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

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

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

Contents

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).

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

1. Introduction

1. Introduction 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

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)

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

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

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

(4)Cooling Initial cooling time simulation (Y. Sakakibara) Radiation is effective.

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

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.

Virgo+　　

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

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)

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

Part on surface of mirror (T. Suzuki)

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

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.

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