1. Cryo-payload Suspension structure
Kazuhiro Yamamoto
Institute for Cosmic Ray Research (ICRR)
the University of Tokyo
KAGRA face to face meeting　　　
Institute for Cosmic Ray Research, The University of Tokyo,
Kashiwa, Chiba, Japan
14 February 2014

2. Contribution
R. Takahashi, K. Ono, T. Sekiguchi, Y. Sakakibara, C. Tokoku,
M. Kamiizumi, U. Iwasaki, E. Hirose, A. Khalaidovski, R. Kumar,
T. Uchiyama, S. Miyoki, M. Ohashi, K. Kuroda, T. AkutsuA, H. IshizakiA,
F. E. Peña ArellanoA, T. SuzukiB, N. KimuraB, S. KoikeB, T. KumeB,
K. TsubonoC, Y. AsoC, T. UshibaC, K. ShibataC, D. ChenD, N. OhmaeE,
K. SomiyaF, R. DeSalvoG, E. MajoranaH, L. NaticchioniH, W. JohnsonI,
A. CummingJ, R. DouglasJ, K. HaughianJ, I. MartinJ, P. MurrayJ,
G. HammondJ, S. RowanJ , G. HofmannK, C. SchwarzK, D. HeinertK,
R. NawrodtK, S. GotoL, M. TanakaL, S. IokaM, K. NakamotoM, H. NezukaM, KAGRA collaboration
ICRR.UT, NAOJA, KEKB, Phys.S.UTC, Astro.S.UTD, E.UTE,S.TITF,
Sannio Univ.G, INFNH, Louisiana State Univ.I , University of GlasgowJ, Friedrich-Schiller-Universitaet JenaK, Jecc TorishaL,
Toshiba Keihin Product OperationsM, KAGRA collaboration

3. 0. Abstract Although there are many topics, here, I will explain
(1)Schedule
(2)Overall design
(3)Monolithic sapphire suspension
(4)Heat links

4. Contents
Introduction
Schedule
Overall design
Sapphire suspension
Heat links
ELiTES activity
Summary

5. 1. Introduction Schematic view of KAGRA interferometer
Four mirrors of arm cavity will be cooled.
3km
3km
Mozumi
Y-end
Sakonishi
X-end
Kamioka mine
(Underground site)
Atotsu
Center
Vibration isolation system, Cryocooler unit, Cryostat, Cryogenic payload 5 5 5 5

6. 1. Introduction
Outline of vibration isolation and cryostat
14 m 6

7. 1. Introduction Outline of vibration isolation and cryostat 14 m
Cryogenic mirror 7

8. 1. Introduction Outline of cryostat Cryogenic payload Mirror S. Koike
to SAS
Cryogenic payload
Cryostat
Stainless steel t20mm
Diameter 2.6m
Height ~3.6m
M ~ 10 ton
Mirror
View ports
4 Low vibration
cryocooler unit
Cryo-coolers
Pulse tube, 60Hz
0.9 W at 4K (2nd)
36 W at 50K (1st)
Main LASER beam
Remote
valve unit
S. Koike

9. Outline of vibration isolation and cryostat
Heat link (pure Al)
Heat link (pure Al)
Pulse tube cryocoolers
Pulse tube cryocoolers
Sapphire fiber
Sapphire mirror (About 20K)
Pulse tube cryocoolers 9 9 9 9

10. 1. Introduction Schematic view of cryogenic payload Platform
Intermediate
Recoil Mass
Intermediate Mass
Test Mass (sapphire mirror)
Recoil Mass

11. 1. Introduction Outline of cryogenic payload Design is in progress.
Details should
be changed.
Intermediate
Recoil Mass
Intermediate Mass
Test Mass (sapphire mirror)
Recoil Mass

12. 1. Introduction Outline of cryogenic payload in radiation shield

13. 1. Introduction “Sapphire monolithic suspension”
One of the most important
parts of KAGRA :
Main sapphire mirrors
are included.
All parts are made
from sapphire.
Details should be changed.
Mirror

14. 2. Schedule “Official plan”
End of 2017 : Cryogenic interferometer operation
This is the significant milestone of KAGRA.
Delivery of cryogenic payload
By March 2015, One payload
By March 2016, Three payloads
For sapphire monolithic suspension, so aggressive !
The suspensions will be improved step by step.
Initial phase suspension before final phase one is necessary.

15. 2. Schedule “Initial phase” Larger thermal noise but more feasible
First cryogenic payload (2014)
is a “Initial phase”.
R&D for final phase
should be in progress at the same time.
　　Otherwise, thermal noise
can not be reduced.
We must do our best for
three payloads as final phase (2015).

16. 2. Schedule “Initial phase”
Although thermal noise is large, it should be cooled (heat load test is necessary).
It should be as simple as possible (budget and human resources).
It can be replaced by final phase sapphire monolithic suspension later. 16 16 16

17. 2. Schedule There are some ideas for “Initial phase”
(1)No bonding, but screws, indium, cradle
(2)Thick tungsten wires
(they transfer heat)
R&D for these plans must
be finished and we select
an idea by May 2014.
Indium 17 17 17 17

18. 3. Overall design
Not sapphire suspension, but cryogenic payload in total
Takanori Sekiguchi and Eiichi Hirose visited Stanford (December 2013) to discuss overall design with control system.
Design and discussion are in progress.
Preliminary design document 18 18 18 18

19. 3. Overall design E. Hirose organizes team to design
the first cryogenic payload
(Member : E. Hirose, T. Sekiguchi,
R.Takahashi, R. Kumar).
Dead line is June 2014.
Short meeting every morning
Some figures in 1. Introduction are brought by this team. 19 19 19 19

20. 4. Sapphire suspension Sapphire monolithic suspension
R&D for components are
in progress.
There are a lot of items.
Here,
(1)Sapphire fiber
(2)Sapphire blade spring
(3)Sapphire bonding
are introduced. 20 20 20 20

21. 4. Sapphire suspension
Sapphire fibers with nail heads are necessary to suspend mirrors.
Test sample (T. Uchiyama) 21

22. 4. Sapphire suspension MolTech GmbH IMPEX HighTech GmbH
Sapphire fibers with nail heads
MolTech GmbH (Germany) and IMPEX HighTech GmbH (Germany) have already delivered !
MolTech GmbH
IMPEX HighTech GmbH 22 22

23. 4. Sapphire suspension Sapphire fibers with nail heads
Quality check under collaboration with ET (ELiTES)
Q-value
Measurement in Glasgow, Jena, Rome and Tokyo
Thermal conductivity
Measurement in Jena, Rome and Tokyo
Strength
Measurement in Glasgow

24. 4. Sapphire suspension IMPEX fibers satisfy the KAGRA requirement.
Sapphire fibers with nail heads
Latest summary of Q and thermal conductivity
Moltech IMPEX KAGRA
requirement
Q-value * *106
at 20K *106
Thermal
Conductivity
at 20K [W/m/K]
IMPEX fibers satisfy the KAGRA requirement.

25. 4. Sapphire suspension Sapphire fibers with nail heads
Q of IMPEX fiber (D. Chen)
Requirement : 5*106

26. 4. Sapphire suspension Sapphire fibers with nail heads
Thermal conductivity of IMPEX fiber
arXiv:

27. 4. Sapphire suspension Sapphire fibers with nail heads
Paper about thermal conductivity measurement was submitted to Classical and Quantum Gravity.
arXiv:

28. 4. Sapphire suspension Sapphire fibers with nail heads
Strength test in Glasgow
Fiber suspended weight. Moreover, weight was swung or pulled.
Broken jointed end
Broken jointed end
15kg test hang

29. 4. Sapphire suspension Sapphire fibers with nail heads
Strength test in Glasgow
Fiber suspend weight. Moreover, weight was swung or pulled.
G. Hammond reported in ELiTES meeting
(December 2013).
Safety factor derived from measurement :
Broken jointed end
E. Majorana will visit Glasgow in this month and try strength test.

30. 4. Sapphire suspension Sapphire fibers with nail heads
Although we investigated fibers with round nail heads …
Flat surfaces are necessary for bonding.
New fibers with square nail head (IMPEX) is coming soon (end of February) !
Our plan for these fibers
Surface flatness check (less than l/10 (l=630nm))
Measurement of thermal conductivity and Q

31. 4. Sapphire suspension Sapphire blade spring Sapphire fibers are thick
(1.6 mm in diameter)
for heat transfer.
Stretch by sapphire mirror
weight (23kg) : 21 mm
If difference between length
of 4 fibers are larger than 21 mm,
there is no tension in one fiber !
Blade spring is necessary.

32. 4. Sapphire suspension Sapphire blade spring (design is in progress)
46 mm
R. Kumar
Vertical resonant
frequency : 17.4 Hz
Max. stress : 159 MPa
Bending breaking stress
:300 MPa
(G. Hammond reported
in ELiTES meeting
90 mm

33. 4. Sapphire suspension Bonding between sapphire fibers
and sapphire mirror
Hydroxide Catalysis Bonding (AdLIGO and Virgo)
If fibers are broken, bonding parts must be taken apart …
Candidates : Indium, Optical contact, Screws
Test (in progress or near future plan)
Strength test (tensile and shear) : KEK
Thermal resistance : ICRR
Mechanical dissipation : Jena and Glasgow
(ELiTES) 33

34. 4. Sapphire suspension Bonding between sapphire fibers
and sapphire mirror
Hydroxide Catalysis Bonding
Rebecca reported in ELiTES meeting (Dec. 2013). 34

35. 4. Sapphire suspension Bonding between sapphire fibers
and sapphire mirror
Hydroxide Catalysis Bonding
(Rebecca Douglas[Glasgow],
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)
Rebecca Douglas and Karen Haughian stayed in Japan in the last autumn.
Rebecca reported in ELiTES meeting (Dec. 2013). 35

36. 4. Sapphire suspension Rebecca Douglas and Karen Haughian
HCB Shear strength test
(Strength vs crystal direction)
Preliminary 36

37. 4. Sapphire suspension Next HCB shear strength test is in progress. 37 37

38. 4. Sapphire suspension Indium
If fibers are broken, bonding parts must be taken apart …
Indium is one of candidates.
Hot welding
Foil or evaporation (thickness: <20 mm)
are prepared and heat is applied.
When bonding parts are taken apart, heat and acid are applied. 38

39. 4. Sapphire suspension
We are preparing sample (KEK) … 39

40. 4. Sapphire suspension
We are preparing sample (KEK) … 40

41. 4. Sapphire suspension
We are preparing sample (KEK) … 41

42. 4. Sapphire suspension
We are preparing sample (KEK) … 42

43. 4. Sapphire suspension
We are preparing sample (KEK) … 43

44. 4. Sapphire suspension R&D for integration of components
One fiber prototype
Full prototype 44

45. 5. Heat links Outline of vibration isolation and cryostat
Heat link (pure Al)
Heat link (pure Al)
Pulse tube cryocoolers
Pulse tube cryocoolers 45 45 45 45

46. 5. Heat links Heat links must be thick and short as heat path.
However they must be thin and long as vibration path !
Dan Chen reports vibration via heat link in the next talk.
Yusuke Sakakibara explains initial cooling time of cryogenic payload at the first talk in this afternoon. 46

47. 6. ELiTES activities ELiTES: ET-LCGT interferometric Telescope
Exchange of Scientists
Grant for collaboration about cryogenic
between KAGRA and ET
European 7th Framework Programme
Marie Curie action (Mar Feb. 2016)
European people can visit Japan
for KAGRA. 47

48. 6. ELiTES activities A total of 25 visitors supported
by ELiTES in 2013
Note : Short stay for meeting is not counted.
Germany (A total of 8 persons)
Jena (A total of 6 persons), Hannover (2 persons)
Netherlands NIKHEF (2 persons)
United Kingdom Glasgow (3 persons)
Italy (A total of 12 persons)
Rome (3 persons), Sannio (A total of 9 persons) 48 48 48

49. 6. ELiTES activities ELiTES in 2014 has already started !
Ettore Majorana (Rome) : Last week !
Discussion for cryogenic payload
and vibration isolation
Ronny Nawrodt and Stefanie Kroker (Jena) arrived this morning !
Cryogenic experiment 49 49 49

50. 7. Summary Schedule Schedule is quite aggressive.
We need initial phase suspension.
Later it will be replaeced by final phase one.
Design of initial phase suspension should
be finished by next May.
Overall design
Discussion with Stanford
Small team for design
(short meeting every morning)
Preliminary design document

51. 7. Summary Sapphire suspension Research and development for components
(quality checks of fibers, design of blade spring,
test for many kinds of bonding) are finished or
in progress.
New fibers with square nail heads
will be delivered at the end of February.
Heat link
Dan Chen (vibration) and Yusuke Sakakibara
(initial cooling time) report later.
ELiTES
A total of 25 visitors in 2013.
So far, 3 visitors in 2014.

52. Thank you for your attention !

53. 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
The next topic is the vibration of shield. Takanori Sekiguchi calculated the vibration via heat links. Takanori assumed that vibration of heat link anchor in the radiation shield is the same as that of CLIO. But, this vibration depends on the structure of shield. So, Luca from Rome and Chen Dan will measure vibration of radiation shield of KAGRA cryostat on this autumn. Luca and Chen will measure the vertical and horizontal motion. Here, I would like to introduce Chen Dan’s activity for horizontal motion. 53

54. 8. Summary Cryostat : Assembly is in progress.
Cooling test is coming soon.
Cryogenic duct : Optimum position of 5 buffles
Future work : scattered light
Cryocooler unit :
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
This is the summary. Design and discussion for ¼ cryostat is in progress. Sapphire fibers with nail head can be provided by Moltech and IMPEX. These R&D items are investigated. Other ideas for mirror suspension were proposed. Collaboration with ELiTES in progress and I hope the collaboration with university of Toyama will established near future.

55. 2. Issues (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
This is the issues for development of cryogenic payload; how to assemble and install, strength, control and damping system to reduce fluctuation and instability, cooling and noise.

56. 2. Issues (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 …
This is the issues for development of cryogenic payload; how to assemble and install, strength, control and damping system to reduce fluctuation and instability, cooling and noise.

57. 4. Sapphire fibers After Yusuke left …. Clamp for IMPEX fibers in Jena
Ok, we must check the quality of these fibers. Now, Takafumi Ushiba and Kazunori Shibata proceed with measurement of thermal conductivity and Q-values of sapphire fibers, respectively.

58. 4. Sapphire fibers Profile measurement in Glasgow
Ok, we must check the quality of these fibers. Now, Takafumi Ushiba and Kazunori Shibata proceed with measurement of thermal conductivity and Q-values of sapphire fibers, respectively.

59. 5. Sapphire suspension Sapphire fibers with nail heads
Q measurement in Jena
Ok, we must check the quality of these fibers. Now, Takafumi Ushiba and Kazunori Shibata proceed with measurement of thermal conductivity and Q-values of sapphire fibers, respectively.

60. Outline of vibration isolation and cryostat
Vacuum chamber
(300K)
Inner shield
(8K)
Outer shield
(80K)
Pulse tube cryocoolers
2 Pulse tube cryocoolers
OK, what is cryogenic payload ? This is the cross section of tunnel of LCGT. This tall tower is vibration isolation system. There is cryogenic payload under this vibration isolation. Cryogenic payload is in cryostat. Payload includes mirror, which is the most important part of gravitational wave detector.
2 Pulse tube cryocoolers
Baffles Cryoduct 60 60 60 60 60 60