Recent Progress of SuperKEKB Accelerators Makoto Tobiyama KEK Accelerator Laboratory

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


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


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


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)


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.


Straight duct

BPM

Bent duct

Wiggler section

Arc section


R&Ds of beam pipes_2– Tests of the extrusion of aluminum-alloy beam pipes are under going

for LER.


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.


LER: More powerful countermeasures against the electron cloud effect is required.


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


Some R&Ds for EC mitigation Clearing electrode for wiggler section.

– Manufacturing has already started.


Inside view

Grooved surface for bending magnets section– Extrusion test of aluminum beam pipe is undergoing.


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.


Cu-alloy flange (CrZrCu) Al-alloy flange (A2219, A2024)


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






ββxx*/β*/βyy** 32/0.27 25/0.30 mm


ααpp 3.49x10-4 4.55x10-4


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


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






ββxx*/β*/βyy** 32/0.27 25/0.30 mm


ααpp 3.49x10-4 4.54x10-4


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


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.


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)


10-17

10-16

10-15

10-14

0 5 10 15 20 25 30

Am

plu

tud

e

Frequency(GHz)


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)


10-17

10-16

10-15

10-14

0 5 10 15 20 25 30

Am

plu

tud

e

Frequency(GHz)


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


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


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

Documents

Recent Progress of SuperKEKB Accelerators Makoto Tobiyama KEK Accelerator Laboratory