500m級超高精度レーザー直尺を用いた�
微小地面変動の連続観測技術の開発

T. Suwada, Y. Enomoto, K. Kakihara, K. Mikawa, T. Higo,
Accelerator Laboratory, KEK, Tsukuba, Japan�

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 20171

Introduction�
▲▲▲

超高精度レーザーアライメントシステムを利用して入射器トンネル床面の微小変動の連続観測を平成28年1月7日から開始. �±0.08µradの範囲内に安定化された500m級の超高精度レーザー直尺とトンネ
ル床面に分散配置した光センサーの自動計測技術を独自に開発.
約半年に及ぶ観測データによると••▲床面は決して不動ではなく、日々の動きは複雑で不規則ながらも全体的には一日当り約5µmの大きさでほぼ一様に変位していることを観測.
一日当りの変位の大きさは髪毛1本の太さと比べても極めて微小で500m級超高精度レーザー
直尺による計測で実現.�

スーパーBファクトリー計画(SKEKB)における入射器の性能向上に貢献するのみ
ならず、次世代の長距離線形加速器における高精度アライメントへの応用や高度なビーム制御技術に大きく貢献すると期待.

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

2

Alignment measurement scheme for girders andcomponents �
z=0m

Laser
He-Ne�

z = 500 m

Long-range laser-based alignment system�

Initial QPD ( for reference )�
#1#2

Vacuum window( for reference )� Last QPD

#3

QPD

#48

............

Acc. unit

Vacuum window• Long-range alignment system for girders (accuracy�σ ~ 100μm)�
The girder units can be aligned with a laser-based alignment system.�
• Short-range alignment system for components (accuracy�σ ~ 50μm)�
The accelerator components on a girder unit are aligned with astandard laser-tracker technique.�

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 20173

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 20174

Girder unit structure �(a)Girder plate

9600

Girder plate
Guide rails

Guide rails

Accelerating structures(b)

Girder plate

Accelerating structures

Beam
Laser
Accelerator girder

Quadrant silicon Photo-Diode:QPD�(c)A

Target for laser tracker�

780

1200

B

A: Beam height
B: Laser height

T. Suwada, et al.,Rev. Sci. Instrum 81, 123301 (2010).�
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

5

KEKB linac layout and the laser-based alignment system�•Two long straight sections, AB (125m) and C5 (475m) sections with independent
laser sources (He-Ne) and quadrant silicon photodiodes (QPDs).
Two (seven) remote-controllable QPDs were installed in the summer shutdown of2014 (2015) at multiple locations just near expansion joints (e.j.) of the linac
building (see Table 1).

•

AB laser fiducial line (132 m)

e- E = 1.5 GeV�
B-8

Laser

C-2

o

180 -Arce- 1.5 GeV
3-2

3-3

3-4

3-5

3-6

Sector

3

B

B-5

B-3

B-6

B-7

C-1

Sector
e. j.

C-3

C-4

e. j.
Sector

3-8

C-5

B-2

C-6

B-1

C-7

A-4

A-3

C-8

1-1

C

A
e. j.

A-2

1-2

e. j.

AT Gun (e-)

to DR

Laser

A-1

1-5

1-3

e+ Target

1-6

RTL
1-7

Sector

1-8

e. j.

1

2-1

2-2

2-3

2-4

Sector

2-7

2-6

2-8

2

4-1

4-2

4-3

4-4

4-5

4-6

4-7

4-8

e. j.

5-1

5-2

5-3

5-4

Sector

Sector 4
C5 laser fiducial line (500 m)

5-5

5-6

5

e. j.

5-7

e. j.
SY2

5-8

e. j.

SY3

SKEKB LER/HER
PF-AR

e- E = 7 GeV, e+ E = 4 GeV�

M. Akemoto, et al., Prog. Theor. Exp. Phys. 2013 , 03A002.
Tsuyoshi Suwada /KEKB Injector Linac

LTR

PF

Primary e- for e+ production E = 3.3 GeV

e. j.
3-7

B-4

Sector

KEK加速器セミナー, 29 Mar., 20176

Table of new remote-controllable QPDs
1. Summary table in the locations of theremote controllable QPDs, andexpansion joints (e.j.) along theinjector linac from the laser source.
2. Some measurement results, themaximum norm (rm) of thedisplacement vector and the maximum
slope (sr) in the variations in the time
traces of the norm, are also
summarized depending on the QPD
locations.

�reference QPDs

7

(fixed reference QPD)�
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

Injection Optical System�
Optical system••

10-mW He-Ne laser
Solid and large optical table

Vacuum system••

Two scroll pumps (1000l/min)
Vacuum level ~3 [Pa]Parallel plate for translation tuning�f5000 lens for injection angle tuning�
Optical table (1500×900×112tmm3)�
Girder (Fe)�
Iron plate (1510×500×20tmm3)�
Isolated floor separated from the tunnel
floor by a 100-mm gap (1510×500mm2)�
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 20178

Laser optical system – simple dioptric systemusing dioptric lenses and reflecting mirrors –�Wide beam for Fresnel lens method�PBS f150
BD

f50

He-Ne Laser
10mW (or 1mW)�

f300

Translation along x and y axes�

f300

y� f5000

Parallel plate
Rotation around x and y axes�

x�

PBS

For injection angle tuning�
Narrow beam for QPD method�f1500
Red : Narrow beam, Blue : Wide beamTsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017y�x�For translation tuning �21500 × 900 mm
9

Laser profiles at the initial and last QPDs�

@ Exit of the optical system (z=0)
Wx ≈ Wy ≈ 29mm (4σ width)�
Tsuyoshi Suwada /KEKB Injector Linac@ Last QPD (z=500m)
Wx ≈ 21.2mm(4σ width)Wy ≈ 17.8mm�

KEK加速器セミナー, 29 Mar., 201710

Sensitivity measurements of the laser axis
at z = 500m�

Horizontal�

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

Vertical�11

Feedback control for stabilizing an injection laser
axis�
y

z

x
Laser

z=0m

z = 500 m

Initial QPD

Last QPDFB control for the injection angle of theStage controller laser axis at the optical system
Position stability Δx ≈ Δy ≈ 30 μm (1σ)�
PC

CCD

Detector
Oscilloscope
PLC/ADC�

Feedback for the motion control of linear stages through LAN

Stage with pico-motors for f5000 lens (Crucial for stable laser axis)�
••Tsuyoshi Suwada /KEKB Injector Linac

M-562-XYZ/Newport, �translational resolution 30nm/step à ~1nrad/step
The drive shaft is rotated by frictional force of piezoelectric element and thestage translates in the transverse plane. �
KEK加速器セミナー, 29 Mar., 201712

Position stability of the laser axes at the last QPD(z=500m)�
(a)

(b)

600

<∆ x> = -1 µm
σ = 33 µm

Horizontal
500<∆ y> = 0.5 µm
σ = 41 µm

Vertical

x

y

400

Horizontal�

400

500

Vertical�

300

300
200

200

100

100

0

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0

-0.2

-0.15

-0.1

-0.05

∆ x [mm]Tsuyoshi Suwada /KEKB Injector Linac

0

0.05

0.1

0.15

∆ y [mm]

KEK加速器セミナー, 29 Mar., 2017

13

0.2

Calibration procedure for the QPD
displacement to the laser axis �44x0 = -3 mm
x0 = -2 mm
x0 = -1 mm
x0 = +1 mm
x0 = +2 mm
x0 = +3 mm

3
2

2
1

y [mm]

x [mm]

1
0

0

-1

-1

-2

-2

-3

-3

Horizontal Calibration-4

Vertical Calibration

-4
0

100

200

300

QPD Location [m]•y0 = -3 mm
y0 = -2 mm
y0 = -1 mm
y0 = +1 mm
y0 = +2 mm
y0 = +3 mm

3

400

500

0

100

200

300

400

500

QPD Location [m]Results in the horizontal calibration procedure for all the remote-controllable
QPDs. It should be noted that a laser source and the fiducial QPDs are located at z
= 0 and z = 500 m, respectively. The target positions controlled with the feedback
control are defined by x0 and y0 at z = 500 m.�
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201714

Remote-Controllable Quadrant Silicon Photodiode(QPD)
Vacuum Chamber

D=117mm�
QPD

Air Cylinder•••Signal Extraction

Valve Control
Solenoid Valve

A remote-controllable QPD sensor, QPD: OSI Optoelectronics, SPOT-9D(D =10mmϕ)�
Aperture D = 117 mm (effect. aperture D = 92 mm)
Actuator-based QPD driving system with a compact air cylinder and a microsolenoid valve driven by a compressed air�15
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

Detector circuit in the local control system�
Monitor Outputs
QPD #1

2
3

Vm1
Vm2
Vm3

Detector Circuit
1
44ch ゲインバランス< +/-0.02%�

Vm4
I1
I2

y

I3
x

QPD #2

I4

Current Integrator
Current Integrator
Current Integrator
Current Integrator
Relay switch

V1
V2

A
D
C

V3
V4
I/O 1

Relay switch

QPD #10Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201716

Block diagram of a local control system�
Linac control network
Monitor Control Station
Network Switch
Linux CPU
I/O 1
I/O 2
ADC

Detector Circuit
Consoleterminal
Klystron gallery

VME/OS9Linac tunnel
Actuator
Air cylinder

Laser

スクリーンモニターシス
テムと制御は共通�

Driving shaft

Local controller
AC power
Micro switches

QPD
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201717

Expected error sources and estimations�
Errors�
Systematic error�

Statistical error�
Tsuyoshi Suwada /KEKB Injector Linac

Source of errors�

rms error (μm)�

Mechanical• Mounting error of QPD• Mounting error of QPD holder• Reproducibility of QPD position
Electrical• Detection (offset) error of QPD
Laser Shape• Profile error

10
30
30
12
10

Summation (rms sum)46

Laser stability• Laser axis stability± 30

KEK加速器セミナー, 29 Mar., 201718

Laser window�Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

19�

Time trace of a typical displacement vector @QPD-38DA �y�
7 Jan 2016�

about a half year period�

Laser�

20 July 2016�

d(r, θ)�

x�
QPD�

displacement vector d�differential displacement vector�

•Every four hours on the hour, the basic functions provided by the server start towork in order to take a series of the displacement data for all the remote QPDs.
• The results show typical variations in a time trace of the displacement vector witha feedback control on.
• It can be seen that the displacement vector has complicatedly rotated around thelaser axis along with the growth of the vector norm in the time direction.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201720

Typical displacement vectors @ QPD-38DA �
7 Jan 2016�

7 Jan 2016�

about a half year period�
20 July 2016�displacement vector�

20 July 2016�

differential displacement vector�

•Every four hours on the hour, the basic functions provided by the server start towork in order to take a series of the displacement data for all the QPDs.
• The results show typical variations in a time trace of the displacement vector
obtained for the accelerator units with the feedback control on.
• It can be seen that the displacement vector has complicatedly rotated around thelaser axis along with the growth of the vector norm in the time direction.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201721

Introduction of the Displacement vectors �
Displacement vector�

QPD_58DA�

Differential�

QPD_58DA�

• Variations in a time trace of the displacement vector obtained for the
QPD_58DA which is a feed-backed reference.

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201722

Time traces of all the displacement vectors�
norm�

phase�

•

•
•
•
•
•
•
Tsuyoshi Suwada /KEKB Injector Linac

Norm and phase of thedisplacement vectors for all
the accelerator units withfeedback control on.
The phase is defined by anangular range of 0-2π.
Data taking period: 7 Jan –20 July 2016.
Max. norm:
rmax = 0.19 - 0.88 mm
Average max. norm:<rmax> = 0.65 mm
Max. growth rate:
sr = 3.3 – 6.6 μm/day
Average max. growth rate:<sr> = 4.9 μm/day

KEK加速器セミナー, 29 Mar., 201723

Real-time measurements on dynamic floor motion �• Variations of (a) the maximum norm and (b) the maximum growth rate in
the displacement vector measurements as a function of the QPD location.�

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201724

Cross-correlation analysis between the displacement
vectors�!
!
1µ (i) = ∑ d (i),
(1)
N
N

n

n=1

!
!
!
1 N !
"
C k (i, j) = ∑ (dn (i) − µ (i) ) i (dn−k ( j) − µ ( j) ), (2)N n=1" k (i, j)
C"R k (i, j) =. (3)" 0 (i,i)C" 0 ( j, j)
C(1) <μ(i)> : average of the n-th displacement vectors dn(i) of the i-th QPD intime series with a maximum data length of N.
(2) Ck(i,j) : cross-covariance function between the n-th displacement vectors(dn(i) and dn(j)) obtained for the i-th and j-th QPDs, respectively, in timeseries with time lag of k.
(3) Rk(i,j) : cross-correlation function. Rk(i,j)=1 (-1) : strong positive (negative)correlation, Rk(i,j)=0: no correlation, k =0 (k≠ 0) stands for the cross-correlation
function at present (past) time.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201725

Spatial cross-correlation analysis between thedisplacement vectors�

•Time traces in the spatial cross-correlation function of the displacement vectors
between the reference QPD (QPD_REF28DA) and other QPDs for the accelerator
units with the feedback control on during the same term.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201726

Temporal cross-correlation analysis between thedisplacement vectors�
QPD_REF28DA�

•Time traces in the temporal cross-correlation function of the displacement vectors
between the reference QPD (QPD_REF28DA) and other QPDs for the accelerator
units with the feedback control on during the same term.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201727

Cross-correlation analysis between the displacement
vectors�

•Time traces in the spatial cross-correlation function of the displacement vectors
between the reference QPD (QPD_REF28DA) and other QPDs for the accelerator
units with the feedback control on during the same term.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201728

Animations in time series for the cross-correlation
analysis between the displacement vectors�

3D Cross-correlation plot�Real-time measurement intime series of the crosscorrelation function�
Tsuyoshi Suwada /KEKB Injector Linac

3D Displacement vectors�
Real-time measurement in time seriesof the displacement vector�
KEK加速器セミナー, 29 Mar., 201729

Summary�• 今後は、さらにデータを蓄積し入射器トンネルの長期変動傾向を捉
えたい.
• 地面変動のブラウン運動成分（拡散成分）の定量化を行う.
• 産業応用：ダム事業、トンネル構築、堤防建設など高精度な長直尺を必要とする大規模土木事業など産業応用のみならず、地震や地殻変動を監視するための大規模観測網にも応用可能.

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201730

Back-up files�

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201731

Results of the laser size measurements along the linac�•Direct beam size meas.
Δ: with CCDs at two end points• Indirect beam size meas.
: by a mapping with a
movable QPD in the x and y
directions at the middle locations,while the laser axis is fixed•
Fitting function�

Tsuyoshi Suwada /KEKB Injector Linac

Based on a least-square fitting procedure withstandard Gaussian laser optics, the widths
propagating along the z-axis were obtained asfollow:
Rayleigh lengths zRx ~ 308 m, zRy ~ 321 m,
Waist locations zx0 ~ 358 m, zy0 ~ 399 m,
Beam sizes at waist locations Wx0 ~ 18.8 mm, Wy0~ 18.0 m,�
KEK加速器セミナー, 29 Mar., 201732

Short range component alignment on the girder�Reflectors
for laser
tracker�Accelerator
structure�

2�
Mechanicalreference�

Referencepoint
extended fromlaser PD�

Girder�1�

3� Align andcheck withlaser tracker�

Laser QPD
reference �Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

33�

Laser system under operation

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

34

Remote-controllable QPDs installed at SY2�Beam axis
1200mm high�e- beam

Laser
QPD_28REFUA
QPD_28G6DA

Laser axis
780mm high�
Expansion Joint

35
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

10-mW He-Ne Laser delivering
W~30mm (FW)at the injection point�

W~30mm (FW)at the 500m-long linac
end point�Vacuum level ~5Pa in laser pipes
with two scroll pumps (1000l/min)�
Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

36

Quadrant Silicon Photo-Diode (QPD)
stopper�

QPD sensor�

QPD sub-holder�

QPD: OSI Optoelectronics
SPOT-9D (D=10mmϕ)�
••130mmϕ�signal pick-up�QPD holder�•

QPD is mounted in thecenter of a sub-holder.
The sub-holder can standupright by rotation of a leverthrough hinge structure. The
inner diameter of the holder
is 130mmΦ.
The QPD holder isconnected to a laser pipe
(SUS) by flange-flange
joining.�

QPD target�
37
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 2017

Time traces of the displacement vectors (cont’d)�
•It can be understood that the norms of the displacement vectors monotonicallyincrease (except for that of QPD REF1UA), while it can be seen that there are someincomprehensible fine structures in each time trace.
• The variations in the maximum norm (rm) of the displacement vector in each time
trace as a function of the QPD location are spread over a range of 0.19-0.88 mm
during a half year period, and the average maximum norm (⟨rm⟩) is 0.65 mm.
• The variations in the maximum growth rates (sr) in the time traces as a function of
the QPD location are spread over a range of 3.3-6.6 μm/day depending on the QPD
location, and the average maximum growth rate (⟨sr⟩) is 4.9 μm/day.
• It can be clearly seen that relatively large stepwise jump arises on 28 January 2016
in the time traces of the phase for QPD_1814DA and QPD_28REFUA. It takes
about four days in the rise time of the jump, and on the other hand, in the variationsin the norms of the displacement vector during the corresponding term are less than
0.2 mm. It could be understood that during the corresponding term the displacement
vector of the accelerator unit has rotated rather than increased in the transverse
plane.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201738

Cross-correlation analysis between the displacement
vectors (cont’d)�
• Each cross-correlation function varies irregularly in the corresponding time
trace, and however, the averages in the time traces decrease in the range of
R0 = 0.67 to 0.48 in accordance with the distance from the reference QPD(except for QPD REF1UA where R0 = 0.06).
• Relatively strong positive cross-correlations show high coherency on
average in dynamic displacements of the tunnel floor in the time series
along the entire length of the linac tunnel (except for QPD REF1UA).
• It should be noted that the time trace in the cross-correlation function for
QPD_REF1UA is markedly different from those in the other crosscorrelation functions. It seems for QPD_REF1UA to stand alone from theother building blocks.

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201739

Cross-correlation analysis between the displacement
vectors (cont’d)�
•
•
•

•

•

The 500-m-long linac building has two floors, which together constitute the
klystron gallery and the in-ground tunnel.
The linac building comprises eight building blocks that are joined to be linearlyaligned with seven expansion joints, which can absorb a certain amount of elastic
deformation caused by expansion or contraction of the building blocks.
However, residual amounts of elastic deformation may induce deformation of thebuilding blocks themselves. This may increase the displacement of the accelerator
units through displacements of the tunnel floor, triggered by the complex processes
that were mentioned previously.
In particular, it should be noted that the fiducial points created by the laser axis canmove dynamically and independently in proportion to the displacement vector of
the tunnel floor, even though the last fiducial point is strictly fixed at the last QPD
center with the feedback control on.
Thus, the laser axis itself cannot become an entirely fixed and stable fiducial axis
as an absolute fiducial line, because it is not possible to directly stabilize dynamic
ground motion.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201740

Data-taking procedure on the real-time measurement�• Every four hours on the hour, the basic functions provided by the server
start to work in order to take a series of the displacement data for all the
QPDs.
• The basic functions comprise• a) feedback control for the laser axis, the end positions of the laser
axis at the last QPD are stabilized by the feedback control until thetransverse positions of the laser axis are within the allowable region of±50 μm from the center of the last QPD.
• b) actuator control for the QPD, the first upstream QPD is driven to
the central position of the laser pipe.
• c) data taking for the QPD, displacement data of the QPD arerepeatedly taken one thousand times, then average and standard
deviation are calculated by using the four output voltages alongwith the x and y displacements.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201741

Super
KEKB
Acceleratorcollider
The Super
KEKB: an electron-positronwith components
asymmetricenergies�
Upgradedfor SuperKEKB
Complex
Upgrade of SuperBelle New QCS(Final focus system)
Crossing angle
22 mrad (KEKB)
30 mrad (SuperKEKB)

7 GeV positron beam
Ib =3.6A�
3.6 A

Ante-chambers,
comb-type bellows, HOM absorbers

e+ E = 4 GeV�e- E = 7 GeV�
4.0 GeV electron beam
Ib =2.6A
�

Target Luminosity@SuperKEKB
L = 8 × 1035 cm-2s-1
40 times higher than the previous KEKB
L = 2 × 1034 cm-2s-1#1�
New RF Gun+ Cathode materials: CsTe, Lab6, Cu

Tsuyoshi Suwada /KEKB Injector Linac
Tsuyoshi Suwada /KEKB Injector Linac

2.6 A

500-m-long beam line for the laserbased alignment�Damping ring for e+
New e+ source

#2�

#3�

Flux concentrator (Superconducting coil)+ L-band capture section

600-m-long injector linac�
KEK加速器セミナー, 29 Mar., 201742

Position displacement distributions of the laser axes for
500-m-long straight line�
(a)

(b)

600

<∆ x> = -1 µm
σ = 33 µm

Horizontal
500<∆ y> = 0.5 µm
σ = 41 µm

Vertical

x

y

400

Horizontal�

400

500

Vertical�

300

300
200

200

100

100

0

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0

-0.2

-0.15

-0.1

∆ x [mm]Tsuyoshi Suwada /KEKB Injector Linac

-0.05

0

0.05

0.1

0.15

∆ y [mm]

KEK加速器セミナー, 29 Mar., 2017

43

0.2

QPD Tests on radiation hardness�Present QPD,
OSI (SPOT-9D)
Hamamatsu~6 times rad.
hard�Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201744

Cross-correlation analysis between the displacement
vectors�!
!
1µ (i) = ∑ d (i),
(1)
N
N

n

n=1

!
!
!
1 N !
"
C k (i, j) = ∑ (dn (i) − µ (i) ) i (dn−k ( j) − µ ( j) ), (2)N n=1" k (i, j)
C"R k (i, j) =. (3)" 0 (i,i)C" 0 ( j, j)
C(1) <μ(i)> : average of the n-th displacement vectors dn(i) of the i-th QPD intime series with a maximum data length of N.
(2) Ck(i,j) : cross-covariance function between the n-th displacement vectors(dn(i) and dn(j)) obtained for the i-th and j-th QPDs, respectively, in timeseries with time lag of k.
(3) Rk(i,j) : cross-correlation function. Rk(i,j)=1 (-1) : strong positive (negative)correlation, Rk(i,j)=0: no correlation, k =0 (k≠ 0) stands for the cross-correlation
function at present (past) time.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201745

QPD Location [m]QPD Location [m](a)Cross-correlation analysis between thedisplacement vectors(cont’d)�
(b)

QPD Location [m]•QPD Location [m]Intensity distributions in the cross-correlation function between all the QPDs in thedisplacement vector measurements of the accelerator units along the C5 straightsection obtained on (a) 15 February 2016 at 0:00 am and (b) 27 February 2016 at
8:00 am. The intensity distribution pattern in the cross-correlation function islinearly encoded by the color scale.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201746

Laser size measurements along the linac�• The beam widths were directly measured at the two fiducial
points (z=0 and z=500m).
• At other locations, they were analyzed by taking mapping dataobtained with the help of mechanically movable QPDs while
the laser beam was fixed. The mapping data were obtained bymeasuring the variations in the signal levels obtained from the
QPD depending on the transverse displacements with respect
to the fiducial line.
• The beam widths were analyzed by a least-square fitting
procedure with a two-dimensional Gaussian function for theobtained mapping data.�

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201747

Reference target for component alignment on the girder�

QPD�
Target pedestal�

Laser�
Target pedestal�

Tsuyoshi Suwada /KEKB Injector Linac�• Special jig (mechanical arm) for
fiducialization of a tracker target.
• The jig and QPD are accurately
connected by flange-flangemechanical jointing.�
KEK加速器セミナー, 29 Mar., 2017�

48�

Component alignment on the girder�
QPD�

Laser�

Tracker target�
Special jig for fiducialization of
tracker target�Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

49�

Isolated floor structure at the optical ystem�

450 mmΦ�

5000 mm�

1750 mm�

Tunnel floor�

Isolated floor (Area:
500x1500x1750t mm2) witha gap of 100 mm�

PHC: Prestressed High-strength Concrete pile�
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201750

Mechanical jig for fiducialization of tracker target�

target�Al A2024�

Tsuyoshi Suwada /KEKB Injector Linac

400mm�

SUS304 flange�

Center of laser axis�

KEK加速器セミナー, 29 Mar., 201751

Laser pipe with a viewing port�Laser�

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

52�

Support of accelerating structures�Laser�

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

53�

Connection between accelerating structure and Quad�

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

54�

3D mechanical precision measurement
in QPD holder �

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

55�

Test bench in QPD setting calibration�

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

56�

Reinforced girder�

Center support added�Leg reinforced�
Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

57�

Ultrafine stage to stabilize the laser pointing
30nm/stepe- beam�

PD�

Laser
pipe�

Accelerator
Girder�
NewPort, Co. (M-562-XYZ )Ultra fine pico-motor stage

Tsuyoshi Suwada /KEKB Injector Linac�

KEK加速器セミナー, 29 Mar., 2017�

58

Developments for the laser-based alignment system�Our laser-based alignment system was first implemented at theconstruction stage in 1982; however, the high stabilization of the laserbased fiducial line has not been realized until now.
▲ At long last, a laser line with high stabilization has been implemented
as a 500-m-long fiducial line for alignments in March 2013.
▲ We experimentally investigated the propagation and stability
characteristics of the laser line passing through metallic pipes invacuum.
▲ Pointing stability at the last fiducial point with the transverse
displacements of ±40 μm level in one standard deviation by applying a
feedback control was successfully obtained. This pointing stability
corresponds to an angle of ±0.08 μrad. This system is now fully
exhibiting the successful results for the high-precision alignment of theinjector linac currently in progress.
▲

Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201759

Stability measurements of the laser axes at z=500 m�

Time traces of the horizontal and vertical
position displacements of the laser beam at
the last QPD (a) with the feedback control
on and off during 13.5 h�
Tsuyoshi Suwada /KEKB Injector Linac

Time traces of the horizontal and vertical
position displacements of the laser beam at
the last QPD (b) with the feedback control
on during 8 h.�

KEK加速器セミナー, 29 Mar., 201760

Position displacement distribution of the laser axesfor 132-m-long straight line�Horizontal�

Tsuyoshi Suwada /KEKB Injector Linac

Vertical�

KEK加速器セミナー, 29 Mar., 201761

Girder unit for accelerating structures
4 x S-band structures�Quad�

e- beam�
QPD�

1200mm high�Laser axis�
780mm high�
QPD�

Laser pipe�Girder unit
8.44-m-long�PD�

基本ユニット�Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201762

Introduction of the Displacement vectors �

QPD_11DA�QPD_11DA�

• Variations in a time trace of the displacement vector obtained for theaccelerator units with the feedback control on.
• It can be seen that the displacement vector has complicatedly rotatedaround the laser axis along with the growth of the vector norm in the time
direction.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201763

Typical displacement vectors @ QPD-38DA �
7 Jan 2016�

7 Jan 2016�

about a half year period�
20 July 2016�displacement vector�

20 July 2016�

differential displacement vector�

•Every four hours on the hour, the basic functions provided by the server start towork in order to take a series of the displacement data for all the QPDs.
• The results show typical variations in a time trace of the displacement vector
obtained for the accelerator units with the feedback control on.
• It can be seen that the displacement vector has complicatedly rotated around thelaser axis along with the growth of the vector norm in the time direction.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201764

Introduction of the Displacement vectors(cont’d) �

QPD_48DA�

QPD_48DA�

• Variations in a time trace of the differential displacement vector obtained
for the accelerator units with the feedback control on.
• It can be seen that the displacement vector has complicatedly rotatedaround the laser axis along with the growth of the vector norm in the time
direction.
Tsuyoshi Suwada /KEKB Injector Linac

KEK加速器セミナー, 29 Mar., 201765