Sapphire Q measurement meeting

2023 August 3 13:30-15:00

Aso, Dan, Bajpai, KYamamoto, Komori, Yamada, Tomaru, Suzuki, Miyoki, Ushiba, Uchiyama

We discussed A/I in the previsou meeting (3 topics).


(1)KYamamoto : Evaluation of Q by residual gas damping
According to his Ph.D. thesis and Numata's master thesis, Q by residual gas is on the order of 10^9 or 10^10
even if the pressure is 1 Pa. It does not matter.


(2)Ushiba and Aso : Sapphire mirror stock checks at Kashiwa and Mitaka

Yoichi Aso found ETMX spare mirror at Mitaka.
Ears, no coating, all surfaces are polished, no magnets and spacers  
-> This bulk is necessary for Birefringens measurement. But it does not take time so long.

ETMY 
Takafumi Ushiba did not find it at Kashiwa.
He found some bulks but barrel surface is not polished (flat surfaces are polished).
-> Maybe, only spare ETMX and Y are suitable bulks for our measurement.

ETMY optical absorption measurement was conducted at Kashiwa. Then it was sent to somewhere 2021 April.
Matteo or Simon brought ? -> After this meeting, finally, Yoichi Aso found at Mitaka. We can use it.

Okamoto kogaku has polished test sample. 


(3)Yamada and Suzuki : Design of experimental apparatus

Tomohiro Yamamda shows design and outlines of measurement system.

CLIK with optical table area near cryocooler.

Window diameter is 80mm. 
Center of mirror is 10cm higher than center of window.
Cu screws support bottom plate.

Tungusten wires (0.4mm or 0.5mm in diameter) is necessary. 
(TAMA mirror is 1kg was suspended by tungsten wires (0.05mm diameter. So 0.25mm diamater is OK. But we are on safe side.)
Upper side of the wire is on the slit in a bar (stand off like). But friction could be an issue. 
-> Bar is removed and the end of wire is clamped.
Other points of stand off
Stand off is necessary to avoid dropping. It is easier to suspend buik with stand off.
Sapphire or hard material is necessary (aluminum is OK) for stand off.
-> Yoich asks R.Takahashi-san whether we have spare stand off (wire breaker) and design drawing of stand off.

Electrostatic actuator : 1mm gap is enough. -> Anyhow, Earthquake stopper is necessary.

Tension adjustment system is included in Tomohiro's design.

Budget => Miyoki-san considers.

Which mode is measured ? -> 24kHz and 34 kHz are axis symmetric mode.

Some jig for installation and earthquake stopper is necessary. But we need not to use HCB box.


Before new ITM HCB, we would like to identify cause, at least.
Fiber must be also investigated (Rishabh)

Our next meeting will be on week of 21st of August.
Monday is not possible. Kazuhiro circulate doodle later.