Injector alignment
KEKB Accelerator Review Committee
14 June, 2016
Toshi Higo (Injector linac group)Contents
1. Alignment scheme– Laser PD and tracker

2. Initial alignment– Accelerator girders and magnets

3. Floor movement– Refinement of PD measurement

4. Effort against emittance growth– Present development– Near future perspective

5. Conclusion

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Who are contributing• Accelerator group– Enomoto, Higo, Kakihara, Tanaka, …..

• Control group– Mikawa, Satoh, Seimiya, Suwada, ……

• Injector group– Yoshida,• Mitsubishi Electric.
– Mizukawa, Kimura, Kudo, Kusano, Suzuki, Toyotomi, Ushimoto, ….

• Outside company– Nishitani, Chiyokura, …

• Magnet group of KEKB ring
– Masuzawa, Sugawara, ….. but still loose coupling
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Requirement and strategy• Requirement• Strategy• Laser PD measurement• Initial alignment of girder• Hard ware alignment on girder

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J-ARC

Linac layout and alignment
requirement

Laser

120m
BACRings
12500m435 End PDσ < 0.1 mmà βγε 20 mm·mradalmost kept.
σ > 0.1 mmà emi9ance preserva<onrequired.

Requirement
Local σ < 0.1mm
Global σ < 0.3mm
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Alignment scheme
Reﬂectors forlaser tracker use

4

Reference pointof girder

Hard ware
Mechanicalreference 3

21Laser PD

2016/6/14

Girder

1. Girder set to laserreference by PD
2. Support set w.r.t. mecha.
reference
3. Hard ware aligned withmecha. reference
4. Hard ware alignment
checked by tracker

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500m straight reference line by laser•••••2016/6/14

500m laser line stabilized by laser passage tilt.
Improved data reliability with robust measurement.
Sensitivity calibration done with laser tilting
Some sensors automatically and continuously
measuring now
Started PD radiation damage evaluation

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Initial alignment of girders
1. Girders in sectors 3—5 were quickly aligned in2011 after the earthquake.
2. Positron generation section was installed bysummer 2014.
3. By late Jan. 2015, all units in 3—5 sectors werealigned straight.
4. These alignment reading is better than 0.1mm
at the timing of installation.
5. Alignment has been measured from time to time
without further re-alignment.
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Measurement 141128 -- 160330
VerticalHorizontal

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Mounting tracker reflector on eachhard ware

Mounted oncoupler OD

Reﬂectors for
old Q-magnet

Arm from PD
to reﬂector
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Hard ware alignment on each girder
measured in Jan. 2016
B4C526

Horizontal
4036

σ=0.056mm

354654

Ver<cal5055

σ=0.051mm

403025302020151010500-0.15

2016/6/14-0.1-0.05

00.05

0.1

0.15

-0.15 -0.1 -0.05

KEKB Accelerator Review (Higo)

00.05

0.1

0.15

0.2

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Accelerator position on girder unit 54
from August 2014 to May 2016

Unit 54 in nearly 2 years
from Aug. 2014 to May 2016
W[mm]

EU

Movement in 1.5 year between
July 2014 and January 2016

[mm]

[mm]

ACC’s can be aligned on eachgirder within below +/-0.1mm.
It is speculated to be stable within+/-0.05mm.
This should be confirmed orrealized.

D[mm]2016/6/14

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Floor movement• Laser PD measurement showed movement of larger
than a millimeter• Severe at expansion joints• Started continuous measurement over 500m
• Will start detailed 40m evaluation across a joint

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Floor moves by fraction of 1 mm
example in more than a year (2015/4/3~2016/6/2)
VerticalHorizontal

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Floor movement
close-up w.r.t. 2016/3/30

Expansion joint

Expansion joint~20m from expansion joint is mostly moved.
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Expansion joint and evaluation
EastwallDownNotrth
BeamWestwallUp
South

Dial gauges

Expansion joint

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Relative movement
across expansion joint at 28 unit
UpNorthTyphoonEastOFF
19 Sep. 2014•••••2016/6/14

Operation

31 Oct. 2014

Daily regular motion exists
Gradual drift over a month after operation starts
Sensitive on tunnel temperature
Big perturbation due to typhoon
Show a year cycling.
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PD measurement
automatic and continuousMeasurement in every 4 hours
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Automatic measurement in every 4 hours
at 10 locations for half a year
from January to June in 2016
Horizontal

Absolute

Vertical

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Rotation

19

Daily motion
Movement in 4 hours or those in a week
Red arrow = +/- 0.1mm band

4 hour motion
Hor.

Hor. During 2 weeks
Ver.
Ver.

1 week motion
Hor.

Daily motion full ~ 0.1mm
Motion in 4 hours ~ 1 week +/- 0.1mm

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Ver.

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Channel sum(V)A concern
PD deterioration due to radiation

SumCh1-4

TimeDeterioration observed during phase-1 operation for those at collimator.
How to use the PD information needs to be studied.
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Simulation and cures• SAD simulation started• Possible cure methods are under consideration.
• How to stabilize position to keep alignment?
– Studies should be made how to compensate the floor movement– Do we need other tool to evaluate the floor motion? i.e. HLS or WPS– How to implement beam information into feedback• Compensation algorithm– One-to-one steering à Minimize residual error^2– DF or WF steering– How fast can we and how frequent should we apply offset injection?

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SAD simulation on emittance growthalong 500m straight section
Assumption

Procedure

Sector C~5 over 500m
εinj = 10 µm
σz = 10ps / 2.35
δe = 0.4%
σQ = 0.2mm (3σ cut)
XACC, YACC =Girder(measured)• 2aACC = 20mm (diam.)for wake calc.
• Wt = Yokoya formula

1. Orbit correction at BPM
without wake field
2. Offset injection (x, x’, y,y’) at the front of sector
C with wake field ON
3. Add variation inmisalignment of ACCand Q
4. Add jitter in ST and Q
5. Check response tobeam injection jitter

••
•
•
•
•

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60 seeds of misalignments
Phase-2
2nC

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Phase-35nC

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60 seeds of misalignments+ perturbation unable to be compensatedInjection jitter

K-value jitter
ST: K ji9er = Peak K value X 0.08% (P-P)
Q: K ji\er = Peak K value X 0.32% (P-P)
Injected beam: No ji\er35With jitters
Average without jitters
Average with jitters

Normalized EMIT [mm.mrad]

Normalized EMIT [mm.mrad]

35

ST, Q: K ji\er = Operadon K value X 0.2% (P-P)
Injected beam posi<on ji9er ~ beam size:
Sigma 0.1mm Gaussian in 100 seeds

302520With jitters
Average without jitters
Average with jitters

3025

20

1515
1010
0.1

0.15
0.2
0.25
Misalignment [mm]

0.15
0.2
0.25
Misalignment [mm]0.30.3Mainly due to ST-K jitter2016/6/140.1

Mainly due to injection jitter
Jitter should be less than beam size

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Emittance growth under measured misalignment+ random movement not to be compensatedBlack: σACC=0.1mm, σQ=0.2mm
Red = X4

Red = X2Def2mult

2015101025201510101214161820
Normalized EMITX [mm.mrad]

25201510101214161820
Normalized EMITX [mm.mrad]

222225201510101214161820
Normalized EMITX [mm.mrad]

Def
8mult

504030201010152025303540
Normalized EMITX [mm.mrad]

60Def4mult

30
Normalized EMITY [mm.mrad]

Normalized EMITY [mm.mrad]

22Def
2mult

30

2015/04/03

1214161820
Normalized EMITX [mm.mrad]

Normalized EMITY [mm.mrad]

25

Normalized EMITY [mm.mrad]

2016/01/21

Def4mult

30
Normalized EMITY [mm.mrad]

Normalized EMITY [mm.mrad]

30

Red = X860

22Def8mult

50

4030

201010152025303540
Normalized EMITX [mm.mrad]

Uncompensated random movement of 0.4mm in sigma is marginal?
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2645

Floor movement to be compensatedUnit mm2016/6/14

Horizontal

Ver<calDaily

0.10.1Week

0.10.1

Year

0.51

Speed

0.01mm/hr

0.01mm/hr

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Movers under study

Mover tests foraccelerator girder

2016/6/14

Support structure being
developed for pulse magnets

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Requirements and strategy
against floor movement• In phase-2 timeframe– Alignment as is with trial cures at some points– Confirm overall and year-scale floor movement– Evaluate distance scale from joint– Try to detect movement with beam
– Investigate the cure algorithm with simulation– Study feasibility of mover or passive bridge• Development for phase-3– Alignment corrected once more and stabilized withmovers or suppression mechanism near relevant
expansion joints– Beam manipulation to keep golden orbit– Compensation such as offset injection is developed
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Concluding remarks

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Development toward Phase-3
Perspective on development and operation as of 160614
2016
8 9 10 11 12 12345

2017
6 7

SuperKEKBPF

4 5 6 7
Phase-1 1nC
3TElectron
Positron

RFG・・・・・・・・・・・・・・・・・・・・
AT(Thermionic gun at A1)
FC refurbish
・・・・・・・・・AT end

3TMagnets

8

9 10 11 12 1 2 3 4DR Phase-2 2nC
A1520186 7

8

9 10 11 12 1
Phase-3 4nC

23RFG
RFG
Pulse magnet install

Beam study

beam study on emittancebeam study ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・

Simulation

Simulation study by reflecting practical pattern, amount and speed of floor movement

Floor meas.

PD measurement over shole linac as frequent as possible
10 more PD's Evaluation of floor movement near expansion joint
Manufacture laser PD or other tool for FB if needed
Install the above PD if madeMover study
Large-scale bridge

Mover test (ACC girder, pulse-mag support)
Design study of passive structure feasibility
Strategy decision

2016/6/14

Produce a few sets of final girders
Install the above girders
Evaluate with beam

KEKB Accelerator Review (Higo)

Mass production as needed
Install final version
Tune up emittance control

31

Concluding remark
1. Initial girder alignment in 2014
Done with residual ~0.3mm in sigma over 500m line.

2. Hard wares alignment on girder improved
Done with errors 0.05mm in sigma
Kept for in a year scale

3. Floor continuous measurement
Movement mostly near expansion joints
Daily motion ~0.1mm to yearly ~1mm

4. Floor sophisticated evaluation
Will explore near expansion joint
Will design compensation mechanism

5. Compensation mechanism
Basic study of movers is under way
Passive structure design study to be made2016/6/14

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Concluding remark (cont.)
6. Tools to identify the movement
Radiation resistive PD is being searched
Pending now to develop other evaluation tools
Should study how to use which beam information

7. Beam study
Should study beam emittance on floor movement
Study offset injection

9. Test girderInstallation in mid 2017
Should study effectiveness during phase-2

10. Full scale cures
Installation by Phase-3
Sophistication in parallel to phase-3 operation
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