View
214
Download
0
Category
Tags:
Preview:
Citation preview
Recent Progress of SuperKEKB AcceleratorsMakoto Tobiyama
KEK Accelerator Laboratory
KEKB BxB FB
Antechamber with TiN coating to suppress electron cloud instability
Construct positron damping ring
Electron beam 2.6 A
Positron beam 3.6 A
40 times gain in luminosity with nano-beam, double beam current
Super-KEKB
Optimize beam optics for low emittance beam
Superconducting quadrupoles to shrink colliding beam at IP
Colliding bunches
for high-quality electron beam (HER)
Adaptic optics for higher positron yield
Replace LER dipoles with longer ones (0.82m->4.2m) to reduce emittance
Extend RF system for high beam current operation
Damping ring
Low emittance gun
Positron source
New beam pipe& bellows
Belle II
New IR
2
KEKB BxB FB
KEKB upgrade plan has been approved
The MEXT, the Japanese Ministry that supervises KEK, has announced that it will appropriate a budget of 100 oku-yen (approx $117M) over the next three years starting this Japanese fiscal year (JFY2010) for the high performance upgrade program of KEKB. This is part of the measures taken under the new "Very Advanced Research Support Program" of the Japanese government.
Council for Science and Technology in MEXT has announced that SuperKEKB project should be pushed forward with one of the highest priority.
MEXT is requesting construction budget of SuperKEKB to Ministry of Finance for FY2011 (40 oku-yen).
KEKB BxB FB
Major items to upgrade
LER– Energy 3.5 GeV -> 4 GeV– Replace ~110 dipole magnets in the arc
section from L=0.89m to 4.2m to reduce emittance (18 nm -> ~3 nm).
– Change the damping wiggler layout (shorten wiggler period).
– Reduce vertical crossing scheme at Fuji point to reduce vertical emittance.
– Replace most of the vacuum chambers with the new antechambers with TiN coating.
KEKB BxB FB
Major items to upgrade
IR– Much larger crossing angle (22mrad -
>83mrad)– New superconducting magnets around IP
(HER and LER independent). Might apply permanent quadrupole for LER
QC2– Optimization of the compensation solenoid.
– Fine tuning of higher-order components of superconducting magnets.
– Two family local chromaticity correction scheme for both HER and LER.
KEKB BxB FB
Major items to upgrade
HER – Energy 8 GeV -> 7 GeV– Lower emittance(24nm -> 5nm)– Keep present placement of the most of arc
magnets.– New antechamber , or keep present vacuum
chamber (not fixed yet). Positron damping ring and new
positron target.– 8nc/bunch, 2 bunch injection
New RF gun for electrons with reduced emittance.
KEKB BxB FB
Machine parameters
HER lattice
IP
herfqlc5210BX* 25 mmBY* 0.30 mm
RFRF
(wiggler) injection
beam
LER lattice
IP
lerfqlc_1352BX* 32 mmBY* 0.27 mm
wigglerRF
wiggler(RF)
RFRFinjection
beam
KEKB BxB FB
0.89 m dipole 4.2 m dipole
Replace 0.89m dipoles in the arc section with new 4.2m dipoles.
LER Low emittance lattice
KEKB BxB FB
Double the wiggler period by adding new wiggler poles.
KEKB SuperKEKB
11
Most of the Sextupoles, steering magnets will be replaced.
LER wiggler section
KEKB BxB FB
Collision parameter
LER HER
lerfqlc1351 herfqlc5210
X-Y Coupling and Dispersion at IR
X-Y Couplings(r1,r2,r3,r4) and vertical dispersion induced by the solenoid field are corrected between two sextupoles to correct chromaticity locally.The correction is done by a rotation of final quadrupoles, skew quadrupoles and/or vertical bending magnets.
KEKB BxB FB
LER
KEKB BxB FB
HER
2010/9/23 Updated QCS system 16
8 SC main qadrupoles (QC1RP, QC1RE, QC2RP, QC2RE, QC1LP, QC1LE, QC2LP, QC2LE)2 SC compensation solenoids52 SC correction coils
LER
HER
Configuration of IR magnet system
2010/9/23 Updated QCS system 17
IR magnets
QC2LE
QC2LP
QC1LE
QC1LP
QC1RP
QC1RE
QC2RP
QC2RE
Integral field gradient, (T/m)・m Position from IP, mm Magnet type
QC2RE 12.91 2925.0 S.C.
QC2RP 10.92 [31.21T/m*0.350m] 1936.1 S.C.
QC1RE 26.22 [72.91*0.360] 1390 S.C.
QC1RP 22.43 [75.61*0.297] 922 S.C.
QC1LP 22.91 [62.00*0.370] -922 S.C.
QC1LE 26.03 [72.38*0.360] -1390 S.C.
QC2LP 10.96 -1977.1 S.C.
QC2LE 14.13 -2900.0 S.C.
IRONIRONIRON
Magnet design (QC1RP and QC1LP)Same design of the cross section for QC1RP and QC1LP2 layer coils [double pancake type]Designed SC cable [under development]
Cable size : 2.5 mm in height, and 0.93 mm in widthSC strand cable : 0.5 mm, 10 wires in the cable
SC correctors inside of the magnet boreb4, a2, b1, a1 from the inside
Single layer coil
Beam pipe : warm tube, inner radius=10.5 mm2010/9/23 Updated QCS system 18
SC cancel correctors against the leak field from QC1Pb3, b2, b1 from the inside
Beam pipe : warm tube , inner radius=10.5 mm
e+e-
SC cancel correctorsb4, b3, b2, b1
SC correctorsb4, a2, b1, a1
QC1P
Design of IR SC magnets (QC1P)
2010/9/23 Updated QCS system 19
Compensation solenoidsBmax=4.10 TBmax=4.34 T
• Design of compensation solenoids – The solenoids are designed to be segmented into small coil pieces.– The coil pieces have decreased turns gradually along the distance from IP.– The electro-magnetic forces on the ESR and ESL are 29 kN and -18 kN, respectively.
• The field changes of the solenoid field are managed to be a half of the previous design.
• Fringe field influence on beam emittance is negligible by the beam simulation.
ESRESL
New IP chamber design
GdfidL model (cut model)
Type C Type D
Loss_z : (x,y) = (0,0)
Type C_HER Type D_HER
Loss_z : (x,y) = (0,0)
Type C_LER Type D_LER
KEKB BxB FB
KEKB-ARES Nomalconducting cavity
KEKB Superconducting cavity
RF systems (in the tunnel)
We will continuously use those cavities with small change, such as change of coupling.
24
KEKB BxB FB
RF systems (grand level)
Add 7 (or 9) RF stations for higher beam loading from 25 stations to 32 (or 34) stations.
Introduce digital low level RF system for much fine tuning..
1.2MW CW klystronHigh power RF system
25
Design of main components_1
Beam pipes: beam pipes with ante-chambers– Low beam impedance
∵ Pump ports and SR masks locate in an antechamber.– Reduction of SR power density is not a main purpose now.– The cross section should fit to the existing magnets.– LER:
An effective countermeasure against the electron cloud. Aluminum alloy is now available for arc section. Copper is required for wiggler sections due to high SR power.
– HER: Copper is required due to high SR power.
2010/8/6 KEK - BINP Meeting 26
BeamSR
NEG strip Concept
Pump (NEG) is installed into one of the ante-chamber (inside of the ring)– Distributed pump system for
effective pumping. S ~ 80 l/s/m.– Inserted from end flanges.
Design of main components_2 R&Ds of beam pipes_1
– Copper beam pipes with antechambers have been installed into the LER, and tested with beams.
– Cold drawing method for copper pipe was established.
2010/8/6 KEK - BINP Meeting 27
Straight duct
BPM
Bent duct
Wiggler section
Arc section
Design of main components_3
R&Ds of beam pipes_2– Tests of the extrusion of aluminum-alloy beam pipes are under going
for LER.
2010/8/6 KEK - BINP Meeting 28
Aluminum-alloy duct Aluminum-alloy duct
110
Example of cross section of HER beam duct
– The design of HER beam pipe has not yet fixed.
Fit to existing magnets. If the half-aperture is ~90 mm
the SR power is the same level as the present HER.
Design of main components_4
LER: More powerful countermeasures against the electron cloud effect is required.
2010/8/6 KEK - BINP Meeting 29
Sections L [m] L [ %] Countermeasure Material
Total 3016 100
Drift space (arc) 1629 m 54 TiN coating + Solenoid Al or Cu
Steering mag. 316 m 10 TiN coating + Solenoid Al or Cu
Bending mag. 519 m 17 TiN coating + Grooved surface Al
Wiggler mag. 154 m 5 Clearing Electrode Cu
Q & SX mag. 254 m 9 TiN coating Al or Cu
RF section 124 m 4 (TiN coating +) Solenoid Cu
IR section 20 m 0.7 (TiN coating +) Solenoid Cu
With these countermeasures, the average electron density of 1E11 e-/m3 will be obtained.
Cloud density simulation / experiment Blue: CLOUDLAND simulation
– max=1.2, Effect of antechamber has been estimated by setting the photoelectron yield to 1/10 (0.01). Effect of clearing electrode and the groove has been estimated by the experimental result.
Red: Experimental result using KEKB LER Yellow: with TiN coating
Single Bunch Instability Threshold (~1x1011)
With TiN coating
Condition ne [m-3]
Circular Cu chamber[KEKB beam pipe]
5.2E12
Antechamber (1/4) 1.1E11
Solenoid at Drift (1/50) 4.7e11
Solenoid at Drift (1/50) +Cu Antechamber (1/4)
9.4E105.7e10
+Electrode in Wiggler (1/100) 5.84e10
+Electrode in Wiggler (1/100) +Groove in B (1/10)
2.7E101.7e10
Design of main components_5
Some R&Ds for EC mitigation Clearing electrode for wiggler section.
– Manufacturing has already started.
2010/8/6 KEK - BINP Meeting 31
Inside view
Grooved surface for bending magnets section– Extrusion test of aluminum beam pipe is undergoing.
Design of main components_6
Flange : MO-type Flanges– Thermally strong, sure RF bridge, applicable to ante-
chamber scheme, low beam impedance– In addition to SS flanges, copper alloy and aluminum-
alloy flanges has been developed. Easy welding to pipes, reduction in heating by joule loss
– Several flanges have been installed into the ring and tested.
2010/8/6 KEK - BINP Meeting 32
Cu-alloy flange (CrZrCu) Al-alloy flange (A2219, A2024)
Design of main components_7
Bellows and gate valves with comb-type RF-shield– Sure RF shielding, thermally strong– Applicable to ante-chamber scheme – Finger-type for some cases, if flexibility is required.
Trial modes has been installed into the ring and tested.– Reduction in the temperature of bellows has been
demonstrated. Aluminum RF shield is under study for
aluminum bellows chambers.
2010/8/6 KEK - BINP Meeting 332010/2/17
Bellows chamber (by BINP) RF-shield (gate valve)
Gate valve
SuperKEKB Injector Linac Parameters
KEKB (e+/e-)achieved
SuperKEKB (e+/e-)required
beam energy 3.5 GeV / 8.0 GeV 4.0 GeV / 7.0 GeV
stored current 1600 mA / 1200 mA 3600 mA / 2620 mA
beam lifetime 150 min / 200 min 10 min / 10 min
bunch charge 10 -> 1.0 nC / 1.0 nC 10 -> 4.0 nC / 5.0 nC
# of bunches 2 / 2 2 / 2
beam emittance ()[1 2100 m / 300 m 43 m / 20 m
energy spread E/E 0.125 % / 0.05 % 0.46 % / 0.08 %
bunch length z 2.6 mm / 1.3 mm 6.05* mm / 1.3 mm
*(assuming bunch compression after DR)
primary e– e+ e+primary e– e– e–
34
AB
C 1 2 3 4 5
KEKB e+
for LER3.5 GeV1nC x 2
4.0 GeV10nC x 2
ECS (Energy-spreadCompression System)
e+ target &S-band capture section
A1 gun
Accelerate e- (primary) beam to 4GeV, inject positron target.
Conversion efficency~1/10
Need to accelerate 10 times larger primary beam.
Accelerate positron up to 3.5GeV
AB
C 1 2 3 4 5
SuperKEKB e+ Positron damping ringto reduce emittancePrimary electron beam
(10nC)
Positron Linac
for LER4.0 GeV4nC x 2
3.5 GeV10nC x 2
1.1 GeV @DR
ECS (Energy-spreadCompression System)
A1 gun
C-bandmodule x 2
e+ target, matching dev. &L-band capture section
ECSBCS
L-band acceleration section and new matching device after target C-band Acceleration units
(2 units)
35
AB
C 1 2 3 4 5
KEKB e–
for HER8.0 GeV1nC x 2
1.7 GeV @J-arc
target bypassbump orbit
A1 gun
3T gunmoved from CT
C-bandmodule
for PF2.5 GeV0.1nC x 1
for AR3.0 GeV0.1nC x 1
Accelerate e- beam up to 8GeV using all the units of the linac
Pulse bump + hole on target to bypass positron target
Pulse by pulse energy control (for PF)
AB
C 1 2 3 4 5
SuperKEKB e–Low emiitance RF gun for HER(5 nC)
for HER7.0 GeV5nC x 2
1.7 GeV @J-arc
target bypassbump orbit
RF gun
e- bypass line for DC separation bend
for PF2.5 GeV0.1nC x 1
Electron linac
36
Damping Ring Layout
Electron gun
e+ target
parameters value
Beam energy 1.1GeV
# of bunches 4
Bunch charge 4 nC (max.8 nC)
# of bunch trains 2
max. stored current 35 mA (max.70 mA)
Emittance (injected) 1700 nm (normalized)
Emittance (extracted) 42.5 nm (normalized)
Damping ring is necessary to inject the positron beamto SuperKEKB LER (due to smaller physical and dynamic aperture)
37
KEKB BxB FB
Beam instrumentation
New BPM chamber with flange-connection BPM heads.
New 508MHz narrowband detectors(VXI) Medium-band position detectors for fast
orbit feedback– Especially around IP and local chromaticity correction
region– Orbit function (phase advance, XY coupling)
measurement using pilot bunch during collision. X-ray bunch-by-bunch beam size monitor
– CesrTA (KEK, Cornell Univ., Hawaii Univ.)
KEKB BxB FB
Impedance/button output simulation
-40
-30
-20
-10
0
10
20
30
0 0.5 1 1.5 2
Out
put
(V/m
A)
Time(ns)
(A)Time-domain response
10-17
10-16
10-15
10-14
0 5 10 15 20 25 30
Am
plu
tud
e
Frequency(GHz)
(B)Ampliutude spectrum
KEKB BxB FB
Beam signal
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 2 4 6 8 10 12 14 16
Out
put
(V)
Time(ns)
Temperature rise ~3deg @ 1.6A
KEKB BxB FB
Digitex 17K94A 509MHz detector
4:1MUX
18bit ADC (AD7690)
Direct downconverter with image rejection
CPLD(VXI control)
SHARC(21369)DSP
KEKB BxB FB
SuperKEKB BxB feedback
We need to – prepare longitudinal feedback systems on both rings.– improve the performance of the transverse feedback
systems– design and prepare much durable vacuum components
such as BPM electrode or feedback kickers to stand higher beam current..
Use general purpose feedback signal processing system– iGp or iGp12
Development of BPM electrode with improved time response using glass-type seal
Development of better bunch detection circuit
KEKB BxB FB
SuperKEKB Transverse FB plan
KEKB BxB FB
SuperKEKB Longitudinal FB plan
FY2009 FY2010 FY2011 FY2012 FY2013 FY2014
Beam pipes (LER_arc)
Beam pipes (HER)
Beam pipes (LER_wiggler)
Magnets & Power supplies
Tunnel clear
Beam monitors and Control
IR hardware
RF system
FabricationFabricationTiN coatingTiN coating
InstallInstall
FabricationFabricationTiN coatingTiN coating InstallInstall
Remove magnets and beam pipes
Remove magnets and beam pipes Base
platesBase
plates
FabricationFabricationInstallInstall
Design / FabricationDesign / FabricationField measurementField measurement
InstallInstallCabling / CheckCabling / Check
AlignmentAlignment
Layout change / Add stations / Cavity improvementsLayout change / Add stations / Cavity improvements
Design & FabricationDesign & Fabrication
MR commissioningBeam operation
DesignDesign
DesignDesign
ConditioningConditioning
TestTest
SuperKEKB Main Ring schedule Jul. 30, 2010
Infrastructure Building construction Building construction Cooling systemCooling system
QCS prototype QCS prototype QCS fabricationQCS fabrication
Install & testInstall & test
45
InstallInstall
Beam pipes
B&Q mag. design/fabricateB&Q mag. design/fabricate
InstallInstall
Magnets & Power supplies
FY2009 FY2010 FY2011 FY2012 FY2013 FY2014
align.align.
Tunnel construction Tunnel construction
RF System
MR constructionMR constructionBeam operation
Injector upgrade and DR construction schedule
Other magnetsOther magnets
Tunnel & building
Design Design
Building construction Building construction
Base plan Base plan
cavity designcavity designcavity fabricationcavity fabrication cavity installcavity install
HP&LLRF installHP&LLRF install
InstallInstall
Monitors, Control
FabricationFabrication
FabricationFabrication
MR commissioning
RF-gun & laser system
e+ new matching & L-band acc. R&D R&D
Construction Construction
Design studyDesign studyCommissioning at test standCommissioning at test stand
e- beam commissioninge- beam commissioning
move to A1move to A1
e+ beam commissioninge+ beam commissioning
Damping Ring
Linac
Main Ring
HP testHP test
Power suppliesPower suppliesField measurementField measurement
DR commissioning
A1 galleryextension A1 galleryextension
Jul. 30, 2010
46
KEKB BxB FB
Starting removing LER vacuum chambers
Most of the LER bending magnets will be removed (and discarded) within this fiscal year.
KEKB BxB FB
Open Quads, removing LER vacuum chambers
KEKB BxB FB
Belle will be rolled-out in Oct.
KEKB BxB FB
Summary
KEKB upgrade (to SuperKEKB) has been approved. Design work is still in progress
– Found optics parameters with large enough dynamic aperture in both HER and LER.
– Hardware design around IP including installing/removal method are settling.
We have now reliable parameter set for L=8E35cm-2s-1
Construction of new components for SuperKEKB have been started.– LER wiggler chambers will be delivered within this year.– Most of magnets of the positron damping ring will be delivered by
Mar/2011.– Bid for LER vacuum chambers (totally ~2km) and LER bending
magnets and other components will be made soon. Removal work (LER vacuum chamber, magnets, IR) has
been started
KEKB BxB FB
ばっくあっぷ
HER Wiggler
Quads are replaced by LER wiggler quads.L = 1m -> 0.46 m
herfqlc5215
herfqlc5214herfqlc5210
6/10
Fullwigglers:7.6 mrad
Machine Parameters (1)2010/Sept/82010/Sept/8 LERLER HERHER unitunit commentcomment
wigglerwiggler Full None
EE 4.000 7.007 GeV
II 3.6 2.6 A
Number of bunchesNumber of bunches 2,500
Bunch CurrentBunch Current 1.44 1.04 mA
CircumferenceCircumference 3,016.3700 m
εεxx/ε/εyy 3.2(1.9)/8.64(2.8) 5.3(5.2)/12.7(4.2) nm/pm ():zero current
CouplingCoupling 0.27 0.24 includes beam-beam
ββxx*/β*/βyy** 32/0.27 25/0.30 mm
Crossing angleCrossing angle 83 mrad
ααpp 3.49x10-4 4.55x10-4
σσδδ 8.00(7.66)x10-4 5.85(5.78)x10-4 ():zero current
VVcc 9.4 12.4 MV
σσzz 6.0(5.0) 5.0(4.9) mm ():zero current
ννss -0.0256 -0.0254
ννxx/ν/νyy 44.53/43.57 45.53/43.57
UU00 1.87 2.07 MeV
ττx,yx,y/τ/τss 43.0/21.5 68.2/34.1 msec
ξξxx/ξ/ξyy 0.0028/0.0894 0.0012/0.0807
LuminsoityLuminsoity 8x1035 cm-2s-1
herfqlc5210lerfqlc1351
Machine Parameters (2)2010/Sept/82010/Sept/8 LERLER HERHER unitunitwigglerwiggler Full 6/10
EE 4.000 7.007 GeV
II 3.6 2.6 A
Number of bunchesNumber of bunches 2,500
Bunch CurrentBunch Current 1.44 1.04 mA
CircumferenceCircumference 3,016.3704 m
εεxx/ε/εyy 3.2(1.9)/8.64(2.8) 4.6(4.5)/12.9(3.6) nm/pm ():zero current
CouplingCoupling 0.27 0.28 includes beam-beam
ββxx*/β*/βyy** 32/0.27 25/0.30 mm
Crossing angleCrossing angle 83 mrad
ααpp 3.49x10-4 4.55x10-4
σσδδ 8.00(7.66)x10-4 6.35(6.29)x10-4 ():zero current
VVcc 9.4 14.7 MV
σσzz 6.0(5.0) 5(4.9) mm ():zero current
ννss -0.0256 -0.0277
ννxx/ν/νyy 44.53/43.57 45.53/43.57
UU00 1.87 2.43 MeV
ττx,yx,y/τ/τss 43.0/21.5 58.0/29.0 msec
ξξxx/ξ/ξyy 0.0028/0.0874 0.0012/0.0807
LuminsoityLuminsoity 8x1035 cm-2s-1
herfqlc5214
Machine Parameters (3)2010/Sept/92010/Sept/9 LERLER HERHER unitunitwigglerwiggler Full Full
EE 4.000 7.007 GeV
II 3.6 2.6 A
Number of bunchesNumber of bunches 2,500
Bunch CurrentBunch Current 1.44 1.04 mA
CircumferenceCircumference 3,016.3707 m
εεxx/ε/εyy 3.2(1.9)/8.64(2.8) 4.3(4.1)/13.3(3.2) nm/pm ():zero current
CouplingCoupling 0.27 0.31 includes beam-beam
ββxx*/β*/βyy** 32/0.27 25/0.30 mm
Crossing angleCrossing angle 83 mrad
ααpp 3.49x10-4 4.54x10-4
σσδδ 8.00(7.66)x10-4 6.59(6.54)x10-4 ():zero current
VVcc 9.4 15.8 MV
σσzz 6.0(5.0) 5(4.9) mm ():zero current
ννss -0.0256 -0.0287
ννxx/ν/νyy 44.53/43.57 45.53/43.57
UU00 1.87 2.67 MeV
ττx,yx,y/τ/τss 43.0/21.5 52.8/26.4 msec
ξξxx/ξ/ξyy 0.0028/0.0869 0.0012/0.0807
LuminsoityLuminsoity 8x1035 cm-2s-1
herfqlc5215
KEKB BxB FB
IR geometry
KEKB BxB FB
LER
KEKB BxB FB
QC1RE
QC1RP+corr. coil
QC1LP+corr. coil
QC1RE+corr coil
QC1LE+corr. coil
QC2LPPM
QC2RP+corr. coil
QC2LEPM
QC2REPM
Anti solenoid-L
Anti solenoid-RCryostat
Cryostat
IP
Interaction Region58
KEKB BxB FB
KEKB BxB FB
KEKB BxB FB
KEKB BxB FB
KEKB: One klystron supplies microwave to two ARES cavities
SuperKEKB: One klystron supplies microwave to One ARES cavity
• Multiply RF stations•Remove several ARES cavities
62
KEKB BxB FB
Outlook
Introduction Beam optics Interaction Region Vacuum system Beam monitor, bunch feedback Positron damping ring Dismantle and Construction schedule
KEKB BxB FB
Specific Luminosity vs FB Gain
+3 -30 +1.5
+3+3
+3
-2 -1
FB gain of the LER vertical affects the specific luminosity. The other gains (LER H, HER H/V) have no effect.
KEKB BxB FB
MD with Gproto (KEKB-LER)
Single beam – Vertical beam size increased with vertical feedback
gain– with fairly slow rise. Collision
– Vertical beam size jumped up with vertical feedback gain. Very strong dependence. Luminosity decreases around 10-20%.
2.5
3
3.5
4
4.5
5
5.5
0.45 0.5 0.55 0.6 0.65 0.7
CollisionSingle beam
Ver
tical
bea
m s
ize(
m) at
col
lisio
n po
int
Feedback Gain
KEKB BxB FB
Beam noise due to feedback system
Occasionally found the excess of vertical feedback gain of KEKB-LER increased the vertical beam size, decreased luminosity. – We had struggled with rather lower luminosity since
winter shutdown of 2005. During winter shutdown, I’ve replaced LO amplifiers– that made the gain of the front-end much higher than before.
– Occasionally, one stripline electrode of the LER transverse kicker failed (ground-contacted at downstream port). The corresponding transverse feedback amplifier failed due to reflection.
– The luminosity jumped up, and the vertical beam size of LER reduced!
KEKB BxB FB
180 180
AR 250A250 250W amp.
40cm wideband kicker
sumsum
0iso
0
180
0
180
0
sumsumTune X excite
509MHz
DC OFFSET
Vector1
4xRF750MHz
750MHz
BPM(Downstream)
iso
2 Tap FIR Filter
4xRF
BPM(Upstream)
From verticaldetector
Beam
Vector2
KEKB Transverse Bunch Feedback System
DC OFFSET
Present status and plans_1
R&Ds of components have almost finished.– For both copper and aluminum
The choice of material for LER beam pipe (arc section) is under discussion.– Strategy of radiation shielding is now a key point– The material will be (should be) fixed in these months.
2010/8/6 KEK - BINP Meeting 68
Manufacturing of some beam pipes has started. Beam pipes with clearing electrode for LER wiggler
section is under manufacturing (~180 m). – They will be delivered this autumn.– Together with corresponding bellows chambers
Beam pipes and bellows chambers for LER arc sections will be ordered this year.– The detailed design and the specification are now under
consideration.
KEKB BxB FB
BPM Head
KEKB BxB FB
HFSS/GdfidL simulation
-140
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20
S21(mode 1)
S21(mode 2)
S21(mode 3)
S2
1(d
B)
Frequency(GHz)
(A)SuperKEKB
-40
-30
-20
-10
0
10
20
30
0 0.5 1 1.5 2
Out
put
(V/m
A)
Time(ns)
(A)Time-domain response
10-17
10-16
10-15
10-14
0 5 10 15 20 25 30
Am
plu
tud
e
Frequency(GHz)
(B)Ampliutude spectrum
KEKB BxB FB
Loss factor
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
2 3 4 5 6 7 8
440 BPMs
Loss
fact
or(
V/p
C)
with
440
LE
R B
PM
s
Bunch length(mm)
KEKB BxB FB
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 2 4 6 8 10 12 14 16
Out
put
(V)
Time(ns)
KEKB BxB FB
• Mesh size 0.2mm• length 50mm, width 111mm, heigth 109mm(1/4 model)• bunch length 6mm or 5mm
KEKB BxB FB
Button output
-40
-30
-20
-10
0
10
20
30
0 0.5 1 1.5 2
Out
put
(V/m
A)
Time(ns)
(A)Time-domain response
10-17
10-16
10-15
10-14
0 5 10 15 20 25 30
Am
plu
tud
e
Frequency(GHz)
(B)Ampliutude spectrum
KEKB BxB FB
Wake (loss factor =0.16mV/pC)
KEKB BxB FB
Coupling impedance
-1
-0.5
0
0.5
1
1.5
2
2.5
0 2 4 6 8 10 12 14 16
ReZImZ
Impe
dan
ce(
)
Frequency(GHz)
-1
-0.5
0
0.5
1
1.5
2
2.5
12 13 14 15 16
ReZImZ
Impe
dan
ce(
)
Frequency(GHz)
y = M1/(1+M2*M2*(M3/X -X/M3)...
ErrorValue
0.0403741.9944m1
1.093238.118m2
0.003898414.68m3
NA0.88574Chisq
NA0.98283R
y = -M1*M2*(M3/X-X/M3)/(1+M2...
ErrorValue
0.041816-1.988m1
1.219938.454m2
0.004017714.682m3
NA0.94251Chisq
NA0.98428R
• 14GHz付近共振を fit• Rsh~ 2Ω、• Q~ 38• fc~ 14.68GHz
KEKB BxB FB
0 10 20 30 40 50 60 70 80 90 1000
1
2
3
4
5
6
7
8
9
Mode ID
Gro
wth
Rat
e (1
/s)
•最悪でも成長の時定数は 160ms程度:進行方向放射減衰時間よりずっと長い
•現 N型電極だと、成長の時定数が 7ms程度で危険
KEKB BxB FB
Beam signal
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 2 4 6 8 10 12 14 16
Out
put
(V)
Time(ns)
Temperature rise ~3deg @ 1.6A
KEKB BxB FB
Beam Instrumentation (1)
Slow bpm system– Development of 508.8MHz RF detector for COD
measurement Replacement of present 1GHz system (by HP) 1:4 multiplexer VXI-C size
KEKB BxB FB
HP43591A RF Detector
•4:1 MUX•Direct down convert 1GHz component to baseband with image rejection circuit•FFT the data using DSP (Motorola 96002 clock 40MHz)
248FFT=20ms(2048turn data acq.) + 10ms(FFT on DSP)
KEKB BxB FB
Beam Instrumentation (2)
Fast position detector for IR position feedback– Downcovert 508.8MHz component of the beam to
lower frequency with analog mixer, convert to digital signal, then detect position through digital filters (CIC+FIR)
Complicated analog RF circuit Not so sensitive with residual phase jitter of LO
frequency
KEKB BxB FB
Beam Instrumentation (3)
Medium band beam position detector with gated turn-by-turn position detector– Directly detect 508.8MHz component of the beam
with IF-sampling ADC (with lower frequency), then detect position through digital filters (CIC+FIR)
– Independent L/R detector with fast gate switch (<6ns)
Sensitive with residual phase jitter of LO Rather simpler circuit.
KEKB BxB FB
Mid-band system (Analog part)
KEKB BxB FB
Mid-band system (digital)
KEKB BxB FB
Evaluation circuit with Virtex5
Recommended