SuperKEKB main-ring status
Gaku Mitsuka (KEK, Accelerator Laboratory)
on behalf of the SuperKEKB commissioning group
B2GM, 8 Feb. 2021

Outline• Target luminosity and operation schedule• Strategy for 2021a• Challenges for high-current beam operation• Readiness for the other major challenges• Summary2• 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 direc

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

2021 runs will be dedicated for luminosity production.
•• Major premisefor 2021
runs luminosity higher than BaBar’s 433 fb
Towards
integrated•• 2021 runs should be dedicated for the luminosity production.
(integrated
luminosity
at theend ofdata,
2020c
is 90
fb .)fb (final integrated lumin• Produce
new physicalresults fromenoughover
424.18operation
period2021
runsofisDecember,~6.4 months.
BaBar, NIM
A726 (2013)203)throughat least by
the endbefore the long shut•ofExpected-1-1Realize stable operation at a high luminosity.

[Y. Suetsugu, M. Tobiyama]

Present plan2020
4

FY2020Present plan (20th Oct.)

2021
4

FY2021

5

6

7

8

9

10

11

12

2021
1

2

3

2020b

2020c

2021a

~3M

~2M

~1.5M

5

6

7

8

9

10

2021b

Plan (not fixed)[MEXT Road Map]

-1

4/1

~3.1M

11

12

2022
1

2

7/5

12/23

~2.6M

~6.5M/y

3

2021c
10/7

Total

PXD exchange

Total~5.7M/y• 2021a run will start on 16 Feb.
• The ﬁrst week will be dedicated to vacuum scrubbing at only LER.
• HER operation is supposed to start on 24 Feb, upon how we get the SCC
safety certiﬁcate on time.

3

Strategy for 2021 run
First target is to achieve the peak luminosity ~2.4 x 1034 cm-2s-1.
It was realized in 2020b run:
- βy* = 1 mm, βx* = 80 mm(LER)/60 mm(HER)- Crab waist 80%(LER)/40%(HER)- 978 bunches in total of 700 mA
Start oﬀ 2021a with such a well-understood optics, i.e. same as 2020b
Important to establish stable beam-injection
Increase beam currents gradually at βy* = 1 mm with 1565 bunches
Relaxing the TOP BG threshold from 1.2 MHz to 5 MHz allows higher beam
currents, i.e. putting a priority on getting luminosity > reducing BGs.
Accordingly, the LER maximum beam current
can be extended to 1.6-1.8 A.
Other options
Squeeze βy* further than 0.8 mm
upon positive indication

•
•
•
•
•
•

[K. Kojima]
4

Challenges
High beam currents
Transverse-mode-coupling-instability (a.k.a. TMCI), occurred in 2020c,
resulted in the rather tight Ibunch threshold ~0.7 mA/bunch.

•

Beam size σy* blowup due to dipole motion (8 Dec. 2020)

σy* (LER)

1)

2)

3)

4)

5)

1) LER beam-beam blowup got tamed bydecreasing the HER current.
2) Beam size suddenly blowed up due todipole motion at ~0.73 mA/bunch.
3) BxB FB gain +12 dBm
4) The dipole motion was suppressed byincreasing BxB FB gain (0.81 mA/bunch).
Nevertheless visible beam size
(dominantly dipole motion) was still large.
5) σy* for single LER back to normal (<0.2 μm)

Nominal single σy*[Y. Ohnishi, M. Tobiyama, T. Ishibashi,
S. Terui, H. Koiso and many…]• Most likely TMCI was caused by high-frequency wake ﬁelds owing to
the carbon-head D06V1 and additional D03V1 collimators.
5

Observation of TMCI with σy* and νy
Beam size σy* blowup for each collimator setting (17 Dec. 2020)

2
σy* (LER)

1

3

5

Sideband

4

where σs is the bunch length, h = gg ∗ is the bunch power specfunction at the location
6 of the coupling impedance ZT , I theenergy and f0 the revolution frequency.
Very often the ‘kick factor’Note:! +∞of the carbon-headkick1factorkT (σs ) =dωZT (ω)h(ω,
σs )
D06V1
collimator
is
about
2π −∞
1. LER σy* increases as the LER beam current.
twice that of D03V1
This
the formula for[Y. Ohnishi] 2. Changing νy reduces σy*. is used instead of the impedance.
(GdﬁdLby gives
Ishibashi).
3.
4.
5.
6.

BxB FB gain adjusted.
D03V1 collimator opens (18:09-18:14, ±1 mm → ± 2 mm).
D03V1 collimator closes (18:16, ±2 mm → ±1 mm).
D06V1 collimator opens (18:22, ±1.95 mm → ±2.25 mm).

2πQs E/ef0
Ith = ".
βT kT (σs )[J. Gareyte, CERN-SL-2000-075]

Remark:6 the threshold found with the two-particle model w

The D06V1 collimator replacement(s)
2020a

2020b

tantalum (→damage)

2020c

2021a

carbon→TMCI

tantalum (re-used)• In 2020c we observed no unexpected pressure increase nor heating.
• But, as a counter eﬀect, the carbon-head collimator having large•

impedance caused the beam instability and resulted in the 0.7 mA/bunch threshold.
Replaced the carbon head again in Jan 2021 with the tantalum head(re-used), allowing higher beam current in 2021a
beam[T. Ishibashi, S. Terui]
5 mmbottom side jaw
beam

60 mm

top side jaw

7

D06V1 collimator alignment in Jan 2021

QT3FOP.1
D6V1 collimator

Z axisQTAFOP.1

Y axis (ring outward)
X axis(beam going)• Align the center of flanges on each side of the D06V1 collimator to lie
along a line connecting two Q-magnets
8

D06V1 collimator alignment in Jan 2021••

This is D02V1, NOT D06V1!

Note that these results do not assure thealignment of the collimator head w.r.t. Q-mag.
Both horizontal and vertical residuals are well
below 100 um.

D6V1_U_OUT : Collimator flange’s outer position directed to QT3FOP.1
D6V1_U_IN : Collimator flange’s inner position directed to QT3FOP.1
D6V1_D_OUT : Collimator flange’s outer position directed to QTAFOP.1
D6V1_D_IN : Collimator flange’s inner position directed to QTAFOP.1

Z

X

Z
Y（リング外向き）[R. Ueki, M. Masuzawa, T. Kawamoto]Alignment results and residuals from target values (14 Jan. 2021)

LocationΔy [mm]D6V1_U_OUT

0.05

D6V1_U_IN

0.057

D6V1_D_OUT

0.044

D6V1_D_IN

0.051

Average [mm](IN+OUT)/2
0.054
0.048
9

Δz [mm]-0.0770.1
0.095-0.053

Average [mm](IN+OUT)/2
0.012
0.021

Other collimator work in shutdown
In situ baking of D02V1 and D06V1 collimators (LER)• Reduction in the base pressure may suppress beam-gas scattering BGs.
Replacement of damaged D09V3 collimator jaws (HER)• KEKB type titanium jaw (Ti + Cu-coat, 40 mm long), possibly reduces BGs
Replacement of D12V1 collimator drive mechanism (HER)• Allows precise positioning
D09V3 head after removal (19 Jan. 2021)

10[K. Shibata]Challenges
High beam currents (cont’d)
Beam collimators will be stayed open in 2021 to enlarge the physicalaperture and reduce impedance.
Such a collimator setting will increase BGs and injection-induced
beam aborts (Belle aborts and CDC trips), furthermore bring a risk ofcollimators’ damage and QCS quench.

••

Beam injection (see also linac reports)
Establish stable and two-bunch injection at 25 Hz repetition rate
Based on the experience so far, the maximum beam current with 1565
bunches will be ~1.2 A (~0.7 mA/bunch) for 2021a+b.
[Y. Funakoshi]

•
•

11

Upgrade of Bucket Selection
2.3 LER 入射用バケットセレクション（位相変調あり）

2.2 節のように、ビーム入射頻度に応じて
The upgraded bucket selection
system offers
a T は変化するものの、上限値 Tが設けられている。一方で下限値として 40 ms も設けられており、これは光学計
degree of freedom in a choiceof injection buckets
算によって出射ビームのエミッタンスが十分に小さくなるための最低時間として得られている。そのため、ビー
owing to the RF-phase pulse-by-pulse
modulation
ム入射頻度が 25 Hz より高くなる場合、
DR 内で蓄積されるビームは 2 パルスとなり、タイミングの計算には蓄in the LINAC 3-5 sectors; 積されている RF バケットを避けて入射するという制限を加える必要がある。避ける範囲は入出射キッカー電磁
Enables two-pulses operation
at DR
石の出力電流波形で決まっており、波形の立ち上がりと立ち下がり時間にそれぞれ 100 ns を要し、さらにキッカー電流は常に
2 バンチ運転用の波形となっているた
Enables injections withunequalintervals
め、96 ns の波形の重なりがある。そのため、蓄積パルス
Injection rate can beを蹴り出さないように次のパルスの入射をするためにはchangedwithout
151
バケット（100 + 96 + 100/1.96）は入射できない領
2.2 LER 入射用バケットセレクション（位相変調なし）
closing
Beam Gate. 域となり、これを避けて入射する必要がある（Fig. 1）。
LER、HER ともに
493 µs 待つことで全ての入射タイミングが見つかるが、DR の入射バケットも考慮に入れ
96ns
Triggersystemstable.
る場合、5120 と 230の最小公倍数である
117760 becomes
とおり
store

max

RF-phase@LINAC(degree)••••のタイミング列が必要になるため、必ず入射できるタイ
ミングが見つかるまでに最大で 117760× 96.3 = 11.3 ms
待たなければならない。しかしながら、クライストロン>100ns電源の仕様で 50 Hz 運転でパルス間隔が 18 ∼ 22 ms が>100ns
動作保証範囲となっているため、実際には LER の入射バケットからタイミングを探し、その中で商用 AC 50 Hz
96ns
を基準として ±1 ms 以内に入るような DR の入射バケッ
トを見つけるという手法をとる。
この手法を用いれば、LER バケットに入射できる DR
バケットは LER バケット毎に 23 バケットあるため、どの DR バケットにも入射可能であれば、493 µs の待ち時
間で 23 個のうち 1 つの DR バケットを使った運転タイミングを見つけることができる。1 。この手法を利用する
Figure 1: The storage configuration of 2-bunch, 2-pulse at
ためには DR に入射する前に DR からの出射タイミング
Damping Ring.
をあらかじめ計算する必要がある。この計算のためにはDR 内でのビームの蓄積時間を知っておく必要があり、これを変数 “Tstore ”で定義し、インプットパラメータとつまり、バケット番号（n, n + 49）に蓄積されている
してタイミングを計算する。
場合（1 バンチ目のバケット番号, 2 バンチ目のバケット
基本的な方針としては同一パルス内で DR から蓄積
番号）、入射できるバケットは（n + 100, n + 149）からビームの出射と DR への入射が同時に行われることが効 （n + 130, n + 179）までの 31 バケット分に制限がかか
率のよい運転となるが、ビーム入射頻度が低いときにはる。LER の入射バケットを一つ決定したときに DR の入Tstore もそれに応じて長くなり、あらかじめ計算した出 射バケットの選択自由度は 23 あり、その中で遅延時間
射タイミングと商用 50 Hz にずれが生じてくる。という
2 ms の中に含まれるタイミングは 4 通りである。4 通りのも商用 50 Hz は「正確な」50 Hz ではなく、周波数偏のタイミングが 31 バケットの領域に必ず含まれるとは差が 0.2 Hz 程度であるため、最大蓄積時間 “Tmax ” を定限らないため、2.2 節の方法では入射できないパルスが生義して、一定時間経過したビームは出射するようにしてじてしまい、ビーム入射頻度を 25 Hz より増やしても結いる。Tmax は商用 50 Hz のゆらぎの測定結果に基づい
果的に非効率な状況が生じる。そこで 2 パルス運転ではて 200 ms と設定した [2]。このため、ビーム入射頻度がDR 出射後のビームが通る入射器後半の RF 位相をパル

1st pulse

QCS_FW_135(mRad/s)

Storage conﬁguration at DR

2nd pulse••

Test run taken on Dec 16, 2020

LER Current (mA)

ぶことでそれぞれのバンチ電流の均衡がとれるように入射する方法である。また、これらの両方を織り交ぜて入射を行う「Combined」モードや、各入射バケットに一度だけ入射を行う「OneCycle」モードなども用意しており、様々なビームスタディや営業運転を円滑に行えるよ
うにしている。
また、入射パルスの中に一度に 2 つのバンチを加速し、入射するという「2 バンチ運転」も SuperKEKB 加
速器では可能であり、この場合、同期タイミングが 96 ns
後に訪れることからバンチ間隔も 96 ns で生成できるような仕組みとなっている。
これらの方法によって選択された入射バケットや入射タイミングなどの情報は、その計算を行っている IOC から共有メモリ（reflective memory）を介して入射器のタ
イミングステーションでイベントジェネレータ（EVG）
により配信される [1]。

Phase is changed manually.

There is no significant influencein BG@IP.

The fruitful tests are carried out
in 2020ab and 2020c runs.
[H. Kaji, H. Sugimura]→ Feasibility is confirmed.
2021ab starts with the existing (no modulation) Bucket Selection system.
Will be switched to the new system once the MR operation goes stable.
12Beam abort diagnostics
Beam loss & injection-related beam aborts (Apr. - Dec. 2021)[H. Ikeda]

Owing to low current?

• Many injection-related aborts (H/Linj) especially on Nov at HER, investigation••

on-going by the injector group.
Non-injection aborts (H/Lloss) need another preparation, since it has caused
QCS quenches and collimator damages. Understanding beam-dust
scatterings is ongoing (simulation, LM timing measurements, etc.)
Injection-veto module will be applied to LM signals near collimators not tostop collimator and/or injection tunings.
13

RF system• Completed the replacement of the D11D SCC with a spare cavity in Jan 2021
• D11D SCC showed the cavity pressure increase on Oct. 2020 and has been••
上昇

detunedthrough 2020c.
追加真空ポンプ
No signiﬁcant
operation
Gate eﬀects
Valve (GV) of the D11D detuning
上流GV on beam
下流GV
Once the safety certiﬁcate is issued (expected on 22 Feb), HER operation will
Duct
D11C
D11D
上流側ダクト下流側ダクトstart on Beam
24 Feb.
Other
systems
MR RF
System are overall stable (some upgrades are ongoing/planned.)•e‐
Tsukuba

超伝
昇

D11D

、か
ップ

20C まとめミーティング RF SYSTEM

TMP[M. Nishiwaki, Y. Morita]

追加ポンプでの排気によりTMP
1/19 空洞交換作業終了
D11D空洞真空
2/1-2/2 シールド復旧作業
2～3e‐7Pa → ～5e‐8Pa– クレーンを占有します
通常の真空ポンプ • 2/4 トリスタン空洞搬出作業
ビーム運転中は、隣の空洞からも空洞：イオンポンプ 2台排気されるため、最大ビーム電流–
場所：日光ビームライン側B4
ダクト：イオンポンプ
1台、
D7
時でも～4e‐8Pa
NEGポンプ 5台– 9：00作業開始
D8– 搬出業者：双葉工業
2021/1/15
2020C まとめミーティング RF SYSTEM
4–
搬出に当たって電磁石架台を少し移動します
FUJI
Oct. 2020
Jan. 2021
3 – 搬出後架台を元の位置に戻します– 当日はクレーンや日光搬入口を占有します

•
•

OHO
D5

ら1日

ダクト部分にTMP+DPを追加
D4

しない

NIKKO
D10 D11間にAngle Valve
超伝導空洞作業報告
(AV)

TMP

14

•

were examined at first.
However, it was finally found that little improvement was
expected even without beam-beam effect.

Optics• On the other tuning
hand, it was also found in the simulation

QCSR configurationthat the effect will be cured using the rotatablesextupole magnets installed in the local correction
N. Ohuchi
Stableinjectionand ring operation at high beam currents
regionat Tsukuba.
Rotatable Sextupole magnet
Chromatic
X-Y
couplings,
octupole,etc.
• We will try
it thisduring 2021
run.

•
•
• Rotatable sextuple controllable remotely canbe used for lumi. tuning (under development).
• Investigation of orbit and beam size ﬂuctuations (1/f ~ 57 s, 200 s…)
M. Masuzawa

Beam size oscillation disappears for single beam.

Oscillation appears with collision depending on ILER.
2020.12.17 6:00 - 8:00 (collision)~57 s[Y. Ohnishi]
152

Summary• One of the big issues found in 2020c was a limit of the bunch current due to••high impedance of the carbon-head collimator at D06V1.
Tantalum-head collimator will be re-used at D06V1 since 2021a.
Continuous eﬀorts to establish stable injection, and two-bunch at 25 Hz
Upgraded bucket selection oﬀers a greater degree of ﬂexibly in injection.
Beam size and orbit oscillations with 1/f ~57 sec. still remain as homework.
Would systematic and comprehensive measurements oﬀer hints?

•••• All hardware and software are maintained by experts and ready for 2021a.

16

BackupWhy we used C-head collimator at D06V1?
• Unstable beams sometimes directly collided with collimators utilized for BG
suppression, e.g. D02V1. Such collisions heavily damaged the collimators.
• D06V1 collimator is expected to guard the collimators for BG suppression
from abnormal beams.
• High-z materials is good for a beam-tail shield though, the beam loss islocalized followed by high temperature exceeding the melting point.
• During the 2020 summer shutdown, the tantalum-head of the D06V1
collimator used in 2020a+b were replaced with a newly-developed
carbon head (low-z).
beam[T. Ishibashi, S. Terui]
5 mmbottom side jaw
beam

60 mm

top side jaw

18

[Y. Ohnishi, 2020c Summary Meeting]History of Phase 3⇤
y = 3 mm⇤y = 2 mm<latexit sha1_base64="6U1Uy6+QDdPwaAB8M1Ixlm/EGD0=">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</latexit>⇤
y = 1 mm<latexit sha1_base64="GVZgwVpyuXOis4y4nrkl2dRxyj4=">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</latexit>⇤
y = 1 mm⇤y = 0.8 mm<latexit sha1_base64="KF1P6OS6NphHraCHHsvQJ4vhjxY=">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</latexit><latexit sha1_base64="fsgdqPw6aDqFJy7GDrU2wHQ88Gw=">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</latexit>

Summershutdown<latexit sha1_base64="fsgdqPw6aDqFJy7GDrU2wHQ88Gw=">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</latexit>

Wintershutdown

Summershutdown

low-z
collimatorfire at Nextef(neighbor of linac)

1.88 x 1034 cm-2s-1

Crab Wast

60 days1.23 x 1034 cm-2s-1

91 days

2.4 x 1034 cm-2s-1
1.48 x 1034 cm-2s-1

57 days
127 days

2019

2019ab

2019c192020 2020ab

2020c

[Y. Ohnishi, 2020c Summary Meeting]

Optics Variations
We tested 6 optics variations during 2020c. VacuumLER
βx* / βy*CW80 / 180 %HERβx* / βy*CW60 / 140 %80 / 180 %80 / 20%C80 / 20%80 / 10%A180 / 180 %80 / 10%A280 / 180 %

60 / 140 %A380 / 180 %

60 / 140 %Optics ID

A0

B

B

A0

scrubbingRemarks
Reference
Same as2020abBTe abnormal
orbit (different
backlegparameter)
LER
steering
HER βx* = 80 >60 mm
LER steering
LER QCS
correctors
HER
same as
LERissteering
LER QCS
correctors
HER
same asLER iscollimatorphase
Based on A0
HER is same as
20

Bad BTe

Vacuum C A1 A2 A0 A3
scrubbing[Y. Ohnishi, 2020c Summary Meeting]Operation in 2020c
QCS quench
Bad BTe params
D02V1 damageB

A0

LER steering

Vacuum C
scrubbing

A1 A2

LER collimator
phase

A0

A3

QCS quench
Bad BTe paramsD02V1 damage

B

The second A0 could not reproduce the first A0 for Lsp.
BG level became almost same as November 13.
* The plots are peak value for 1 hour
21

A0

HER BG GOOD
LER BG GOOD

LER collimatorphase

LER steering

Vacuum C A1
scrubbing

A2

A0

A3

HER BG GOOD
LER VXD BG BAD
LER BG BADTOP is GOOD

* The plots are average for 1 hour.

[Y. Ohnishi, 2020c Summary Meeting]Comparison of Specific Luminositycific luminosity in 2020c was improved from 2020ab.
same optics
as 2020abA0βy* = 1 mm

LER steering
HER is same as A0
A2maintenancemaintenancemaintenance

LER : 485 mA (0.5 mA)
HER : 440mA (0.45 mA
QCS quench nb : 978D02V1 damage<L> : 1.36 x 1034

22

[Y. Ohnishi, 2020c Summary Meeting]High Bunch Current Study: Specific Luminosity
High Bunch Current Study

totalluminosity

nb = 393 bunches
I = 200 - 270 mA
2020.12.08 15:15 - 16:30 (LER = HER)

specificluminosity
Lsp =<latexit sha1_base64="dwIf/5wVA3Bi4qhnRGqDLQeU/9A=">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</latexit>⌃⇤y =<latexit sha1_base64="d4XJNbbd5/wNgiOChvfNcCpLfXA=">AAACmHicSyrIySwuMTC4ycjEzMLKxs7BycXNw8vHLyAoFFacX1qUnBqanJ+TXxSRlFicmpOZlxpaklmSkxpRUJSamJuUkxqelO0Mkg8vSy0qzszPCympLEiNzU1Mz8tMy0xOLAEKxQsYxwRnpucmxlfGadnGFBcWlVTHFIMFqiu1a+OqtYxqteECuhCB2ngBZQM9AzBQwGQYQhnKDFAQkC+wnCGGIYUhnyGZoZQhlyGVIY+hBMjOYUhkKAbCaAZDBgOGAqBYLEM1UKwIyMoEy6cy1DJwAfWWAlWlAlUkAkWzgWQ6kBcNFc0D8kFmFoN1JwNtyQHiIqBOBQZVg6sGKw0+G5wwWG3w0uAPTrOqwWaA3FIJpJMgelML4vm7JIK/E9SVC6RLGDIQuvC6uYQhjcEC7NZMoNsLwCIgXyRD9JdVTf8cbBWkWq1msMjgNdD9Cw1uGhwG+iCv7Evy0sDUoNkMXMAIMEQPbkxGmJGeoYGeYaCJsoMNNCo4GKQZlBg0gOFtzuDA4MEQwBAKtHcmw36GEwwnmaSYHJjcmTwhSpkYoXqEGVAAUxAAeyWeCQ==</latexit>

Lnb Ib+ Ib

q

⇤2
y+ +

200
mA

250 270
mA mA

⇤2
y

Beam-Beamparameter⌃⇤y = 0.32 µm (0.0024 mA2 )BB scan with small bunch current<latexit sha1_base64="AL+xXpJza5yHhGOoEJvPCZV61s8=">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</latexit>⇤
2ere y±
L
⇠y± =
± I±
<latexit sha1_base64="R/f84uPHPF8Q3b1QYuK+4UI7i9s=">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</latexit>

Lsp = 6 x 1031 at 0.3 mA2 (Ib = 0.55 mA, nb=393)
23

[Y. Ohnishi, 2020c Summary Meeting]Single Bunch Tune Shift in LER
Tune shift is same assynchrotron tune⌫s =<latexit sha1_base64="d0MeoqsnyYssj6rLpfn7z/vQe5I=">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</latexit>

0.0235

H: -0.0019Dec. 17
V: -0.0229

single bunch
current

vert. tune

eam current can not be stored larger than 0.8 mA/bunch.
Dec. 17 (A3)

Nov. 5 (A0)

D02V1 (mm)1.68 / 1.2 (1.44)

1.52 / 1.2 (1.36)

D03V1 (mm)2.0 / 1.98 (1.99)

D06V1 (mm)0.68 / 1.38
(1.03)
2.7 / 1.2 (1.95)

D06V2 (mm)2.28 / 1.85 (2.07)

2.2 / 1.9 (2.05)

carbon head

H: -0.0018Nov. 5
V: -0.0131

3.2 / 3.2 (3.2)

24[Y. Ohnishi, 2020c Summary Meeting]Operation Statistics
Physics Run
Machine Tuning
Machine Study
TroublesMaintenance, others① From
We want
to increase
machineavailability
for physics
run asaftermuc②
2021a,
we moveon physics
run as soon
as possible④ Maintenance is usually
maintenanceeven
the develop
possibleabeta*
is 2 mm
in17:00,
the day.
until③ wethough
gradually
resumption
strategy
and try to reduce minjection tuning for PF and
PF-ARthen SuperKEKB injection
tuningstarts. Startup with stable
operation of linac injector
Physics run: 33 %Physics run: 59 %Physics run: 37 %is a key point to resume
Machine tuning: 47 % Machine tuning: 28 % Machine tuning: 47 %SuperKEKB⑤ Linac injector tuning should be
as quick as possible.
2019c was dedicated tosimilar statistics as needed. (Wednesday is advant
the machine tuning.
coincidentally ? a disturbance for PF and PF-AR is
2019c

17%

2020a/b

5%

2%

4%

7%

12%

1%

33%

1%

2020c

37%

28%

59%

47%

47%

25

[Y. Ohnishi, 2020c Summary Meeting]Troubles
Group
LINAC
MG
RF
VAC
Infrastructure
DR

BTp
BTe

Devicesafetycharge limit
QCS
QEAP_44
D11AB KPS
air fin cooler (AFC)D11A HOM chiller
D02V1
water cooling pump (NIKKO)DR ext. septum
BL1S_1_2
DR Inj. kicker
DR inj. kicker
QRF
BV2P_1_2
BH1BP
B2P_2
QAD9P
BV2E_4

Content
Linac Ready
1S abort
QC1RP quench
PS tracking error
crowbar work, solenoid PS
frozen (human error)
compressor abnormal
damage, replace headmalfunction → vacuum leakage at LER
cooling water abnormal
magnet water stop
PS fault
reserver PS communication error
magnet water low rate
magnet water stopabnormal water flow rate
magnet water stop
PS Tracking I/L
PS OV

hour:mi
0:17
0:57
1:17
0:59
14:09
3:16
2:51
174:26
1:28
1:43
0:32
2:19
0:37
0:47
2:18
0:46
1:58
1:19
1:16

#
1
1
1
1
1
1
2
1
1
2
1
1
1
1
1
1
3
1

DR inj./ext. kicker communication fault: no. incident is 51 (< 15 min fore26

[Y. Ohnishi, 2020c Summary Meeting]Operation Statistics
Machinestudy
0.0

Troubles

0.0

Machinetuning102.0

total (hours)

0.0

Maintenanceand others
10.0

March

344.0

314.5

0.0

17.5

68.0

744.0

April

468.0

135.0

0.0

71.5

45.5

720.0

May

525.0

133.5

0.0

26.0

59.5

744.0

June

463.0

153.5

28.0

50.5

25.0

720.0

July

9.0

0.0

0.0

0.0

0.0

9.0

total (hours)

838.5
27.5 %
536.6

28.0
0.9 %
0.0

165.5
5.4 %
8.3

208.0
6.8 %
45.1

3049.0

October

1809.059.3 %
37.2

November

324.7

180.6

0.0

197.2

17.7

630.2

December

283.8

111.0

0.0

6.5

15.8

417.1

total (hours)

645.7
36.6 %

828.2
46.9 %

0.0
0.0 %

212.0
12.0 %

78.6
4.5 %1764.52020

Physics run

February

112.0

627.2

27

[Y. Ohnishi, 2020c Summary Meeting]Comparison between 2020b(June) and 2020c(November)
2020b
HER injection was good.

2020c (~Nov.12)
HER injection was terrible.
e-: 1.3 nC/bunch 12.5 Hz

30

VXD BG was verysmall.

28