KEKB Status (before crab)
since March 2006
Y. Funakoshi
March 19, 2007 @ KEKB Review

KEKB PerformanceKEKB History

Last Review

KEKB Performance Apr. 2006 - Dec. 2006
HER
Deceasecurrent

Deceasecurrent

5S

LER
Skew
problemfound

Luminosity
Fast
Luminosity
Recovery

Spec.
Lum.

LER
lower εx

SX
TuningLER

Luminosity Performance• Both peak and integrated luminosities havebeen improved.
Lpeak= 16.27 → 17.12/nb/s∫L/day, /7days, /30days= 1183/7358/29018 → 1232/7809/30208 /pb• Annual integrated luminosity
188.7(2005: 274days) /fb/year→ 180.8(2006: 227days) /fb/year• Total luminosity 563.3 → 710.3/fb

The Best Day 1242.7/pb

History of Daily Luminosity
Last Review

History of Weekly Luminosity
Last Review

Machine parameters
Date

Nov/15/2006

Ring

LER

Horizontal Emittance

HER

18

Beam current

24

1662

Number of bunches

Dec/19/2005
LER
181340

1.20

0.965

1.8 or 2.4 (3.5sp)

Bunch trains

1103116

Vertical size at IP

1.9

1.9

β*x/β*y1347

mA

1.23

0.970

mA

1.8 or 2.4 (3.5sp)

m1

Horizontal size at IP σ*xBetatron tune νx/νy

nm

1388

Bunch spacing

σ*y241719

1388

Bunch current

HER

45.505/43.534

44.509/41.565

59/0.65

103
2.1

116
2.1µm

45.506/43.531

44.512/41.578

56/0.59

59/0.65

56/0.620.070/0.056

0.117/0.096

0.073/0.055cm

Beam-beam parametersξx/ξyBeam lifetime at collision
Luminosity (Belle CsI)
Luminosity records
per day/7 days/30 days

0.117/0.105

110 @1600 mA 180@1340mA
17.12

135@1719mA

222@1347mA

16.27

min/nb/s(total)1232/7809/30208 (710/fb)

1183/7358/29018 (560/fb)/pbµmMachine Parameters (cont’d)• Bunch fill pattern/bunch spacing– 3.5 (49/14) : physics run same aslast KEKB review– 3.27 (49/15) Test run in Dec. 2006

• Stored currents– LER ~<1700 mA– HER 1350 → 1400 mA → 1350 mAworld’s highest with SCC• RF Voltage– LER 8 MV
– HER 15 MV

Υ(5S) Run
Υ(4S)

Scan
Lower Limit

Υ(5S)

Scan
Upper Limit

Note

Center of massenergy [GeV]

10.5800±0.0035

10.82510.865±0.008

10.905

Physics

EnergyRatio

11.0232

1.02691.0307Instability
Beam-Beam

HER [GeV]

8.0

8.185

8.216

8.246

Linac margin?
BT?
Ring steering?

LER [GeV]

3.5

3.581

3.594

3.608

BT?
Ring steering?

(E/E0)^4

1

1.09591.1122

1.1287

Radiation
Loss(E/E0)^3

1

1.07111.08301.0950Damping Rate

(E/E0)^(-2)

1

0.9552

0.94830.9413

BhabhaCross Section

HER current was decreased by 11% to keep the radiation power same as at Y(4S).
Shorter damping time may have boosted the luminosity.

Luminosity Records (as of Jun. 30 2006)
2005

2006 4Speaknb-1s-1

16.270

shift

pb-1

401.8

day

pb-1

1182.524 hrspb-1

1206.6

week

fb-1

7.096

7 days

fb-1

7.358

month

fb-1

27.88730 daysfb-1

29.01816.51705.12.19 5:01

06.6.30 2:31

402.6

05.12.6E

05.12.6

05.12.7 7:15

2006 5S

06.5.31M

1201.706.5.31426.4
06.6.28M

1231.506.6.26

1243.706.6.27 10:42

7.206

05.3.14-3.20

06.6.19-6.25

7.819

05.3.17-3.23

05.5

05.3.10-4.9

06.6.22-6.28

29.38806.6

30.20806.6.22-6.28

Operational difficultyTroubles of standard bellows in HER• Frequent breaks of HER arcbellows– three times before summer– downstream of bending magnets(high power of SR)• Deformation of bellows– Large offsets of bellows (relative
movement of upstream anddownstream flanges) were observedin hor. direction. (Δx: 1.5 ~2.5 mm)– Those offset may bring the breaks.

D03 broken bellows• Countermeasures (during summer)– Supports which prevent the offsets(80 bellows) -> (Δx: <1 mm)– Two spare bellows with a revised
designY. Suetsugu

Measurements with dial-gauge• Relative movement of up and downstream flanges(max. value)+1.74 D3
From upstream

QD1E.21

QF2E.41

B2E.96+2.36-1.09+~1.9-~0.6+2.9+2.7

D5

QF6E.21B2E.94

QD3E.35

QD5E.41-0.76

2006.06.19 - 06.21+4.14+:Outside、-:Inside

x1QF4E.35 QEAE.42

QD5E.42

B2E.95 QF6E.21

D8 (@1350mA)

x2+1QEAE.41

QF4E.34 QD3E.34

Broken Bellows：Large movement

B2E.93

QF2E.40 QD1E.20
Y. Suetsugu

outside

Realtime measurements with displacement meters

[B]

[Q]
abort

insideinjection

H: upstream
V: downstream
Y. Suetsugu

Reproducibility of luminosity• Integrated luminosity– Recovery of luminosity after long-shutdown– Recovery of luminosity after short operation break(such as regular maintenance)• It deprives us of opportunities of other trials for a higherluminosity.
• In May last year, we found out one of sources which bring badluminosity recovery.

Strong correlation between the achieved peak luminosity
and the polarity of one of skew-Q magnet(QKCLP) in LER

2A<-> K valueof 1.5 x10-4 /m

This skew-Q magnet is very weak. In the process of the optics correction, thepolarity was easily changed, although the precision of the optics measurement
is not enough to distinguish their difference. Since the magnet current between-2A and +2A could not be set due to a software problem, the actual magnet
current was set either at around -2A or around + 2A.

KEKB Performance Feb. 2005 - Mar. 2006
HER

It took about 2.5 month to recover
performance before shutdown !!
LERHighCurrent
Trial

Bellows
TroubleLuminosity

Belle
Solenoid

Craboptics

Spec.
Lum.

Belle
SVD

16.27/nb/s

KEKB Performance Apr. 2006 - Dec. 2006
HERDecease
current

Deceasecurrent

5S

LER
Skew
problemfound

Luminosity
Fast
Luminosity
Recovery

Spec.
Lum.

LER
lower εx

SX
TuningLER

Safety system trouble

LER Optics change
IP<-> FB monitor phase

LER lower emittance
Regular maintenance

LER Optics change
SRM βyLER SX Tuning• Methods of tuning– Strength of each pair of sextupole magnets– Scan R and Twiss parameters by changing strength of allsextuple magnets• Effectiveness of this tuning– almost 30% difference in luminosity• Mystery– What is the difference from the usual IP knob tuning?

• Key issue related to the luminosity reproducibility
problem?
– BPM displacement sensors may be important.

Scan of one of SX pair
Scan of strength of SD3TRP
with all constraints for R andTwiss parameters

without constraint forR4
R4 4.3units

Scan of usual IP knob

Luminosity is sensitive to the strength of sextupole magnets.
The effect can not be reproduced by the usual IP knob.

New Sextupole Tuning panel

Emergency Stop(Safety system)M

M

LER lower emittance

MLower HER νxM
βx* -> 50cm

MM

3.5 −> 3.27 spacing
LER SX tuning
Off-resonanceSearch for better machineparametersPredicted luminosity by beam-beam simulations
Horizontal emittance

HER Tune(νx, νy) = (.511, .568) -> (.509, .563)
L=1.381e31 -> 1.451e31 (5% up)

This trial

original

βx*
βX=56(HER) βX=59(LER) L=1.381e31
βX=50(HER) βX=50(LER) L=1.466e31 <- 6% up
βX=40(HER) βX=40(LER) L=1.326e31
βX=30(HER) βX=30(LER) L=1.217e31

~5% upin luminosity

We succeeded to lower the HER horizontal tune
by tuning HER sextupole magnets.

lower the HERhorizontal tune

Trial of LER lower emittance optics• LER emittance– 18nm -> 10nm

• Motivation– 7.7% increase of luminosity was predicted by the beam-beam simulation.

• Unexpected difficulty– We retreated from the trial due to frequent beam aborts accompanied byhorizontal oscillations of both beams.
– Beam-beam simulations showed that coherent synchro-beta oscillationsdue to the beam-beam effect tend to be excited with smaller emittances
and tunes close to the half integer (Ohmi). More simulations are underway.

• Achieved luminosity– Lpeak = 13.972 /nb/s (cf. 15.845 /nb/s with ex=18nm)– After returning to the original optics, the recovery of the luminosity wasvery slow.
– It is not easy to make a critical comparison of 18 and 10nm optics withthe short-term trial.

LER low emittance Emit x =10 nm
A. Morita

32.0 nm 4.53E-4

17.8 nm 3.31E-4

εxα

13.7 nm 5.30E-49.9 nm 3.37E-4εxαtune(45.504, 43.540)

Safety system trouble

LER Optics change
IP<-> FB monitor phase

LER lower emittance
Regular maintenance

LER Optics change
SRM βyOther trial• New power supplies of solenoid coils– In summer 2006, we replaced 50 power supplies of solenoids
in straight sections.
– With the power supplies, the currents of 1452 solenoids were increased
from 3A to 5A.
– However, the effectiveness of the new power supplies was not observed.

• Smaller βx*– (βx*(LER), βx*(HER))= (59cm, 56cm) -> (50cm, 50cm)– We could not go to the operating points which give a goodluminosity due to bad beam lifetime.
– It was not easy to test performance with limited tuning time dueto the luminosity reporducibility problem.

Machine Operation Statistics

Abort statistics (total)

H. Ikeda and M. Tanaka

Abort statistics (beam loss aborts)• Causes of beam loss aborts––

failure of tune control
coupled bunch instability•–

Fast ion, electron clouds, beam-beam, RF cavities

vacuum troubles such as bellows breaks

OperationStatistics

FY 2005FY 2006 (Apr. 2006 ~ Dec. 2006)
T. Kawasumi

OperationStatistics(Troubles)

VacMag
RFBelleVacFY 2005
BelleMagRFFY 2006 (Apr. 2006 ~ Dec. 2006)
T. Kawasumi

Trouble Statistics (except Belle)
VacBM

RFcryo.

Vaccontrol

MagMagRF

FY 2006 (~Dec.2006)

FY 2005

Total operation Time [h]4247.54527.5

Trouble Total except Belle [h]

128.5

258.5

Trouble Rate [%]

3.0

5.7

Future plans• To see results of the crab crossing
experimentspare slides

ΔK1=+3E-4