Institute for Cosmic Ray Research (ICRR) the University of Tokyo
KAGRA face to face meeting
University of Toyama, Toyama, Japan
1 August 2013
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Contribution
R. Takahashi, K. Ono, T. Sekiguchi, Y. Sakakibara, C. Tokoku,
M. Kamiizumi, U. Iwasaki, E. Hirose, A. Khalaidovski, T. Uchiyama,
S. Miyoki, M. Ohashi, K. Kuroda, T. Akutsu A , H. Ishizaki A ,
F. E. Peña Arellano A , T. Suzuki B , N. Kimura B , S. Koike B , T. Kume B ,
K. Tsubono C , Y. Aso C , T. Ushiba C , K. Shibata C , D. Chen D , N. Ohmae E ,
K. Somiya F , R. DeSalvo G , E. Majorana H , L. Naticchioni H , W. Johnson I ,
A. Cumming J , R. Douglas J , K. Haughian J , I. Martin J , P. Murray J , S. Rowan J ,
G. Hofmann K , C. Schwarz K , D. Heinert K , R. Nawrodt K , S. Goto L , M. Tanaka L ,
S. Ioka M , K. Nakamoto M , H. Nezuka M , KAGRA collaboration
ICRR.UT, NAOJ A , KEK B , Phys.S.UT
C , Astro.S.UT
D , E.UT
E ,S.TIT
F ,
Sannio Univ.
G , INFN H , Louisiana State Univ.
I , University of Glasgow J ,
Friedrich-Schiller-Universitaet Jena K , Jecc Torisha L ,
Toshiba Keihin Product Operations M , KAGRA collaboration
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0. Abstract
3

Contents
1. Introduction
2. KAGRA cryostat
3. Cryoduct
4. 1/4 cryostat
5. Sapphire suspension
6. Human resources
7. Summary
4

1. Introduction
Schematic view of KAGRA interferometer
Four mirrors of arm cavity will be cooled .
Mozumi
Y-end Sakonishi
X-end
Kamioka mine
(Underground site) Atotsu
Center
Vibration isolation system, Cryocooler unit, Cryostat,
Cryogenic payload

1. Introduction
Outline of vibration isolation and cryostat
14 m
Vibration
Isolation
Cryostat Cryogenic mirror

1. Introduction
Outline of cryostat to SAS
Cryogenic payload
Cryostat
Stainless steel t20mm
Diameter 2.6m
Height ~3.6m
M ~ 10 ton
Mirror
Cryo-coolers
Pulse tube, 60Hz
0.9 W at 4K (2nd)
36 W at 50K (1st)
S. Koike
4 Low vibration cryocooler unit
Remote valve unit
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Outline of vibration isolation and cryostat Vacuum chamber
Inner shield
(300K)
(8K)
Outer shield
(80K)
Pulse tube cryocoolers
2 Pulse tube cryocoolers
Baffles Cryoduct
2 Pulse tube cryocoolers

Outline of vibration isolation and cryostat
Heat link (pure Al)
Pulse tube cryocoolers
Heat link (pure Al)
Pulse tube cryocoolers
Sapphire fiber
Sapphire mirror (About 20K)
Pulse tube cryocoolers

1. Introduction
Main topics
Experiment using KAGRA cryostat
Toshiba assembled four cryostats.
Cryoduct
Redution of 300K radiation propagation
1/4 cryostat
Performance test of cryogenic payload
Sapphire monolithic suspension
Key component of KAGRA
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2. KAGRA cryostat
KAGRA cryostats have already been assembled ! at Toshiba Keihin Product Operations
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2. KAGRA cryostat
Cooling test for all four KAGRA cryostats
January 2013 – April 2013
Three of them were move to a warehouse near
Kamioka on the 27 th and 28 th of July.
Cooling test for the 3rd cryostat
July 2013 – August 2013
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2. KAGRA cryostat
Three cryostats were move to a warehouse near
Kamioka on the 27 th and 28 th of July.
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2. KAGRA cryostat
Three of cryostats were move to a warehouse near
Kamioka on the 27 th and 28 th of July.
14

2. KAGRA cryostat
Three of cryostats were move to a warehouse near
Kamioka on the 27 th and 28 th of July.
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2. KAGRA cryostat
Cooling test of KAGRA cryostat in Toshiba
Test 1 : Initial cooling time of ratidation shield
How long does it take to cool shield ?
Test 2 : Heat load test
How much is temperature with extra heat load ?
C. Tokoku et al., Proceedings of CEC/ICMC 2013 (2EPoE1-03)
K. Yamamoto et al., Opening a new era for the astrophysics:
The future detectors of gravitational waves (19 April 2013) http://gwdoc.icrr.u-tokyo.ac.jp/cgibin/DocDB/ShowDocument?docid=1615

2. KAGRA cryostat
Cooling test of KAGRA cryostat in Toshiba
Test 1 : Initial cooling time
The result (2 weeks) is similar to our expectation .
There is no large unexpected heat invasion and resistance.

2. KAGRA cryostat
Experiments in cooling test of KAGRA cryostat
Experiment 1 : Initial cooling time of cryogenic payload
This initial cooling time should be short .
Yusuke Sakakibara will explain details later.
Experiment 2 : Measurement of shield vibration
This vibration causes motion of mirrors and scattered light noise .
Dan Chen will explain details later.
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3. Cryoduct
Two items for cryoduct
(1) 300K radiation though this cryo duct must be small .
(2) Scattered light noise by this duct should be small .
Not only scattered light itself but also vibration of cryo duct should be small.
Preparation for experiment is in progress .
Yusuke Sakakibara will explain details later.
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4. 1/4 cryostat
Cryogenic payload is not a simple system.
We need cryostat to test cryogenic payload performance.
KAGRA cryostat is not appropriate for test.
(1) Difficult access in mine
(2) Cleanness must be kept
1/4 cryostat will be prepared in Kashiwa campus .
1/4 means number of cryocooler, not size.
It will be delivered on the end of September .
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4. 1/4 cryostat
Construction is in progress (Jecc Torisha).
Vacuum chamber : 1.2 m in diameter, 1.6 m in height

Construction is in progress (Jecc Torisha).
Radiation shield

Construction is in progress (Jecc Torisha).
Support frame inside radiation shield

5. Sapphire suspension
Sapphire monolithic suspension
Sapphire mirror suspended by sapphire fibers.
Key component of KAGRA
We need
(a) Drilled sapphire mirror
(b)Sapphire fibers with nail heads
(c) Bonding between bulk and fibers

5. Sapphire suspension
Drilled sapphire bulk
We ordered Shinkosha ( test sample ).
It will be delivered on the 16 th of August.
KAGRA mirrors : 220 mm in diameter

5. Sapphire suspension
Drilled sapphire bulk
We ordered Shinkosha ( test sample ).
It will be delivered on the 16 th of August.

5. Sapphire suspension
Sapphire fibers with nail heads are necessary to suspend mirrors.
Test sample (T. Uchiyama)

5. Sapphire suspension
Sapphire fibers with nail heads
MolTech GmbH (Germany) and IMPEX HighTech
GmbH (Germany) have already delivered !
Although the size is similar to that of
KAGRA , quality check is necessary .

5. Sapphire suspension
Sapphire fibers with nail heads
Quality check under collaboration with ET ( ELiTES )
Q-value
Measurement in Glasgow , Jena , and Tokyo
Plan for measurement in Rome
Thermal conductivity
Measurement in Jena, Rome and Tokyo
Strength
Measurement preparation in Glasgow
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5. Sapphire suspension
Sapphire fibers with nail heads
Latest summary
Moltech IMPEX KAGRA requirement
Q-value 10 7 at 20K
Thermal
2*10 6 5*10
Conductivity 3000 5000 5000 at 20K [W/m/K] -10000
6
Although these results are promising , further investigation is necessary.
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5. Sapphire suspension
Bonding between sapphire fibers and sapphire mirror
Investigation of
Hydroxide Catalysis Bonding is in progress in Glasgow.
(Rebecca Douglas, GWADW2013).
Strength (about 60 MPa) measured by her is 10 times larger than those of previous papers.
T. Suzuki et al., Journal of Physics; Conference Series 32( 2006 )309.
A. Dari et al., Classical and Quantum Gravity 27( 2010 )045010.
Plan : Measurement of thermal resistance and so on.

5. Sapphire suspension
Assembled sapphire monolithic suspension
Performance of assembled monolithic sapphire pendulum must be checked .
Before that , sapphire bulk is suspended by sapphire fibers using indium as thermal and mechanical contact
(some kinds of “glue” instead of bonding) between sapphire bulk and fibers.
We will investigate performance and obtain expertise for the monolithic pendulum test as first step .

5. Sapphire suspension
Assembled sapphire monolithic suspension
A. Khalaidovski is designing the frame for this first step .

6. Human resources
Fresh persons
Dr. Aleksandr Khalaidovski from Hannover, June 2013-May 2014
Sapphire monolithic suspension
(Dr. Fabián Erasmo Peña Arellano from Birmingham, May 2013 – April 2016
Cryogenic sensor)
Dr. Rahul Kumar from Glasgow, October 2013 – September 2014
Simulation and development of payload

6. Human resources

6. Human resources
Visitors supported by ELiTES in the last half year
Christian Schwarz, Gerd Hofmann, Ronny Nawrodt ( Jena )
Automatic systems to measure Q-values and thermal conductivity of sapphire fibers
Luca Naticchioni, Maurizio Perci, Ettore Majorana ( Rome )
Measurement of KAGRA radiation shield at cryogenic temperature
(Kieran Craig ( Glasgow )
Measurement of coating mechanical dissipation)

6. Human resources
Japanese graduate students visited (or will visit) Europe.
Yusuke Sakakibara (October 2012 – December 2012)
Investigation for coating and sapphire fibers
( Glasgow and Jena )
ET meeting, Hannover, December 2012 http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=1420 http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=1469
(Takanori Sekiguchi (January 2013 – March 2013)
Investigation for vibration isolation ( Amsterdam ) http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=1708
)
Dan Chen (September 2013 – October 2013)
Investigation for sapphire fiber ( Rome )

7. Summary
KAGRA cryostat
Three cryostats were transported to Kamika.
Test for KAGRA cryostat temselves
Experiment : Initial cooling time of payload
Radiation shield vibration
Yusuke Sakakibara and Dan Chen will explain details later.
Cryoduct
Preparation for experment
Yusuke Sakakibara will explain details later.
1/4 cryostat to check cryogenic payload will be delivered by the end of September .
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7. Summary
Sapphire monolithic suspension
Drilled bulk will be delivered on 16th of August .
Experiments for sapphire fiber and sapphire bonding are in progress but the results are promising .
We are preparing the first step experiment of monolithic sapphire suspension .
Human resources
Brilliant fresh persons
Strong support from ELiTES
Young Japanese researchers visit Europe.
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7. For future
Some items for future research (not perfect list)
(a)Investigation material properties
(Q, thermal conductivity, strength etc.) of coating, fiber and so on.
(b)Sapphire bonding, Sapphire fiber clamp
(c)Control and damping scheme
Actuators and sensors at cryogenic temperature
(d) Mechanical and thermal simulation for payload
(e) Vertical spring in cryostat
(f) Reduction of initial cooling time
Thermal resistance of clamp ....
(g) Baffles for scattered light in radiation shield
(h) Assembly procedure

8. Summary
Cryostat : Assembly is in progress.
Cooling test is coming soon .
Cryogenic duct : Optimum position of 5 buffles
Cryocooler unit :
Future work : scattered light
Cooling test and vibration measurement : OK
Cryogenic payload
Preparation for 1/4 cryostat to check payload performance is in progress .
Current main R&D topics
Inital cooling time, Sapphire fiber with nail head,
Coating mechanical loss, Vibration of shield
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8. Summary
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(1)How to assemble
Details of construction, clean room ….
(2)Strength
Tensile strength, development of clamp, sapphire bonding …
(3)Control and damping system to reduce fluctuation and instability
Actuators (what and where), resonant mode (frequency and Q) and so on
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(4)Cooling
Temperature of mirror (below 20 K), initial cooling time, heat resistance of clamp …
(5)Noise
Thermal noise, vibration via vibration isolation system and heat links …
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Cooling test in Toshiba
Test 2 : Heat load test
How much is temperature with extra heat load ?
We can derive extra heat load from temperature.
Examples for extra heat load
Scattered light by mirror
Heat absorption in mirror
300 K radiation through holes for main beam

Cooling test in Toshiba
Test 2 : Heat load test
Heater and thermometer
Pulse tube cryocoolers
Pulse tube cryocoolers
Sapphire mirror
Pulse tube cryocoolers

Cooling test in Toshiba
Test 2 : Heat load test
0 W
10 W
5 W
2 W
Scatted power is 5 W when scattered loss on the mirror surface is 10 ppm .

Cooling test in Toshiba
Test 2 : Heat load test
Heater and thermometer
Pulse tube cryocoolers
Pulse tube cryocoolers
Sapphire mirror
Pulse tube cryocoolers

Cooling test in Toshiba
Test 2 : Heat load test
0 W 10 W
4 W
According to our design, temperature should be below 8 K when heat absorption in mirror is 1 W .

2. 1/4 cryostat
Bid (for parts of 1/4 cryostat) was opened !
(Jecc Torisha)
Discussion for final design is in progress .
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4. Sapphire fibers
After Yusuke left …. Clamp for IMPEX fibers in Jena
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4. Sapphire fibers
Profile measurement in Glasgow
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5. Sapphire suspension
Sapphire fibers with nail heads
Q measurement in Jena
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5. Sapphire suspension
Sapphire fibers with nail heads
Thermal conductivity measurement in Jena
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5. Sapphire suspension
Sapphire fibers with nail heads
Latest summary
Crystal axis
Ribbon ?
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