1. 1 Kazuhiro Yamamoto Institute for Cosmic Ray Research The university of Tokyo Report from sub-groups Cryogenic Cryogenic payload 4 August 2011

2. 2 What is cryogenic payload ? Cryogenic mirror Cryostat Vibration Isolation

3. 3 What is cryogenic payload ?

4. 4 An essenstial part of cryogenic interferometer (This includes main mirror !) Border between vibration isolation and cryogenic sub-groups Kazuhiro Yamamoto is assigned to manage the development of cryogenic payload.

5. 5 What is our plan (in long term) ? (1)Prototype cryostat and payload (-March 2013(construction), Kashiwa) Main target : test of cooling However, almost all fundamental items should be checked using this prototype. (2)Test in LCGT cryostat (Kamioka mine)

6. 6 What is our plan (in long term) ? Prototype cryostat and payload (-March 2013(construction), Kashiwa) Budget : A part of Leading Edge Research Program We must make effort to obtain more budget. Any supports are welcomed. International collaboration Europe (IRSES program, Einstein Telescope) USA (Proposal is in progress) Kazuaki Kuroda reported the details yesterday.

7. 7 (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 ?

8. 8 (4)Cooling Temperature of mirror, initial cooling time, heat resistance of clamp … (5)Noise Thermal noise, vibration via heat links … What are issues ?

9. 9 What is our plan (in short term) ? (1) First design of cryogenic payload Motivation : Basis of discussion of development for payload Collaboration with Rome group They have some results for Einstein Telescope. Astroparticle Phyics 35 (2011) 67. Informal meeting with Rome group (8 July 2011)

10. 10 (1) First design of cryogenic payload The first step is thermal simulation. Mirror temperature with high power light Initial cooling time Cross check with Rome Parameters of Rome group have already arrived. Thermal simulation using finite element method (by Shigeaki Koike (KEK)) Analytical thermal simulation (by Yusuke Sakakibara(ICRR), the details are introduced in his talk) What is our plan (in short term) ?

11. 11 What is our plan (in short term) ? (2) Fiber-Mirror bonding One of the most important issues Although we have investigated, the progress of development should become rapid. Strength test : Toshikazu Suzuki (KEK) Measurement of thermal resistance : Kazunori Shibata, Takafumi Ushiba (Department of Physics, University of Tokyo)

12. 12 What is our plan (in short term) ? (3) Coating mechanical loss at low temperature We have already investigated coating by Japan Aviation Electronics Industry, Ltd. Physical Review D 74 (2006) 022002. However, they do not provide any coating now. We should start to search coating company and measure mechanical loss again … Eiichi Hirose(ICRR)

13. 13 What is our plan (in short term) ? (3) Coating mechanical loss at low temperature Latest result …. (KEK,26 July 2011)

14. 14 Summary (1)Long term plan Prototype experiment in Kashiwa Construction by March 2013 Test in LCGT cryostat (Kamioka) (2)Short term plan First design of cryogenic payload Thermal simulation is in progress. Fiber-Mirror bonding Fresh persons joined. Coating mechanical loss at low temperature Preparation is started.