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 , Fac. Sci.,Univ. TokyoF , KEKG , KEKH

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

4. Contents

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. What are issues ? (1)How to assemble
Details of construction, clean room ….
(2)Strength
Tensile strength, development of clamp,
sapphire bonding …
(3)Control system
Actuators (what and where),
resonant mode (frequency and Q)

10. What are issues ? (4)Cooling
Temperature of mirror, initial cooling time,
heat resistance of clamp …
(5)Noise
Thermal noise, vibration via heat links …

11. (4)Cooling
Collaboration with Rome University
Astroparticle Physics 35(2011)67.
Thermal simulation
for ET cryogenic payload
Cross check

12. S. Koike (KEK) trys simulation with same model using ANSYS.
(4)Cooling
S. Koike (KEK) trys 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. (4)Cooling
Initial cooling time simulation (Y. Sakakibara)
Radiation is effective.

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

15. Connection between mirror and fiber
Monolithic sapphire mirror suspension　
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. Virgo+　　

17. Part on end of fiber 　　
One company can provide it (Uchiyama).　　

18. Part on surface of mirror 　　
Bonding
Candidate : Surface Activate Bonding (Ohmae)
Test of strength and thermal resistance in KEK
(T. Ushiba, K. Shibata, T. Suzuki)

19. Part on surface of mirror
(T. Ushiba, K. Shibata, T. Suzuki)

20. Part on surface of mirror
(T. Suzuki)

21. (5)Noise
Seismic noise (with heat link) : T. Sekiguchi’s talk
Thermal noise : K. Somiya’s talk

22. Summary Cryogenic payload : One of key features of LCGT project
Cryogenic part (cryogenic payload)
of seismic isolation system
Cryostat installation in ICRR (Kashiwa) ~2013.3
(Check of cryostat system)
Check of cryogenic payload in ICRR
Investigations for thermal simulation,
sapphire fiber-mirror connection,
simulation of effect of seismic motion (with heat link),
thermal noise are in progress.

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