1. 1 Kazuhiro Yamamoto Institute for Cosmic Ray Research The university of Tokyo Bulk materials, coating materials for KAGRA ELiTES WP2 meeting 15 June 2012

2. 2 Mirror and suspension of KAGRA Sapphire mirror Ta 2 O 5 /SiO 2 coating without TiO 2 doping Sapphire fibers to suspend the mirrors Connection between fibers and mirror

3. 3 Sapphire mirror Vendor : Crystal Systems. Inc. Most serious problem : Absorption Requeirement : < 20 ppm/cm K. Watanabe is measuring absorption.

4. 4 Sapphire mirror Vendor : Crystal Systems. Inc. Scattering Extra head load on recoil mass ?

5. 5 Sapphire mirror Vendor : Shanghai Institute of Ceramic They can provide larger bulks. But we should check the quality (absorption, thermal conductivity, Q-values...)

6. 6 Coating Vendor : ? We measured JAE coating. Although JAE made coating on TAMA mirrors, they withdrew from their business of coating. We must look for other vendor and measure coating loss (and other mechanical and optical properties ?). Eiichi Hirose proceeds with the experiment for mechanical loss.

7. 7 Coating This is only my opinion. There is the discrepancy between the results of Glasgow (peak around 20K) and KAGRA (no peak). If ELiTES can solve this problem, it is great.

8. 8 Sapphire fibers

9. 9 Sapphire fibers to suspend sapphire mirrors Sapphire fibers from MolTech GmbH (Germany) We ordered similar fibers (IMPEX GmbH, Germany). Or other vendor ?

10. 10 Sapphire fibers We should check quality. Thermal conducitivity : T. Ushiba Q-values : K. Shibata Strength : ?

11. 11 Connection between fibers and mirrors Ears are necessary. Bonding ? Drilling or shaving on the sapphire mirror Ears

12. 12 Bonding 12 Sapphire fibers to suspend sapphire mirrors Bonding (between sapphire fibers and mirrors) There are many candidates. Thermal conductivity (Ushiba?), Q-values (Shibata?) and strength (who?) should be checked. Metalize bonding (Kyocera)

13. 13 Bonding We have a device for shear strength test.

14. 14 Bonding Although T. Suzuki has already investigated, we do not know solution. Especially, Q has never been measured !

15. 15 Other ideas for suspension Composite mirror suspension (R. DeSalvo) Thin support wires and soft heat links (W. Johnson)

16. 16 What are topics about collaboration ? There are so many items, but, in almost cases, (1)Optical absorption (2)Thermal conducutivity (3)Strength (4)Q-values at cryogenic temperature. In many cases, samples are not so large. So, we can measure everywhere if there is the apparatus. We can summarize results as papers.

17. 17 What are topics about collaboration ? We must look for vendors to provide sapphire fibers with thick ends. Could you look for together ? In fact, only two German companies said that yes they can. So, I expect that hope is in Europe....

18. 18 What are topics about collaboration ? Of course, we should dicuss the details.