New coating material meeting 

10:30- 11:20 (CET) 17:30-18:20 (JST) 2021 April 27 (Tue)

Attendees
Cagnoli, Granata, Cesarini, Leonardi, Nakayama, Pinard, Bazzani, Yamamoto

June or July 2021 : LV decide new coating.

KAGRA: In any case, we need new coating on ITM to reduce the difference of 
the reflectances (current bulks of ITM's can be used).

Then full size path finder mission starts. But first of all, LMA has to prepare something for 
grand coater. The first test would be end of autumn (let see what happens).
If grant coater works, 100mm diameter coating is not issue.

Before the delivery, and when we have time, we try to measure other material coating. 
(Toyama can start on summer ?)
But in such cases, 75mm diameter sapphire disk is better.

So as first step Toyama group try to measure Q of 75mm diameter sapphire disk.

Concerns of SiN is high power absorption (mechanical loss itself is small)
In the case of Ge, we ask, for example, Glasgow ?.



Young's modulus from Massimo

thremelastic damping of sapphire disk to Elisabetta