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K. Yamamoto, R. Takahashi, T. Sekiguchi, T. Uchiyama, H. IshizakiA, A. TakamoriB, R. DeSalvoC, E. MajoranaD, LCGT collaboration

ICRR, NAOA,ERIB, Sanio UnivC., INFND

Development of vibration isolation systems

for LCGT VI

2011 September 18The meeting of Physical Society of Japan

@Hirosaki University, Aomori

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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

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0. Abstract

Cryogenic part (cryogenic payload) of seismic isolation system for LCGT project

Room temperature part has already reported by R. Takahashi.

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Contents

1.Introduction2.Issues3.Current status4.Summary5.Future work

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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 instabilityK. Yamamoto, Journal of Cryogenics and Superconductivity Society of Japan 46 (2011) 426 (in Japanese).

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1. Introduction

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Cryogenic mirror

Cryostat

Vibration Isolation(Type A)

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1. Introduction

Sapphire mirror(20K)

Sapphire fiber

Shield(8K)

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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

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(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

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(4)Cooling

Temperature of mirror, initial cooling time, heat resistance …

(5)Noise

Thermal noise, vibration via heat links …

2. Issues

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(1)Thermal simulation for cooling

Collaboration with Rome University Astroparticle Physics 35(2011)67.

Thermal simulation for Einstein Telescope (3rd generation in Europe) cryogenic payload

Cross check

3. Current status

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(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

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(1)Thermal simulation for cooling Initial cooling time simulation (Y. Sakakibara)

Radiation is effective.

3. Current status

Shield

Mirror

Platform

Intermediate mass

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(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

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(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

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Virgo+ 　　

3. Current status(2) Monolithic sapphire mirror suspension 　

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Part on end of fiber 　　

One company can provide it (Uchiyama).Uchiyama asks another company. 　　

3. Current status(2) Monolithic sapphire mirror suspension 　

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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 　

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Part on surface of mirror 　　

(T. Ushiba, K. Shibata, T. Suzuki)

3. Current status(2) Monolithic sapphire mirror suspension 　

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3. Current status(2) Monolithic sapphire mirror suspension 　

Part on surface of mirror 　　

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(3)Noise

Angular fluctuation by external vibration (via heat link) : T. Sekiguchi’s talk

Thermal noise : K. Somiya’s talk

3. Current status

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Cryogenic payload : One of key features of LCGT projectCryogenic 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

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(1)How to assemble Details of construction, clean room ….

(2)Control system Actuators (what and where), resonant mode (frequency and Q)

5. Future work

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(T. Suzuki)