KEKB Status
since Feb. 2004
H. KoisoFeb. 21, 2005 @ KEKB Review•••

Achieved 15/nb/s
Achieved 1/fb/dayPlansKEKB History
Continuous Injection™

Last Review

KEKB Performance Feb. 2004 - Feb. 2005
HERBellows@LER IRLER

PS noise

Luminosity

15.16/nb/s

Spec. Lum.

Luminosity Performance• Both peak and integrated luminosities havebeen improved.
Lpeak= 11.61 → 15.16/nb/s∫L/day, /7days, /30days= 819/4745/17240 → 1083/6242/23995 /pb• Total luminosity 197.5 → 363.4/fb• Now we guarantee 19.5 → 25.8/fb/month toBelle.

The Best Day 1082.8/pb

Daily Luminosity since Jan. 2004

Machine parametersDate

2/15/2005

RingLER

Horizontal Emittance

HER

18

Beam current

12/18/2003
241636

Number of bunches

LER
18

1261

1.27

0.975

1.8 or 2.4 (3.77sp)

Bunch trains

1103

116

Vertical size at IP

2.1

2.1

0.884

1.8 or 2.4 (3.77sp)
103

116
µm

5.5

3.4%

59/0.58

56/0.7cm

0.074/0.056

0.104/0.069

0.071/0.053

160 @1503 mA 195@1132 mA

125@1503mA

216@1132mA

11.61/nb/s59/0.54

Beam-beam parametersξx/ξy0.118/0.081

mAmAm

2.3

β*x/β*yLuminosity records
per day/7 days/30 days

1.17

2.3

Emittance ratio εy/εx

Luminosity (Belle CsI)

1132

1Horizontal size at IP σ*x

Beam lifetime at collision

nm

1281

Bunch spacing

σ*y241503

1293

Bunch current

HER

56/0.62

15.16(total)
1083/6242/23995 (363.4/fb)

819/4745/17240 (197.5/fb)

min/pbµm

Machine Parameters (cont’d)• Bunch fill pattern/bunch spacing– 3.77 (49/13) + “Breakwater”– 3.5 (49/14) Specific luminosity wasdegraded by 5~10%.
– 3.06 (49/16) in Dec. 2004

• Stored currents– LER ~1500 → 1674 mA– HER 1187 → 1270 mA world’s highestwith SCC• RF Voltage– LER 8 MV
– HER 13MV(7 SCCs, before July 2004), 15 MV(8 SCCs)Luminosity（3.77 v.s. 3.5）
Y. Funakoshi

3.5

3.77
Needs More Study!

Continuous Injection Mode

2004 Feb.

2005 Feb.

• 3.5 msec veto at injection.
• 10 Hz injection. → 25 and 50 Hz are also available.
• e+/e- mode change in every 20 min. → 5-10 min.
• Heating of the septum chamber limited LER current. → No clear
limit for LER current in < 1800 mA.

“Breakwater bunches”“Breakwater bunches” enables the lower vertical tune.

Tune Feedback
Diff. is kept
<0.0003

measuredcorrected
bunch-current
dependenceWorks very wellT. Ieiri and Y. Ohnishi, et al.

Working Point Survey

Progress in the Specific Luminosity
June 2004 (CIM)(4)

Feb 2005 (CIM)
Oct. 2002

Dec. 2003 (pre-CIM)

Both the specific luminosity and the average
operating currents are improving.

Detection & compensation of BPM motion
relative to sextupole magnet•Heating of beam pipe
pushes BPMs and magnets,
causing displacement ofBPMs relative to sextupoles.

Hor. & Ver. Electrostatic
displacement monitor•Electrostatic gauge was
attached to sextupoles in
LER local chromaticity
correction section tomeasure the BPM
displacement.
•Correction is added to BPM
reading to stabilize orbit
relative to sextupole center.
•Very good result.
BPM
Sextupole
Quadrupole
M. Tejima, M. Arinaga, et al•Necessary for all
sextupoles in future.
•Must be compatible withsextupole movers.

BPM gauge was effective to suppress the tune drift.
Disp. (mm)v. Tune set

v. Tune measured

Before compensation

After compensation

Drift of βy*
due toBPM motion

Estimated βy*(m)PS onsetPermanent magnets (“C-Yoke”) in LER

C-Yoke•1,600 sets of C-Yokes were installed in LER at gaps of solenoids.
•Effects are not yet noticed.
M. Suetake and H. Fukuma

Noise from KEK Proton Synchrotron(PS)PS 12 GeV, 2.2 sec (for K2K)

•Power supplies for
KEKB quadrupoles wereaffected by PS, probably
through magnetic fluxchange.
•Tunes of KEKB rings
were modulated.
•Improved by making
the power supplies’
response faster, but…

Δνy ~0.0033 (p-p)

Self oscillation of KEKB
quad power supply•Later PS went shut
down by failure in theelectro-magnetic horn.

Tune modulation by PS•Horizontal tune of LER was modulated by PS (left).
The luminosity degraded by more than 10%.
•After fastening the response of quad power
supplies, the modulation was reduced (right).
•The luminosity was recovered by this fix.
M. Yoshida et alTrouble of LER IR Bellows
QC1RE QC2RP
H24QC2RE

H23IP

QC1RE

H23A

Bellows
One of the bellows in LER near IP
was damaged around Nov. 3.

K. Kanazawa,Y. Suetsugu et al

IR Bellows•Both temperature (left) and pressure (right) rose at high current.
•Since then, LER current has been limited to below 900 mA (was1650 mA before).
•Operating at very bad current ratio degrades the specificluminosity.
•The bellows were fixed during the winter shutdown.

Similar Troubles at IP Bellows• HER QC1LE bellows in March 2004.
• LER QC1RE bellows in Nov. 2004.
• They were replaced to new bellows with more welding
points to fix fingers.

The RF contact was separated from the chamber.

K. Kanazawa,Y. Suetsugu et alReplacement of Vacuum Chamber
in HER IR•Replaced on both R&L sides•cavity structure → straight•HOM absorbers were damaged.
HOM absorbers

drift space reserved for a crab cavity
Y. Suetsugu et alDamaged HOM Absorber -Ferrite

Y. Suetsugu, et al.

Damaged HOM Absorber - SiC

Y. Suetsugu, et al.

Troubles on Transverse Feedback Kicker

Two Cu electrodes on the down side were damaged.
They were replaced to new SUS electrodes with Cu coating.
Feed through connectors were also replaced.

Recent Performance

FB tuning
New sextupole
correction

maintenance

7 days record

LER FB

maintenance

QCS quenchearthquake

Strange Abort Rush in LER
beam phasecurrent•Belle abort by SVD PIN signals•Beam loss
•Phase oscillation - caused by energy loss?
•No transverse oscillation•No pressure burst
Dust?
Disappeared after the earthquake
on Feb. 16?

Injector Performance• 2 bunch/pulse e+ injection scheme are always applied.
• The injection rate from Linac to the rings are stable.
Y. Ogawa, et al.

Beam Aborts

H. Ikeda, et al.

OperationStatistics

T. Kawasumi, et al.

PlansHigher Currents• HER current is gradually being increased.
1270 → 1300 mA → · · ·• LER current
1674→ ~1800mA
Limit depends on luminosity performance.

Higher Specific Luminosity• Optimize βx/y* in both rings• Better choice of tunes and chromaticity corrections– Larger dynamic aperture– Weaken the effect of the synchro-betatron resonanceνx + νs = integer ( νx = .511 at Vc = 13 MV)

2

Synchrotron-betatron resonance in HER

Lifetime (min)νs = -0.0217

2νx + νs = int.

K. Oide, et al.

HER νxTune shift byresistive wall
0A→1A

Plans (cont’d)More Bunches• 3.5 spacing

We will install crab cavities in both rings in Jan.
2006.
• One cavity in Nikko straight section in each ring
• Achieve ξy >.1 with crab cavities

Luminosity before Crab Cavities• Total integrated luminosity >500/fb• 25.8/fb/month– = 0.86/fb/day × 30 days

• >200/fb/year