Run plan update&beam background study preparation
Akio Morita
SuperKEKB Commissioning Group

B2GM 2019.02.04

Run plan update(1)Platinum week

No major update from 31st B2GM

Run plan update(2)●Beam operation in platinum week(04.27 ~ 05.06)– CONTINUE beam operation for physics run.
– DOES NOT perform risky study & tuning during platinum week

due to lack of human resource for responding emergency.

– Off-resonance operation during platinum week WOULD NOT

BE realistic.

REMEMBER that we DOES NOT HAVE knowledge of energy scan
operation after machine upgrade.
●We HAVE TO discuss off-resonance & energy scan operation
schedule for preparation.
●

Run plan update(3)●Remarks– HAVE TO confirm function of reassembled & new installed devices.
– HAVE TO perform vacuum scrabbling(20~100Ah).
– Beam background situation MAY be changed due to reassemblage of final focus

system.
●QCS cryostat alignment error is reported(a few hundred micrometers / preliminary).

– QC1* BPM cables are damaged after QCS insertion works.

Fast collision feedback WOULD be limited, however, it was not used in Phase-2 operation.
●Slow orbit measurement is possible, but measurement accuracy WOULD be degreaded.
●– Start up operation schedule in March(~3weeks) DOES NOT contain buffer fortrouble shooting.
●MAY BE delayed due to troubles if occurred.

Run plan update(4)Baseline(conservative) machine parameter target until next summer
Conservative#1 (~2019.06)

RingLER

HER

εx[nm]

2.0

4.6

εy/εx[%]

8.0

8.0

β*y[mm]33

σz[mm]

66

I[A]

1.2

1.0

Number of Bunches

1576

Bunch Current[mA]

0.761

0.635

σ*y[nm]6931051

ξy0.0262

0.0272L[cm-2 s-1]

1.06 x 1034

β*y = 3mm collision is confirmed in Phase-2.
●Maximum stored beam currents are...
0.858 / 0.788 A (LER/HER) in Phase-2
1.010 / 0.879 A in Phase-1 w/o IP●
1576 bunch operation is confirmed in Phase-2.
● Minimum colliding σ* is 333 nm(ultra low bunch current).
y● Maximum ξachieved in Phase-2 is 0.021.
y● Maximum L
achieved in Phase-2 is 0.555 x 1034 cm-2s-1.
peak●Run plan update(5)Integral luminosity estimation until next summer

P-2 recordlbasee nacsin eri oSummer Shutdown

Assumptions of estimation:●Lpeak increases linearly during beam operation from Phase-2 record up-to baseline target performance.
●Efficiency <Llog> / 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)

Baseline scenario: 46fb-1 w/o study→ 23fb-1 assuming 50% study

Worst case scenario(bad BG case)

No BG improvements from Phase-2.
●Log-able Lpeak is limited by BG.
●Lpeak limit~ 0.2 x 1034 cm-2s-1 (Ex. 2018.07.01 morning)→ Lint in 2019 Spring ~ 11.8 fb-1 w/o study→ 5.9 fb-1 assuming 50% study●We HAVE TO improve BG Lpeak limit ASAP
in order to achieve 10fb-1 with study margin.

Beam background study preparation(1)●Study plan was proposed in MDI meeting.
– Detail plan WOULD be discussed on MDI meeting.

●Beam collimator updates from Phase-2 to Phase-3:– Relocate D06H4 to D06H1.
●

LER phase-2 collimator configuration CAN NOT BE reproducible due to absent D06H4.

– Replace damaged collimator head of D02V2 & D01V1.
– Improve D01H4 collimator head cooling(Add booster pump for cooling water).
– Install new collimators.

HER: D01H3(on going)●
LER: D02H1, D02H2, D03H1 and D06V4(this February)●Beam background study preparation(2)●Preparation of tuning knob(1)– Emittance control knob(ECK)ECK based on global dispersion(iSize)●
ECK based on arc localized dispersion(YaECK)●– IP & source point dispersion IS NOT CHANGED in 1 st order perturbationlevel(NOT confirmed by measurement).
– Tuning range is SMALLER than “iSize” due to dispersion free constraints.
– New skew quadrupole corrector(QKSF) WOULD extend tuning range,
however, factor 2 improvement WOULD BE difficult due to matchingconstraints.

Beam background study preparation(3)●Preparation of tuning knob(2)– Tilt knob at source point

REQUIRED in MDI meeting.
●CAN prepare, however, development IS NOT STARTED at this moment.
●– It CAN NOT BE guaranteed whether tuning range is sufficient.
●LER source tilt knob MIGHT change coupling/dispersion at injection point.
– LER injection tuning/background WOULD be interfered.

HER source tilt knob MIGHT change coupling/dispersion at OHO straightsection(wiggler & ARES cavity).
●
Source tilt knob MIGHT interfere with tuning range of “YaECK” due to parameterconflict.
●BackupRough plan after 2019.10●

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

2019.11– Adiabatic tuning– β*y = 2 mm collision trial?

●2019.12 ~ 2020.01– Adiabatic tuning– Winter Shutdown: 2.5~3weeks (+ extra operation interrupt due to power receiving line maintenance?)– Restart collision: 1.5~2weeks●

2020.02 ~ 2020.06– Adiabatic tuning– Adiabatic β*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.