KEKB Status

KEKB Status
12/14/2004 @ PEP-II MAC
K. Oide (KEK)
Topics
• Performance since April, 2004
• Observation of -tron sidebands due to head-tail
motion caused by e-cloud
• Better tunes in LER
• Compensation of BPM motion due to heating
• New permanent magnet (“C-Yoke”) for e-cloud
• Noise by the KEK Proton Synchrotron
• Damage of IR bellows in LER
• Development of crab cavity
• Development of C-band linac
KEKB Performance Apr. - Dec. 2004
HER
Bellows
@LER
IR
LER
PS noise
Luminosity
13.9 /nb/s
Spec. Lum.
Daily Luminosity in 2004
Even worse
and worse?!
944 /pb
May 23
Delivered 1000 /pb/day, 8 times.
The best day
5/23/2004
>1000 /pb/day delivered
944 /pb/day recorded
Machine Parameters (June 3, 2004)
Integrated = 335 /fb (Dec 13, 2004)
Observation of vertical sideband due to e-cloud in LER
V. Tune
Sideband Peak
Synchrotron Tune
100
Bunch
1
0.5
Tune
• LER Single beam, 4/100/4
• Solenoids off
• Vertical Feedback Gain Low (-15.40 dB).
1.0
J. Flanagan, et al
Spectra of Bunches 1-10
Bunch 1
Bunch 6
Bunch 2
Bunch 7
Bunch 3
Bunch 8
Bunch 4
Bunch 9
Bunch 5
Bunch 10
LER Blow-up Study
• Vertical Tune and
Sideband Peaks
increase along
train.
Sideband
Peak
Bunch 5
Betatron
Tune (V)
• Difference
between tune and
peak also
increases, then
saturates near the
40th bunch.
Better tunes in LER
•
•
•
w/parasitic
w/o parasitic
The best vertical tune shifts closer
to 1/2, if parasitic collision is taken
into account (M. Tawada).
KEKB’s luminosity was actually
improved by 5% by lowering the
vertical tune, from 0.543 to 0.535
as the simulation predicts.
Effect of parasitic collision has not
been detected directly yet.
“Breakwater bunches” enables the lower vertical tune.
Detection & compensation of BPM motion relative
to sextupole magnet
•Heating of beam pipe pushes
BPMs and magnets, causing
displacement of BPMs relative
to sextupoles.
Hor. & Ver. Electrostatic
displacement monitor
•Electrostatic gauge was
attached to sextupoles in LER
local chromaticity correction
section to measure the BPM
displacement.
•Correction is added to BPM
reading to stabilize orbit
relative to sextupole center.
•Very good result.
•Necessary for all sextupoles in
future.
BPM
Sextupole
Quadrupole
M. Tejima, M. Arinaga, et al
•Must be compatible with
sextupole movers.
BPM gauge was effective to suppress the tune drift.
Disp. (mm)
v. Tune set
v. Tune measured
Before compensation
After compensation
Permanent magnets (“C-Yoke”) in LER
C-Yoke
•1,600 sets of C-Yokes were installed in LER t 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 were affected
by PS, probably through
magnetic flux change.
•Tunes of KEKB rings were
modulated.
•Improved by making the
power supplies’ response
faster, but…
Dny ~0.0033 (p-p)
Self oscillation of KEKB
quad power supply
•Later PS went shut down
by failure in the electromagnetic horn.
Tunes were modulated 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
H24
QC1RE QC2RP
QC2RE
H23
IP
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 (was 1650 mA
before).
•Operating at very bad current ratio degrades the specific luminosity.
•The bellows will be fixed during the winter shutdown.
Probably similar to the HER QC1LE Bellows Leak in March.
•
•
•
•
23日、ベローズを切断、予備を溶接。
フィンガーを固定していた金具(SUSリング)が外れていた。
金具は点付け４箇所。溶接が不十分？
Ｌ側でも一度経験。その後溶接箇所を増やした。
The RF contact was separated from the chamber.
“official” goal
1 /ab comes on the horizon!
44 /fb/mo
24 /fb/mo.
Crab Cavity
Beam Test
18 /fb/mo.
We are here
K. Hosoyama et al
Crab cavity production schedule （Nb coax）
FY 2004
4
1. 原型試験機
1) 成膜装置＆試験
2) 簡略同軸部
3) 同軸部
4) 入力結合器
5) クライオ＆チューナー
6 )全体組立
7) 低温試験
8) 高周波試験
2. 実用機＃１、２
1) 大臣特認（空洞）
2) 特定則（空洞）
3) 空洞成型
4) 空洞組立
5) 空洞表面処理
6) 空洞縦測定
7) 大臣特認（同軸部）
8) 特定則（同軸部）
8) 同軸部製作
9) 入力結合器
10) クライオ＆チューナー
11) 全体組立
12) 低温試験
13) 高周波試験
14) 据付
冷凍機関係
1) 冷凍機制御
2) トランスファーライン
3) 高圧ガス申請
RF吸収体関係
1) RF吸収体 f240, f188
2) 冷却水
横クライオ・テストスタンド
1) T.R.T
2) 大電力
5
6
7
8
FY 2005
9 10 11 12 1
2
3
4
5
#2
#1
#1
#2
7
8
9 10 11 12 1
空洞ジャケット溶接
#1
改造
6
EBW
冶具製作
Coax. coupler
ＲＦ試験
3
4
prototype
#2
#2
2
アニール EP2
ジャケット溶接
EP１
Nb材の手配が必要
KHK 申請（特認）
Real model
審議＆認許
バレル研磨
空洞形状
成型
型修正
KHK 申請（特認）
開先加工
EP1 EP2
審議＆認許
申請書まとめ
着手が必要
ジャケット溶接
アニール
EBW
縦測定
アニール
ジャケット溶接
製作/ EBW EP１ EP2
製作
エージング
製作工程は実用機＃１を示す
実用機＃２の工程は１～２ヶ月後
HPR
実機 #1
実機 #２
サマーシャットダウン
2台同時に据付
Install 1/ring
5
Crab Cavity & Coaxial Coupler
Top View
Input coupler
RF
Absorber
Bellows
I.D. 240
Stub
Support
RF
Absorber
Coaxial Coupler
I.D.100
Monitor Port
Liq. He
Liq. He
80 K LN2 Radiation Shield
Crab Mode
Reject Filter
C-band accelerating section
1. First prototype C-band
accelerating section was
fabricated and installed in
KEKB linac in 2003
summer.
2. RF pulse compressor was
installed in 2004 summer.
3. Achieved field gradient is
42 MV/m with 12 MW RF
power from Klystron with
pulse compression.
T. Kamitani, T. Sugimura, K. Yokoyama et al
S-band section
C-band section
RF pulse compressor
SKIP: SuperKEKB Injector Pulse-compressor
1. SLED-type pulse
compressor
(CERN-LIPS like TE038-mode)
2. Q0 = 132,000 (measured)
3. Coupling beta = 6.6
4. average power
multiplication ~ 3.4
5. Achieved power level
input RF power : 44 MW,
output RF power : 204 MW

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