Phase-3 Commissioning Road Map
Akio Morita
SuperKEKB Commissioning Group

B2GM 2018.10.15

Luminosity Target for Early Phase-3●Until 2019.06– (1)1.06 x 1034 cm-2s-1 (conservative ξy ~ 0.026)y ~ 0.026)

Note: ξy ~ 0.026)y ~ 0.021 is achieved in phase-2.

βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* ~ 3mm collision with I ~ 1.2 x 1.0A●
Increase beam current from phase-2 collision operation.
●– (1ex) 1.46 x 1034 cm-2s-1 (aggressive ξy ~ 0.026)y ~ 0.033)●●

βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* ~ 3mm / σ*y ~ 670 x 830nm / I ~ 1.4 x 1.0A

Around 2019.12 ~ 2020.02– (2)2.08 x 1034 cm-2s-1 (conservative ξy ~ 0.026)y ~ 0.028)

βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* ~ 2mm / σ*y ~ 525nm / I ~ 1.4 x 1.0A●
Single beam & low current operation of βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* = 2mm optics is confirmed in phase-2.
●– (2ex) 3.14 x 1034 cm-2s-1 (aggressive ξy ~ 0.026)y ~ 0.035)●●

βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* ~ 2mm / σ*y ~ 510nm / I ~ 1.7 x 1.2AUntil 2020.06– (3)●4.00 x 1034 cm-2s-1 (conservative ξy ~ 0.026)y ~ 0.030)

βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* ~ 1.4mm / σ*y ~ 440nm / I ~ 1.8 x 1.3A– (3ex) 6.20 x 1034 cm-2s-1 (aggressive ξy ~ 0.026)y ~ 0.037)●

βy* ~ 3mm collision with I ~ 1.2 x 1.0Ay* ~ 1.2mm / σ*y ~ 350nm / I ~ 2.0 x 1.4A

Luminosity Projection
Lint Assumptions●●

46fb-1

Bad BG case

Winter Shutdown●

Lpeak increases linearly during beam operation.
Efficiency Lavg / Lpeak ~ 70%
Belle works 24H during beam operation.(98days for 2019 spring run)
Belle CAN take data with high beam current operation.(No BG limit)

Summer Shutdown●

49fb-1

No improvements from Phase-2.
Beam current is limited by BG.
●
Sample from 2019.07.01 morning●
Lpeak limit~ 0.2 x 1034 cm-2s-1●
I ~ 290 x 270 mA→ Lint in 2019 Spring ~ 11.8 fb-1●
●289fb-1

Timeline: 2019.03 ~ 2019.06
MarchWeek #10 11AprilMayJune

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Reestablish phase-2 collisionβy* ~ 3mm collision with I ~ 1.2 x 1.0A*y = 3mmTop-up Inj. BG study
Adiabatic tuning with Belle ON* Luminosity tuning* Beam current increasing

Good BG case

Extended BG study mode
09~21: BG & machine study
21~09: Physics run

Bad BG case

Energy Scan
-60MeV Data Taking
24H Physics Run
High current challenge

Summer ShutdownStart-up

Rough plan after 2019.10●

2019.10– Start-up + Reestablish collision: 2~3weeks●

2019.11– Adiabatic tuning– βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y = 2 mm collision trial?

●2019.12 ~ 2020.01– Adiabatic tuning– Winter Shutdown: 2.5~3weeks– Restart collision: 1.5~2weeks●

2020.02 ~ 2020.06– Adiabatic tuning– Adiabatic βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y squeezing trial down to 1.x mm & collision trial●

2020.07 ~ 2020.12 or 2012.01– Extended summer shutdown for Belle II detector works.

Issues from Phase-2 Operation●QCS Quench– New H & V beam collimators are installed. It would be useful to protect QCS.
– Additional W shield for QCS is considering for protecting QCS and reducing beam background.

●High Current Beam Operation– Longitudinal coupled bunch instability is observed in LER I > 850mA.
●

Preparing longitudinal feedback system.

– Need hardware commissioning & tuning to increase beam current beyond 1 A. (RF system/vacuumcomponents/monitor/feedback)●●Maximum operated beam current: LER 1010mA / 858mA (Phase-1/Phase-2) HER 870mA / 788mA (Phase-1/Phase-2)

Beam-Beam Parameter Limit– Achieved ξy ~ 0.026)y in phase-2 is about 0.021.
– IP linear coupling is adjusted in phase-2.
– This limitation would be caused by IP non-linear coupling, however, source term is not identified.

Simulation study and examination of measurement method are started.
●
Consider to activate LER sextupole rotator to adjust chromatic IP coupling.
●– New skew sextupole for HER is under consideration. (KEKB’s skew sextupoles are already removed & reused by ATF.)●Consider to activate non-linear QCS correctors.

Tentative Target Parameter(1)
LER

HER

εx[nm]

2.0

4.6εy/εx[%]

8.0

8.0

βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]33σz[mm]

66I[A]

1.2

1.0nb

1576

Bunch Current[mA]

0.761.635

σ*y[nm]6931051

ξy ~ 0.026)y0.0262

0.0272L[cm-2 s-1]

1.06 x 1034

Tentative Target Parameter(1ex)
LERHERεx[nm]

2.0

4.6εy/εx[%]7.55.0βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]33σz[mm]

66I[A]

1.41.0nb1576

Bunch Current[mA]

0.888

.635

σ*y[nm]

670830ξy ~ 0.026)y

0.03310.0328L[cm-2 s-1]

1.46 x 1034

Tentative Target Parameter(2)
LER

HER

εx[nm]

2.0

4.6

εy/εx[%]

7.0

3.0

βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]22σz[mm]

66I[A]

1.4

1.0nb1576

Bunch Current[mA]

0.888.635

σ*y[nm]529525ξy ~ 0.026)y

0.03510.0278L[cm-2 s-1]

2.08 x 1034

Tentative Target Parameter(2ex)
LER

HER

εx[nm]

2.0

4.6

εy/εx[%]

6.5

2.8

βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]22

σz[mm]

66I[A]

1.7

1.2nb

1576

Bunch Current[mA]

1.079.761

σ*y[nm]510508ξy ~ 0.026)y

0.04360.0351L[cm-2 s-1]

3.14 x 1034

Tentative Target Parameter(3)
LER

HER

εx[nm]

2.0

4.6εy/εx[%]

7.0

3.0

βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]

1.4

1.4

σz[mm]

66I[A]

1.8

1.3nb1576

Bunch Current[mA]

1.142.824

σ*y[nm]442

439

ξy ~ 0.026)y

0.03870.0302L[cm-2 s-1]

4.11 x 1034

Tentative Target Parameter(3’)
LERHERεx[nm]

2.0

4.6εy/εx[%]5.02.2βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]1.251.25σz[mm]

66I[A]

1.6

1.15

nb1576

Bunch Current[mA]

1.015.730

σ*y[nm]354356ξy ~ 0.026)y

0.03970.0301

L[cm-2 s-1]

4.00 x 1034

Tentative Target Parameter(3ex)
LER

HER

εx[nm]

2.0

4.6

εy/εx[%]

5.0

2.2

βy* ~ 3mm collision with I ~ 1.2 x 1.0A*x[mm]100100βy* ~ 3mm collision with I ~ 1.2 x 1.0A*y[mm]

1.2

1.2

σz[mm]

66I[A]

2.0

1.4nb

1576

Bunch Current[mA]

1.142.824

σ*y[nm]346

348

ξy ~ 0.026)y

0.04530.0369L[cm-2 s-1]

6.20 x 1034