Electron / Positron Injector Linac
K. Furukawa
for Linac division

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

Linac Overview

Linac in SuperKEKB Project! 40-times higher Luminosity"Twice larger storage beam Higher Linac beam current"20-times higher collision rate with nano-beam scheme#  Low-emittance Linac injection beam
#  Shorter storage lifetime
 Higher Linac beam current!Linac challenges

40xLuminosity"Low emittance e# High-charge RF-gun"Low emittance e+# Damping ringe+ increase"Higher e+ beam current# New capture section"Beam transport"Four ring manipulation
Linac Upgrade Status towards SuperKEKB

2x beamcurrent

RF-gunKazuro Furukawa, KEK, Jun.2012.

2Linac Overview

SuperKEKB Injector Linac! Higher Injection Beam Current" To Meet the larger stored beam current and shorter beam lifetime inthe ring" 4~8-times larger bunch current for electron and positron" Reconstruction of positron generator, etc! Lower-emittance Injection Beam" To meet nano-beam scheme in the ring
" Positron with a damping ring
" Electron with a photo-cathode RF gun" Emittance preservation by alignment and beam instrumentation! Quasi-simultaneous injections into 4 storage rings" SuperKEKB e–/e+ rings, and light sources of PF and PF-AR"Improvements to beam instrumentation, low-level RF, controls,timing, etc
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Linac Overview and Positron Capture

Linac and Positron Capture Section
SuperKEKB injector Linac
high currentgun
low emittanceRF gun
3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)50 Hz (e+ or e-)pulse-by-pulse
mode switching 1.1 GeV
Damping Ringcirc. 136 m

BunchCompressor

S-bandlinac

PF�

AR (later)

2.5 GeV e- 6.5 GeV e- 
0.1nC x 1LER, AR�Energy-spreadCompression System
3TRF gun

4.0 GeV e+ 4nC x 2ECSe+ target &L-band+LAS
capture section

C-bandmodules

7.0 GeV e5nC x 2HER�

Positron Capture Section
positron target relocation from 2-1 to 1-5
for energy margin in DR injection

DR

1-3 1-4 1-5 1-6 1-7 1-8 2-1 2-2 2-3 2-4 2-6 2-7 2-8solenoid

FODO singlet systemL-band LAS

normal S-band

targetLarge Aperture S-band

Linac Upgrade Status towards SuperKEKB

3-2

Q triplet 3m Q triplet 5m

Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

Design of Positron Capture Section
KEKB e+ capture section
$ QWT system (2.0 T x45mm+ 0.4 T x8m)
air-core pulse coil DC solenoids$ KLY1 (S-band) -> 2 x 1m 12 MV/m, aper 2a = 27 -> 25 mm$ KLY2 (S-band) -> 2 x 2m 10 MV/m, aper 2a = 25 -> 21 mm$ beam energy at capture section exit : 80 MeV
N(e+)/N(e-) = 10 % at 3.5 GeV linac-end
N(e+)/N(e-)/E(e-) = 2.5 %/GeV

SuperKEKB e+ capture section
$ AMD system (6.0 T x200mm+ 0.4 T x15m)
Deceleration mode
flux concentrator DC solenoids
full L-band configuration$ L-band-> 2 x 2m 10 MV/m, aper 2a = 39 -> 35 mm
LA S-band -> 4 x 2m 10 MV/m, aper 2a = 32 -> 30 mm$ beam energy at capture section exit : 110 MeV
L-band + LAS configuration
for comparable performanceN(e+)/N(e-) = 65 % at 1.1 GeV DRwith reduced costN(e+)/N(e-)/E(e-) = 19 %/GeV
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

5Positron Capture

Flux Concentrator BINP-type% In collaboration with BINP, prototype

field measurement & high-power
operation test performed at KEK fromNov. 2010 to March 2011.
% Breakdown issue with vacuum burst
above 7 Tesla was identified. However,
the investigation with BINP experts wasinterrupted by the Earthquake.

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

Flux Concentrator SLAC-type% with helps from SLAC and IHEP

we are going to fabricate SLACtype FC for linac commissioning
from 2013 autumn and stable
operation at T=0.
% Final optimization of field design
and mechanical design as well
as fabrication system design

SLAC-type FC at IHEPLinac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

Capture by L-band and LAS structures! L-band"Large aperture (d=39~35mm) of accel. structure isdesirable for transverse acceptance of Positron Capture
Section"Coprime (5:11) frequency relation is effective to sweep out
satellite bunches critical to DR radiation shield issue.
Full S-band (LAS) capture section gives comparable e+yield, but with plenty of satellite particles! LAS (Large Aperture S-band)"Medium large aperture (d=32~30mm) is desirable fortransverse acceptance of PCS and quad focusing system"Existing S-band rf source, SLED, DC solenoids are available& compact Q at FODO (reduction in initial cost)
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

8Positron CaptureL-band Klystron% 40 MW L-band(1298 MHz) klystron PV-1040

designed by KEK and Mitsubishi Electric% compatible with existing S-band modulator
and KLY tank in KEKB linac% first PV-1040 delivered in March 2010
% performance test since June 2011
% KLY operation spec. at SKB linac
30 MW x 1.5 us x 50 pps achieved !
% another two PV-1040 will be delivered,
we will have three L-band klystrons for(1) positron capture section(2) bunch compressor at DR(3) spare(KLY data byS. Matsumoto)�

Linac Upgrade Status towards SuperKEKBKazuro Furukawa, KEK, Jun.2012.

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Positron Capture

L-band Accelerating Structure% first L-band structure completed in March 2010
% operation test at test stand from April 2012
$ RF frequency 1298 (=2856 x5/11) MHz$ traveling-wave structure (short rf pulse)$ constant gradient$ (2/3)pi phase advance per cell
$ structure length 2.2 meter$ disk aperture 2a = 39.4 ~ 35.0 mm$ field strength 12 MV/m@15 MW input$ single feed coupler (with field symmetrized)$ attenuation constant tau = 0.26

(structure databy T. Higo)�
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

10Positron Capture

Built-in Collinear RF Power Load% L-band rf coupler limits DCsolenoid inner radius >= 180 mm% for regular cell region, the radius
can be 130 mm% with built-in collinear power load,
the output coupler can beomitted and end-tail becomes thin

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

Large Aperture S-band Structure! LAS structures are used," in second unit of capture section" in two accelerator modules just behind capture section! Large aperture and compact outer diameter" existing rf source available" existing DC solenoid available" compact quad outside LAS structure compared with L-band! Cost-performance balance$ traveling-wave structure$ constant gradient$ (2/3)pi phase advance per cell
$ structure length 2.2 meter$ disk aperture 2a = 31.9 ~ 30.0 mm$ field strength 16.4 MV/m with SLED
6.9 MV/m w/o SLED$ two port input coupler (J-shape side-couple)
two port output coupler (ordinary shape)$ attenuation constant tau = 0.112
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

12

Positron Capture

Solenoid Field Design% FC + DC solenoid field distribution determines transverse

acceptance of capture section and e+ initial emittance.

FC + DC Solenoid fieldpeak ~ 6 Tesla�

Linac Upgrade Status towards SuperKEKB

DC solenoid field(long range)�

Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

Particle Simulation% capture section : Zang Lei (GPT), T.Kamitani(EGS4, CST)
% linac 1~2 sector + LTR : T.Miura, N.Iida (SAD)% DR beam dynamics : H.Ikeda% RTL + linac 3~5 sector + BT-line : N.Iida (SAD)
Simulation
ExampleAcceleration phase modein capture section
Energy (MeV)

Energy (MeV)

from target tocapture section
exit (120 MeV)

Deceleration phase modein capture section

longitudinal position (mm)
Linac Upgrade Status towards SuperKEKB

longitudinal position (mm)
Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

ECS at LTR & BCS at RTL
Bunch
Compression
System�Energy-spread
Compression
System�BCS reduce bunch-lengthof e+ extracted from DRECS reduce energyspread of e+ entering DR

energy gradient by RF field+ non-isochronous arc

non-isochronous arc +energy correction by RF field
R56 = -0.61 m
Vc = 41 MV (S-band)
compression 1/3

Vc = 37 MV (L-band)
R56 = -1.05 m
compression 1/9�RTL�
Linac Upgrade Status towards SuperKEKBLTR�

schematic view!
scale is not precise !�

Kazuro Furukawa, KEK, Jun.2012.

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Positron Capture

Injector Positron Source Status! Fabricating SLAC-type FC for T=0! Need consideration on target protection! 1st L-band structure to be high-power tested soon
! Design of L-band collinear load fixed! Waveguides & loads in fabrication! L-band klystron 1st tube ready! Large Aperture S-band structures in fabrication! DC solenoid field dips are moderated by huge solenoids! Beam optical design almost OK! Particle tracking simulation is ongoing for e+ yield andhardware parameter optimization! Damping Ring, ECS, BCS are in construction
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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RF GunRF Gun at 32 unit for 5nC / 20mm-mrad
Emittance of 300µm in KEKB should be reduced to 20µm

Laser�
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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RF GunLaser Development!Oscillator"Nd:YAG medium, LD excitation"Change frequency from 114MHz to 52MHz#Synchronized through 10.39MHz Clock"Successful stable excitation!Amplifier improvements"~1.5mJ / 30ps / pulse at 266nm

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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RF GunLaser Amplifier Development�Output�R=0.5m!
f=250mm!

R=0.5m!
f=250mm!

Nd:YAG!

R=99%!
PD!

λ/4!

Linac Upgrade Status towards SuperKEKB

Input�

Kazuro Furukawa, KEK, Jun.2012.

RF GunLaser Amplifier Development
Multi-pass
Amplification
CleanerAmp.
withEO and AO
components

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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RF GunPhoto Cathode Development!Started with LaB6
"Successful up to ~0.3nC before April!Replaced with Ir5Ce"For better quantum efficiency"Achieved up to ~1nC / bunch in April!Surface cleaning cut & try"With high power laser with/without RF"LaB6 and Ir5Ce are rather stable!Other possibilities in the future"CsTe, etc
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

21

RF GunSlant Laser Injection! Perpendicular laser injection" Before May.2012! Slant laser injection through CaF2 windows" Non-zero perpendicular electric field (?)" Increased up to ~3nC / bunch" Emittance should be confirmed
Polarization dependence (Ir5Ce)�
(東工大/佐藤)�
1
0.8
Q/Qmax

0.6

0.4
0.2
002040 60 80 100 120 140 160 180
polarization angle (degree)

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

22

RF GunStable Operation of RF Gun
!DAW (Disk and washer) type photo cathode RFgun"Strong RF beam focusing"With stable cathode"Should experience
continuous PF injection
in autumn 2012
"With backup laser

Electric field and beam tracing simulation�
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Fast Recovery

Fast Recovery at Failure of Positron Generator! Positron capture section replacement"How components should be designed/installed in order to be
replaced under high radiation condition?
(replaced twice in KEKB)"Positron target,
Flux concentrator,
Bridge coil,Acceleration structure,Solenoid, Girders,
Vacuum components, etc.
"Large unit should be replacedwith special links"Under discussion

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Reliability with Energy Management

Reliability with Failed Acceleration Unit
!Linac Beam Energy Management"At least one backup acceleration unit should available
with two units for an energy knob in regions of ;#Before 180deg arc
before damping ringafter damping ring

"In each of electron and positron modes (and PF/PF-AR)"The plan was fixed"While troubles at several important units (like capturesection) can prevent operation, others should bebackuped
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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BPM

Beam Position Monitor Development!Requirement"50Hz with event synch., 2bunchs 96ns apart, 10micron
resolution, 0.1~10nC variation at 50Hz

!Present system"8bit oscilloscope, Windows-EPICS, 50Hz,"50~100micron resolution!BPM is essential for"Low-emittance transportwith wakefield compensation"Beam stability monitor

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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BPM

BPM Development! Modifications to commercial module Libera"Event-based control capability and embedded EPICS"Fast attenuator for variable beam modes"Modifications to filters and ADCs for 2-bunches 96ns apart! New development at local company"In VME form factor, with external CPU and event-based controls"Additional on-line pulse test capability
band-pass + saw filters�! Both evaluations in this year
"Lab tests during summer"Beam tests in autumn"Resolution, price, reliability,flexibility, manageability, etc"Installation in 2014
Linac Upgrade Status towards SuperKEKBKazuro Furukawa, KEK, Jun.2012.

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Four Ring Injection and PF Sync.

4 Ring Injection Timings!SuperKEKB will have integer RF clock relation
with Linac"Needs ring circumference compensation withfrequency modulation!PF / PF-AR will not have common clock with Linac"As they need independent circumferencecompensation"Linac injects beams at accidental synchronization"No synchronization opportunity if integer relation!Damping ring and L-band introduction"Requires further condition restrictions
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

28

Four Ring Injection and PF Sync.

PF Synchronization!PF Frequency modulation in a year"Approx. 2 x 10^-5Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Four Ring Injection and PF Sync.

Injection Synchronization with 114MHz
For PFwith KEKB
Duration Jitter
20ms+/-500μs
Clock Jitter
500 psPlot in 10-4
No problems

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Four Ring Injection and PF Sync.

Injection Synchronization with 10.39MHzFor PF with
SuperKEKB
Duration Jitter
20ms+/-500μs
Clock Jitter
500 psPlot in 10-4
Bad region
have to beavoidedLinac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Four Ring Injection and PF Sync.

Investigation!This issue is different than the bucket
selection challenges at SuperKEKB"Bucket selections both at DR and MR!Was not well investigated under 10.39MHz"May require pulse-to-pulse LLRF manipulation
between RF systems of PF / PF-AR / SuperKEKB"Should be investigated further

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Event System Development Collaboration with SINAP! For PLC (F3RP61 Linux CPU) as well as VME! Under testing! Many more synchronous controls
at a reduced cost

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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Facility

Facility for Electric Power and Cooling Water! Linac needs electricity and cooling water extensions, especiallyfor positron generator upgrade! First estimation was performed, and was found that it may impact
the construction! Under discussion how to extend the facility[I] 第1〜2セクター
陽電子ビーム強度の５倍化に向けて、収束用電磁石の数と強度が大幅に増加する。
増加分920 kVA, 900 L/min
現状 401kVA
1211 / 1430 L/min

Linac Upgrade Status towards SuperKEKB[II] 第3セクター
D R の 入 射 ＆ 出 射 路 の 新 設 に 伴 って、その電磁石の一部が入射器トンネルに新たに設置される。
増加分310 kVA
現状 6.7kVA
136 / 500 L/min[III] 第３スイッチヤード１）陽電子エネルギーの増大（3.5GeV→4GeV）に伴う偏向磁石系の電力増及び ２）RF偏向によるエミッタンスモニターの新設に伴って熱負荷が増大する。
増加分300 kVA, 460 L/min
現状 158kVA（587+α）/ 750 L/min

Kazuro Furukawa, KEK, Jun.2012.

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ScheduleSchedule! Summer 2012 : Alignment, SY3, 3T-gun, 32-gun! Autumn 2012 : 32-RF-gun, A1-gun(0.2nC)! Winter 2013 : SY2 / DR! Spring 2013 : A1-gun! Summer 2013 : Installation of many components! Autumn 2013 : e– then e+ commissioning"Half Linac: PF injection, Day: construction, Night: commissioning! Spring 2014 : Pulsed Quad, Steering, Alignment! Summer 2014 : Installation of remainings! Autumn 2014 : Possible ring injection (?)! Winter 2015 : DR then MR injection commissioning!…
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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KEKB

Summary

Change in Operation Modes at KEKB
Belle/KEK

May.2000
Apr.2003
Dual Bunch e+Feb.2005
Continuous
Injections
Dec.2008
Crab Cavities andSimultaneous Injection
Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

36

Thanks

Thank You for Your Patience�

Linac Upgrade Status towards SuperKEKB

Kazuro Furukawa, KEK, Jun.2012.

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