1. Development of vibration isolation systems for LCGT VI
K. Yamamoto, R. Takahashi, T. Sekiguchi, T. Uchiyama, H. IshizakiA,
A. TakamoriB, R. DeSalvoC, E. MajoranaD, LCGT collaboration
ICRR, NAOA,ERIB, Sanio UnivC., INFND
At first, thank you for giving a chance talk here. In fact, I have been in Trento in 2002, eight years ago. I am happy because I can visit here again. OK, shall we start ? This is the title of my talk of today. Gravitational wave and detectors.
2011 September 18
The meeting of Physical Society of Japan
@Hirosaki University, Aomori

2. And other people join …
K. Kuroda, M. Ohashi, S. Miyoki, C. Tokoku, M. Kamiizumi, U. Iwasaki,
Y. Sakakibara, T. AkutsuA, T. SuzukiE, N. KimuraE, S. KoikeE,
K. TubonoF, Y. AsoF, T. UshibaF, K. ShibataF, N. OhmaeG, K. SomiyaH
ICRR, NAOA,ERIB, Sanio UnivC., INFND, KEKE , Dept. Phys.,Univ. TokyoF , Dept. Appl.Phys., Univ. TokyoG , TITechH

3. 0. Abstract Cryogenic part (cryogenic payload)
of seismic isolation system
Room temperature part has already reported
by R. Takahashi.

4. Contents
Introduction
Issues
Current status
Summary
Future work

5. 1. Introduction
LCGT (Large-scale Cryogenic Gravitational Wave Telescope)
2nd generation interferometric detector
Cryogenic system : One of key features of LCGT project
Reduction of thermal noise,
thermal lens, and parametric instability
K. Yamamoto, Journal of Cryogenics and Superconductivity Society of Japan
46 (2011) 426 (in Japanese).

6. 1. Introduction Vibration Isolation (Type A) Cryostat Cryogenic mirror6

7. 1. Introduction

8. 1. Introduction Schedule of LCGT iLCGT (room temperature) ~2014.9
bLCGT (cryogenic temperature) ~
Cryostat installation in ICRR (Kashiwa) ~2013.3
(Check of cryostat system)
Check of cryogenic payload in ICRR
Design of cryogenic payload ~

9. 2. Issues (1)How to assemble Details of construction, clean room ….
(2)Strength
Tensile strength, development of clamp, …
(3)Control system
Actuators (what and where),
resonant mode (frequency and Q)

10. 2. Issues (4)Cooling Temperature of mirror, initial cooling time,
heat resistance …
(5)Noise
Thermal noise, vibration via heat links …

11. 3. Current status (1)Thermal simulation for cooling
Collaboration with Rome University
Astroparticle Physics 35(2011)67.
Thermal simulation
for ET cryogenic payload
Cross check

12. 3. Current status (1)Thermal simulation for cooling
S. Koike (KEK) tryies simulation with same
model using ANSYS.
Calculation
and discussion
are in progress …
1/2モデル 4K
Φ1mm　
Cu wire
ミラー中心に
直径35mmの
ビームがあたる
0.6m
Siミラー

13. 3. Current status (1)Thermal simulation for cooling
Initial cooling time simulation (Y. Sakakibara)
Intermediate mass
Platform
Mirror
Shield
Radiation is effective.

14. 3. Current status (1)Thermal simulation for cooling
Initial cooling time simulation (Y. Sakakibara)
DLC (Sakakibara’s talk)
on surface of masses
(except for mirror)
in payload and shield
Shield
DLC enhances radiation effect. 14

15. 3. Current status (2) Monolithic sapphire mirror suspension
Low mechanical loss, high thermal conductivity
Small thermal noise, effective cooling
Connection between mirror and fiber
If fibers are glued to mirror,
there are some problems
in process of polish and coating for mirror
and in the case of break of fibers.

16. 3. Current status
(2) Monolithic sapphire mirror suspension 　
Virgo+　　

17. 3. Current status (2) Monolithic sapphire mirror suspension
Part on end of fiber 　　
One company can provide it (Uchiyama).
Uchiyama asks another company. 　　

18. 3. Current status (2) Monolithic sapphire mirror suspension
Part on surface of mirror 　　
Bonding
Candidate : Surface-Activated
room-temperature Bonding(Ohmae),
Ceramic adhesion, Diffusion bonding,
Hydroxide-catalysis bonding
Measurement of strength and thermal resistance
in KEK (T. Ushiba, K. Shibata, T. Suzuki)

19. 3. Current status (2) Monolithic sapphire mirror suspension
Part on surface of mirror 　　
(T. Ushiba, K. Shibata, T. Suzuki)

20. 3. Current status (2) Monolithic sapphire mirror suspension
Part on surface of mirror 　　
(T. Suzuki)

21. 3. Current status (3)Noise Angular fluctuation by external vibration
(via heat link) : T. Sekiguchi’s talk
Thermal noise : K. Somiya’s talk

22. 4. Summary Cryogenic payload : One of key features of LCGT project
Cryogenic part of seismic isolation system
Cryostat installation in ICRR (Kashiwa) ~2013.3
(Check of cryostat system)
Check of cryogenic payload in ICRR
Preparation is in progress.
(1)Thermal simulation
(2)Sapphire fiber-mirror connection
(3)Simulation of effect of seismic motion (with heat link)
(4)Thermal noise

23. 5. Future work (1)How to assemble
Details of construction, clean room ….
(2)Control system
Actuators (what and where),
resonant mode (frequency and Q)