Progress of Injector Linac
Kazuro Furukawa
for Injector Linac

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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!概要!Alignment!電子銃!RF 電子銃!熱電子銃!陽電子発生装置!Schedule

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Linac Upgrade Overview

Mission of electron/positron Injector in SuperKEKB! 40-times higher Luminosity"Twice larger storage beam
# Higher beam current at Linac"20-times higher collision rate with nano-beam scheme$ # Low-emittance even at first turn
$ # Shorter storage lifetime# Low-emittance beam from Linac# Higher Linac beam current!Linac challenges"Low emittance e$ with high-charge RF-gun"Low emittance e+$ with damping ring"Higher e+ beam current$ with new capture section"Emittance preservation$ with precise beam control"4+1 ring simultaneous injection
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Linac Upgrade Overview

電子ビームパラメタ
SuperKEKB

KEKB

エネルギー (GeV)

7.08.0

HER蓄積電流値 (A)2.61.1

HERビーム寿命 (min.)6200最大ビーム繰り返し (Hz)5050

最大バンチ数 (rfパルス当たり)

22

エミッタンス (mm⋅mrad)50/20 (Hor./Ver.)100

バンチ電荷量 (nC)51

エネルギー広がり (%)

0.10.05

バンチ長 σz (mm)

1.3

1.3

ダンピングリングn/an/a同時トップアップ入射

4 rings (SuperKEKB
e-/e+, PF, PF-AR)

3 rings (KEKB e-/e+, PF)

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

Linac Upgrade Overview

陽電子ビームパラメタ
SuperKEKB

KEKB

エネルギー (GeV)

43.5

LER蓄積電流値 (A)

3.6

1.6

LERビーム寿命 (min.)6133

最大ビーム繰り返し (Hz)5050

最大バンチ数 (rfパルス当たり)

22

エミッタンス (mm⋅mrad)

100/20 (Hor./Ver.)2100

バンチ電荷量 (nC)

41エネルギー広がり (%)

0.1

0.125

バンチ長 σz (mm)

0.7

2.6

ダンピングリング〇n/a

同時トップアップ入射

4 rings (SuperKEKBe-/e+, PF, PF-AR)

3 rings (KEKB e-/e+, PF)

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB (1)! High-charge low-emittance RF gun development"QTWSC cavity and Ir5Cephoto cathode works well

Quasi traveling wave
side couple cavity

Ir5CeCathode! Positron generation confirmation for the first time
"Good agreement withthe simulation results

Positron generator

Signal fromprimary electron

Signal from positronwith opposite polarity! Precise alignment for emittance preservation"Recovering after earthquake"Reaching specification of 0.3mm! Utility upgrade during summer 2014
" for electricity (+1.5MW) and cooling water (+1400L/min)
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Linac Upgrade Overview

Linac Upgrade Progress towards SuperKEKB (2)! High power modulator upgrades! Low-level RF controls/monitor" Pulse-to-pulse modulation (PPM) between 4+1 rings" More spaces for increased number of devices! Beam instrumentation" Large/small aperture beam position monitors (BPM)" Precise/fast and synchronized BPM readout system" Wire scanners and beam loss monitors" Streak cameras" (Deflectors, etc)

! Event timing control system" Combination of MRF and SINAP modules" Essential for PPM operation" Precise timing & synchronized controls" Bucket selection at DR and MRSINAP event modules

Linac Upgrade Progress towards SuperKEKB

Beam wire scanner

K.Furukawa, KEK, Jun.2015.

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AlignmentAlignment

Linac Upgrade Progress towards SuperKEKBK.Furukawa, KEK, Jun.2015.

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Alignment

Alignment! High-precision alignment was not necessary in PF and KEKB
injections, and it was much damaged by earthquake in 2011.
! Instead of flexible-structure girder before earthquake, rigidstructure was adopted with jack-volts and fixed supports.
! Reflector pedestals are developed and mounted onto quadmagnets and accelerating cavities for laser-tracker measurement.
! Iterative measurement and adjustment with 500-m straight laserand position sensors should enable 0.3-mm global alignment.
! Laser tracker should enable 0.1-mm measurement within 10-mgirder unit.
! Displacement gauges, hydrostatic leveling, inclinometer are also
employed.
! Remote measurement system and girder mover system will benecessary for longer term, and are under development.
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

13

Alignment

Emittance Preservation and Alignment! If Device is off center of the beam
" Focusing magnet (quad) kicks the beam bunch" Accelerating structure (cavity) excites wakefield, to bend the tail! Distorted bunch in banana shape" Emittance dilution or blow-up, even 100 times larger$ Depending on the beam optics and the beam charge! Alignment and orbit correction is crucial to preserve theemittance
Sugimoto et al.

BeamFocusing
MagnetAcceleratingStructure
Transverse beam distribution in time direction

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

14

Alignment

Emittance Preservation! Offset injection may solve the issue! Orbit have to be maintained precisely! Mis-alignment should be <0.1mm locally, <0.3mm globally
Mis-alignment leads to Emittance blow-up

Orbit manipulation compensates it

100 samples
Sugimoto et al.
Linac Upgrade Progress towards SuperKEKBK.Furukawa, KEK, Jun.2015.

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Alignment

Alignment progress in 2014
! For the first time after earthquake at downstream sectors! Several measurements during summer! Measurement reproducibility was confirmed up to ~0.2 mm! While there existed
several conflicting
measurements,consistent scheme~5mm
has been established! Movement of tunnel
by several 10’s ofmicrometer wasobserved (→ mover)~10mm! Further work necessary
in 2015, for alignmentand girder replacement
Linac Upgrade Progress towards SuperKEKB

Higo et al.

K.Furukawa, KEK, Jun.2015.

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Alignment

Recent 500-m alignment over C-5after completion of initial alignment in late Jan. 2015

Linac Upgrade Progress towards SuperKEKB

Higo et al.

K.Furukawa, KEK, Jun.2015.

14

Alignment

Hardware alignment on girders in sectors 3~5Horizontal
VerticalHigo et al.

Horizontal
σ=34µmLinac Upgrade Progress towards SuperKEKB

Vertical
σ=47µmK.Furukawa, KEK, Jun.2015.

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Alignment

Floor vertical movement
in a half year from summer to winter

C311

Linac Upgrade Progress towards SuperKEKB

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28

38

Higo et al.

48

K.Furukawa, KEK, Jun.2015.

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Alignment

Estimation of floor movement
some typical observed values
Horizontal

VerticalDaily

0.10.1Week

0.10.1

Half a year

0.52Speed

0.01mm/hour

0.01mm/hour

Unit mm

We should study/develop the linac systemwith these values in mind.
Precise beam orbit control is necessary
to preserve emittance
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

24

RF gun

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

25

RF gun for low-emittance electron

RF-Gun development strategy for SuperKEKB! Cavity : Strong electric field focusing structure"Disk And Washer (DAW)=> 3-2, A-1(test)"Quasi Traveling Wave Side Couple=> A-1=> Reduce beam divergence and projected emittance dilution! Cathode : Long term stable cathode"Middle QE (QE=10-4〜10-3 @266nm)"Solid material (no thin film) => Metal composite cathode=> Started from LaB6 (short life time)=> Ir5Ce has very long life time and QE>10-4 @266nm! Laser : Stable laser with temporal manipulation"LD pumped laser medium => Nd / Yb doped"Temporal manipulation => Yb doped=> Minimum energy spreadLinac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

RF gun for low-emittance electron

Photo cathode RF gun development

Cascaded frequency doublers
Yb fiber and Yb:YAG think disk laser

Quasi traveling wave side couple cavity

Ir5Ce
CathodeIr5Ce photo cathode
Linac Upgrade Progress towards SuperKEKB! 5.6 nC / bunch was confirmed! Next step: 50-Hz beam generation &Radiation control
K.Furukawa, KEK, Jun.2015.

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Schedule• These*few*months:*Yoshida et al.

– Reconﬁgure*thermal*gun*for*positron*genera9on*– Step%by%step%RF+Gun%RF%ageing.*– New*laser*system*in*ground*laser*room.*

Following%the%RF+Gun%
reviewer’s%comments

• Increase*pulse*energy*from*ﬁber*laser*• Simplify*the*laser*system*(new*mul9@pass*ampliﬁer)*• This*comming*summer:*(Postponed%the%pulse%shaping%un<l%Phase+III%)

– Third%RF+Gun%(nomal%laser%injec<on%/%cavity%modiﬁca<on%/%cathode%change)%– Simple%Nd%ampliﬁer%for%Phase+I%&%II%stable%injec<on%#60
($/.,0($5+1'($4(31/,44,10,0*62(3
0-(&5,1060
($/.,0($5+1'(
$4(31/,44,10,0*#

10%ps%gaussian%is%enough%for%Phase+I%(1nC)%&%II%(2nC),%%postponed%the%pulse%shaping%un<l%Phase+III"  "  !

3 ($
'$4(3 "  




"
 




"
 




" 




"
 



" 3 ('$4(3!

"%$4(33 (: !
+,&$0(3 ( :

+$4(+$4(+$4( !  !
(83(&$5+1'("%$4(3*3160''/2.,),(3+(3/$.60'/2.,),(3"%$4(3391*(0,&00.18(/,55$0&(0.18(/,5(4,*0(7(.12/(05045$..$5,102(3$5,10Beam*line*will*be*upgrade*on*up*and*down.*

Yoshida et al.

Thermionic*DC*gun*will*be*installed*to*upper*beam*line.*

10*nC*
for*positron*primary

70*MeV
Acc.tubebuncher prebuncher

SHB2 SHB1

Energy*slope**Chicane
30*MeV*20*psec* Bunch*compression 20*psec*

Acc.tube

RF*gun

5*nC*
Low*emiQanceThermionic*
DC*gunSecond*Side*coupled*Quasi@travelling*wave*RF@Gun

Second*RF@Gun*under*brazing*

Present*cathode

Condi9oning*progress*was*too*slow.**
Frequent*break*down*is*the*issue*to*be*cured.**Cathode*rod*contact?**Cathode*material*ﬁxa9on?**Cathode*material*spuQering*due*to*laser?*
We*have*to*analyze*break@down*issues.*
1. Cavity*condi9oning,*used*dummy*cathode*rod*
without*cathode*material*(all*Cu).*
2. Replace*new*cathode*rod*with*material*(new*ﬁxa9on*is*shrinkage*ﬁt).**3. For*reduce*mul9pactoring*eﬀect,*another*cathode*cell*design*is*required.*

New*cathode

shrinkage*ﬁtShort*term*plan*for*laser*development• Following*recommenda9ons*at*review*mee9ngs*• Undeground*Yb@Fiber*+*Yb:YAG*(Exis9ng)*– Downgrade*to*25Hz*2@loop*ampliﬁer(Done)*=>*Fix*conﬁgura9on*– Increase*monitor*points*/*quadrant*detector*etc..*– Improve*stability.*• Underground*Yb@Fiber*+*Nd:YAG*(Yb@Fiber*small*upgrade)*– 1064nm(Nd:YAG*wavelength)*is*converted*by*exis9ng*Yb*oscillator.**– Stretcher*for*10*ps*is*similar*to*exis9ng*one.**– Exis9ng*ﬁber*ampliﬁer*(Thorlabs)*is*best*ﬁt*to*amplify*1064nm.**– Preliminary*test*using*exis9ng*Nd:YAG*DPSS*Module*(10Hz).**• Ground*Yb@Fiber(Commercial)*+*Cryogenic*Yb:YAG***=>*Postponed*the*opera9on*un9l*Phase@III.*• Ground*Yb@Fiber(Commercial)*+*Nd:YAG(Commercial)*– MENLO*Orange*oscillator*wavelength*must*be*shihed.****or*use*Nd:YLF*(1047nm).**– Yb@Fiber*commercial*ampliﬁer*can*be*used*for*1064nm.**– Nd:YAG*50Hz*DPSS*commercial*module**– Vacuum*duct*/*Room*environment*/*Virtual*cathode.*New high gain multi-pass amplifier(10-15 pass x 2 loop)
to simplify the laser Laser Diode

OUTPUTINPUT

10-15pass

1pass



Simplify*and*stabilize*our*laser*system*without*pulse*shaping
Exis<ng%laser%system

114.2 MHz
Menlo

Yb@doped*ﬁber*
oscillator*with*Transmission*gra9ng

@ 1030 nm

PCF*Yb@doped*ﬁber**
ampliﬁerPulse*picker

Yb:YAG*thin@disk*
mul9pass*ampliﬁer*(25*Hz)

@ 1064 nm

Simple%Nd%ampliﬁer%laser%system%without%pulse%shaping%according%to%RF+Gun%reviewer’s%comment
LIEKKI*Yb@
doped*ﬁber**
ampliﬁer

Op#lab''YDFA,r,40,S,'
Output%power%of'20W'

Pulse*
pickerGrating pairYb*ﬁber*
Oscillator
Spa9ally*dispersed

Commer<al%Nd:YAG*rod*
mul9pass*ampliﬁer*(10*Hz*=>%50%Hz)

Fiber*Ampliﬁer*@1030*nm
Fiber*Ampliﬁer*@1064*nm*

Strecher*for*Yb:YAG*&*Nd:YAGYb:YAG

Nd:YAG

Center*wavelength

1030*nm

1064*nm

Gain*spectrum*width

~2*nm

~0.5nmDistance*of*the*Stretcher*to*30*ps

1.5*m

6*m*(×4)

Gain*spectrum*of*Yb:YAG
Distance ofgrating pair

30*ps
2.0nm

Grating pairNd:YAG*DPSS*module*regenera9ve*ampliﬁer*(experimental)
Regenera9ve*ampliﬁer

Oscillator

Test*at*A@1*underground*using*exis9ng*Yb@Fiber*oscillator.

Thermionic Gun

Thermionic gun

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

43

Thermionic GunPreparation of Thermionic Gun! Under refurbishment"Raise by 75cm not to conflict with straight RF-gun$ As well as angled RF-gun"~ Jun.2015.

! May serve primary electron for positron generation
Thermionic gun

RF gunLinac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

48

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

50

Positron Enhancement

Positron generator

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

51

Positron Enhancement

Positron Generation!4-times more positron is required at
SuperKEKB than KEKB
"Safety measure was taken after cable fire during thetest of Flux Concentrator (FC)"New components in
100-m capture section
were tested in steps"High voltage tests intunnel in April"Beam tests with electron
in MayLinac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Positron Enhancement

Positron from New Positron Capture Section! Generated positron ~0.1nC wastransferred to the entrance ofdamping ring
! With higher magnetic and electricfield, 4-nC positron will begenerated! Target shield(40cm x 6m long)
Beam position
will be finalized
Horizontal! Alignment will be
Vertical
improved
3mm # 0.1mm
Beam charge

Linac Upgrade Progress towards SuperKEKB

Large
Flux
concentrator
aperture S-bandand structure
beforefollowingsolenoidsolenoid/quad& quad installation

400 m~0.1 nC

PositronPrimary Electron
W target
K.Furukawa, KEK, Jun.2015.

55

Positron Enhancement

鳥瞰図：南東方向から見た図． トンネル1-5 陽電子
ターゲットの60cm上流から６ｍの範囲に設置．3 月時の遮蔽鉄の厚みは200mm（図中の赤＋灰色部）．
200mm角柱 6本が現場通路上ビームラインよりに設置される．鉛カーテンを設置すると、通路の幅が現場では1400mm．申請電流値に合わせて鉄の厚さを追加する予定．
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

58

Radiation Shield

Radiation Shield Construction#15 region

Iron shield

Flux Concentrator

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

59

Positron Enhancement

T.Kamitani

Positron Generation1) Installation of positron generator for SuperKEKB in April 2014
(Beamline construction since summer 2013)(positron target, spoiler, Flux Concentrator, bridge coils, LAS structures [x6], DC solenoids [16+13],e+/e- separator, quads [>90])

2) Commissioning of positron beam, observation of the first positron afterreconstruction for SuperKEKB, further improvements expected
Primary e- [nC] Positron [nC]
June 2014
Specification(at SY2)

0.6

0.12

x17

10.0

DR injection(2017?)
3)

5.0
4.0x42

Efficiency

Parameters

20%

FC 6.4kA, Solenoids 370A,
LAS capture field 10 MV/m

50%
40%

x2.5

FC 12kA, Solenoids 650A,
LAS capture field 14 MV/m
Energy spread acceptance0.5%

Oct.~Dec.2014 : Linac commissioning
Jan.~Mar.2015 : Construction
Apr.2015~ : Linac commissioning
Feb.2016 : LER injection

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

ScheduleSchedule

Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Schedule

RF-Gun e- beamcommissioning
at A,B-sector

Linac Schedule Overview

e- commiss.
at A,B,J,C,1

e+ commiss.
at 1,2 sector (FC, DCS, Qe- 50%)e- commiss.
at 1,2,3,4,5 sector

Phase1: high emittance beam for vacuum scrub
Phase2,3: low emittance beam for collision

Time →Location↓StagedLicenses

LowEmittanceBeams

4+1 Ring
Injections

DRCommiss.
1 nC
Phase1

Without Top-up: Electron: Positron: Low current electron

Linac Upgrade Progress towards SuperKEKB

non damped e+ commiss.
at 1,2, 3,4,5 sectors
e- commiss. at A→5 sectors

2 nC
Phase24 nC
Phase3

Direct PF-AR BT
damped e+ commiss.
at 1→5 Qe+ = 1~4nC
e- commiss.
at A→5 Qe- = 1~5nC

Improved
RF gunK.Furukawa, KEK, Jun.2015.

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Schedule

Injector linac schedule! Feb.2016 – Jun.2016: Phase-1 commissioning" Normal-emittance, 1nC/bunch electron/positron beams, without damping ring (DR)$ With combination of RF-gun and thermionic gun$ ex. Electron with 1nC RF-gun, Positron with ~6nC thermionic gun% (depends on downstream configuration after DR delay affecting PF/PF-AR injections)! Jan.2017 – May.2017, Damping ring commissioning" 1nC – 2nC/bunch positron beam, to/from DR! Jun/Oct.2017 – Feb.2018, Phase-2 commissioning" Low-emittance (20mm.mrad, 0.1%), 2nC electron/positron beams, with DR$ Low-emittance electron beam with RF-gun, 2nC$ Primary beam for positron with RF-gun or thermionic gun, 5nC! Oct.2018 – …, Phase-3 commissioning" Low-emittance (20mm.mrad, 0.1%), High charge electron/positron beams, with DR$ Low-emittance electron beam with RF-gun, 4nC$ Primary beam for positron with RF-gun or thermionic gun, 10nC
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

63

Schedule

Radiation protection licenses!Staged upgrade of beam limits!Final goal is 1250/625 nA before/after target"Same as KEKB (with limited shields)!Applications"Fall.2013. 10 nA at #28 dump, 1250 nA at #A2 dump
"Spring.2014. New utility rooms, 50 nA at #61 straight dump
"Feb.2015. 200 nA at #15 target"Late 2015.(?) 800 nA at #15 target, 625 nA at #61"Sometime 2016.(?) 1250 nA at #15 target
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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SummarySummary! Steady progress towards first MR injection in 2015
! Finished earthquake disaster recovery in 2014
! Will make staged improvements up to Phase-III! Alignment: almost confident on the required precision (0.1-mmlocal, 0.3-mm global), need to maintain for longer term
! RF gun: following recommendations at review meetings withcommercial devices and Nd-based lasers! Thermionic gun: waiting to be commissioned! Positron generator: waiting for license test
! Will balance between final beam quality and staged operation! Will select optimized route depending on available resources
Linac Upgrade Progress towards SuperKEKB

K.Furukawa, KEK, Jun.2015.

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Mt. Tsukuba

Thank you
SuperKEKB
dual rings
PF-ARPF

Linac Upgrade Progress towards SuperKEKBInjector
LinacK.Furukawa, KEK, Jun.2015.

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