in the high bunch-current region• A recent simulation indicated that one promising method to mitigate theeffect will be the modification of QCS to avoid interference between thequadrupole magnetic field and the Belle II solenoid field for the LER.
QCS magnets• Further study is on-going.
Solenoid field (Bz) and integrated Bz in QCS

2020/6/29

BPAC 2020 0629

25

Update of operation plan and its reasons• Reason-3(2) Challenges found in the initial operations (～2020b) ：(b) Narrow physical aperture in the QCS• Quenches of QCS caused by hits from unstable beams have been
observed.
• In the worst case, this may result in damage of the QCS coils.
• At present, beam collimators are
effectively preventing this by closing theBeam size in QCS
collimators to narrower physical apertures
than the beam pipe in the QCS.
• However, if we wish to squeeze y* to lessthan 0.5 mm, y function at QCS will
become even larger, and it will be difficult
to protect the QCS by using collimators.
• The narrower the beam collimators,
the shorter the beam lifetime, and thehigher the risk of damage ofcollimators due to beam loss.
2020/6/29

BPAC 2020 0629

QC2 QC1QC1 QC2

26

Update of operation plan and its reasons• Reason-4(2) Challenges found in the initial operations (～2020b) ：(c) High background in Belle II• At present, the background in Belle II is larger than expected.
• One of main causes is hits from stored beams and/or injection beam
halo on the beam pipe in the QCS.
• The background also depends
Source points of background (reconstructed from
CDC track data) [H. Nakayama, SuperKEKB WS.]
on the vacuum pressure in thering and the quality of injection
beams.
• The background will become more
severe as y* is squeezed further.
• The y function at the QCS will
become large. And hence it will
be easier for the beam halo to
hit the beam pipe.

2020/6/29

BPAC 2020 0629

27

Update of operation plan and its reasons• Reason-5(3) Narrow dynamic aperture at high-bunch current at small y*• It was reported that the LER Touschek lifetime will be approximately
200s due to the narrow dynamic aperture at y* = 0.3 mm and thebeam-beam parameters ~0.09. (Designed lifetime is approximately
600 s)• This fact had been pointed out
around 2014, and simulation
studies have continued sincethen.
• The problem, however, has notbeen solved so far. Somemeasures should beconsidered to reduce y* further.

2020/6/29

BPAC 2020 0629

[Y. Ohnishi, 18th KEKB Review, 2014]28

Update of operation plan and its reasons• A possible scenario in the present situation -1• Even if the design beam currents of LER 3.6 A and HER 2.6 A are
realized (2185 bunches) after the full-scale RF upgrade, but y* islimited to 0.5 mm, the peak luminosity will be ~4E35 cm-2 s-1 at most.
• As described before, weneed more utility cost tooperate with these beam
currents. Even if we canoperate for 7 months per
RFyear, after making various[full]
efforts, it will be
PXD
2032~2033 before
achieving the integrated
luminosity of 50 ab-1.

2020/6/29

BPAC 2020 0629

29

Update of operation plan and its reasons• A possible scenario in the present situation -2• If we have NO upgrade of RF system (i. e. Max. LER 2.5 A /HER 1.8 A),
and y* is limited to 0.5 mm, the peak luminosity will be ~3E35 cm-2 s-1
at most.
• In this case, we have nolong-shutdown.
• Even if we assume 8months operation peryear, the integrated
luminosity goal of 50 ab-1
will be achieved in
2032~2033.

PXD

Update of present operation plan
2020/6/29

BPAC 2020 0629

30

Key points in the update(1) Aim at an ecological operation reducing running cost, i.e., beam
currents, as much as possible.
••

Put the priority on the integrated luminosity, rather than the peakluminosity.
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 y* to 0.3 mm,
mitigate the beam-beam effect in the high bunch-current region• Enlargement of QCS beam pipes: Protect QCS, and reducethe 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) Keep essential investment of equipment for the upgrade of Linac,
Belle II and beam collimators of MR as before for stable and highefficiency operation.
2020/6/29

BPAC 2020 0629

31

Key points in the update• Major hardware upgrades (Investment of equipment)• Belle II
•
•
•
•
•
•

Preparation of VXD 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

•
•
•
•

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•

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• Linac

• MR
•
•
•

2020/6/29

BPAC 2020 0629

32

Key points in the update• A rough time chart

2020/6/29

BPAC 2020 0629

33

Long-term luminosity projection• luminosity projection in the proposed update• After these upgrades, the stable operation at beam currents(LER 2.8A and HER 2.0A) with y*of 0.3 mm will be possible
after 2026. If the beam-beam parameters of 0.07~0.08 areachieved, the peak luminosity will be ~6E35 cm-2 s-1.
• If 8 months operation per year is realized, again after making
various efforts, the integrated luminosity of 50 ab-1 will beachieved in ~2030.

RF[partial]

IR (QCS)
PXD

0.3 mm(Tuning)(Tuning)
2020/6/29
2020/6/16

BPAC 2020 0629

34

Long-term luminosity projection• luminosity projection in the proposed update• These upgrades promote the achievement of the goal, 50 ab-1
in the coming 10 years.
• They also expand the options or flexibility in the operation,
and as a result, reduce the risk.
(RF full-upgrade in 2024, no IR upgrade)

2020/6/29

BPAC 2020 0629

(No RF full-upgrade, no IR upgrade)35

Summary-2 (Long-term)• MEXT SuperKEKB Roadmap 2020
• Deliver colliding beams to the experiment with a several tentimes higher luminosity than in the preceding KEKB project byusing the nano-beam collision scheme.
• Aim at an integrated luminosity of 50 ab-1 in coming 10 years.
• Proposed update of the operation plan:•••

Aim at ecological operation with high efficiency, and put priority
on integrated luminosity, rather than the peak luminosity.
Modify the IR, especially upgrade the QCS and its beam pipes,
to squeeze y* to 0.3 mm as designed, and then improve thecollision performance.
Investment of equipment, such as Linac upgrade, Belle II
upgrade, beam collimator upgrade, are planned as before,
which are essential for stable and efficient operation at highbeam currents.

• The plan is within the framework of MEXT Roadmap, but it ismore realistic considering the present situation and recent
experience.
2020/6/29

BPAC 2020 0629

36

Thank you for your attention.

2020/7/15

KEKB Review 202037

2020c run plan
• Major study items• Optics••

Squeezing y* down to 0.6 mm
Precise measurement and correction of optics parameters••

Two bunch injection
Synchrotron injection•

Beam collimator tuning•

Investigation of the cause•

Bunch spacing and number of bunches•

Effect of IP chromatic coupling on beam-beam blowup• Measurement of optics parameters at IP• Utilization of rotatable sextupole magnets (LER) and skew
sextupole magnets (HER)High bunch-current operation to check beam-beam effectCrab waist scheme• Injections• Beam background• Beam aborts• Fill patterns• Beam-beam••
2020/7/15

KEKB Review 202038

Updated luminosity projection (parameters)• Long term operation plan-1( 𝐼+ 𝐼− )2020/7/15

KEKB Review 202039

Updated luminosity projection (parameters)• Long term operation plan-2

2020/7/15

KEKB Review 202040

SuperKEKB Roadmap2020• Original plan (until 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’ MR operation per
year.
RF(full)

Investment in equipment• Beam collimator upgrade• Linac upgrade• Belle II upgrade• Full-scale RF-power upgrade (4stations)

PXD

http://www-superkekb.kek.jp/img/ProjectedLuminosity_v20190128.png

2020/7/15

KEKB Review 202041

Long-term luminosity projection• Note-2• It is clear that ahead of upgrade schedule of QCS/RF greatly
speed up the luminosity accumulation.

IR upgrade in 2026

IR upgrade in 2025

RFRF

[partial][partial]

IR (QCS)IR (QCS)PXD

PXD(Tuning)(Tuning)

2020/6/16

2020/7/15
2020/6/16

KEKB Review 2020

Belle II EB

42