1. 1 K. Yamamoto, R. Takahashi, T. Sekiguchi, T. Uchiyama, H. Ishizaki A, A. Takamori B, R. DeSalvo C, E. Majorana D, LCGT collaboration ICRR, NAO A,ERI B, Sanio Univ C., INFN D Development of vibration isolation systems for LCGT VI 2011 September 18 The meeting of Physical Society of Japan @Hirosaki University, Aomori

2. 2 And other people join … K. Kuroda, M. Ohashi, S. Miyoki, C. Tokoku, M. Kamiizumi, U. Iwasaki, Y. Sakakibara, T. Akutsu A, T. Suzuki E, N. Kimura E, S. Koike E, K. Tubono F, Y. Aso F, T. Ushiba F, K. Shibata F, N. Ohmae G, K. Somiya H ICRR, NAO A,ERI B, Sanio Univ C., INFN D, KEK E, Dept. Phys.,Univ. Tokyo F, Dept. Appl.Phys., Univ. Tokyo G, TITech H

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

4. 4 Contents 1.Introduction 2.Issues 3.Current status 4.Summary 5.Future work

5. 5 1. Introduction LCGT (Large-scale Cryogenic Gravitational Wave Telescope) 2nd generation interferometric detector in Japan 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. 6 1. Introduction 6 Cryogenic mirror Cryostat Vibration Isolation (Type A)

7. 7 1. Introduction Sapphire mirror (20K) Sapphire fiber Shield (8K)

8. 8 Schedule of LCGT iLCGT (room temperature) ~2014.9 bLCGT (cryogenic temperature) 2014.10~ Cryostat installation in ICRR (Kashiwa) ~2013.3 (Check of cryostat system) Check of cryogenic payload in ICRR Design of cryogenic payload ~ 2012.3 1. Introduction

9. 9 (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) 2. Issues

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

11. 11 (1)Thermal simulation for cooling Collaboration with Rome University Astroparticle Physics 35(2011)67. Thermal simulation for Einstein Telescope (3 rd generation in Europe) cryogenic payload Cross check 3. Current status

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

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

14. 14 (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 DLC enhances radiation effect. 3. Current status Shield

15. 15 (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. 3. Current status

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

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

18. 18 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) 3. Current status (2) Monolithic sapphire mirror suspension

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

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

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

22. 22 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 external vibration (with heat link) (4)Thermal noise 4. Summary

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

24. 24 (T. Suzuki)