Sapphire Q measurement meeting

2023 August 24 13:00-14:00

Aso, Dan, KYamamoto, RTakahashi, Aso, Suzuki, Miyoki 

(1)Stocks of bulks with ears
Two pieces were found at NAOJ. Marc would like to measure both of them. We expect that he will measure at least 
one of them before we prepare our apparatus.

(2)Offsite Q measurement
Yesterday and today, M. Yamamoto and Y. Sato (U Toyama), K. Komori (U Tokyo), K. Tanaka (ICRR) are measuring Q of 
ETMX (about 30K). We are afraid that AR side is covered by frost.

(4)Suzuki-san's  suggestion
(1)Short meeting (1 hour) -> At least this meeting ended within one hour. 
(2)We also take care of Q of sapphire fibers in this meeting (later).


(4)Mirror Q measurement (Yamada and Suzuki)

(a)Clamp : Wire inclination is 10 degree to avoid any bending of wire.

(b)Wire breakers
Other wire breakers, for example breakers on bottom side or smaller breaker on 
lower side -> RTakahashi pointed out smaller breakers were broken or dropped if he 
remember correclty.
A/I : Yamada asks Hirata-san details later.

Long breakers (2 pieces) or short breakers (4 pieces) ? 
-> Shorter ones to avoid effect on Q.
 
Distance between wires : According to N. Ohishi's master thesis (https://granite.phys.s.u-tokyo.ac.jp/theses/Ohishi-m.pdf),
the best distance between 2 loop wires for Q measurement is one third of mirror thicknes.
It implies that wires must be in slits of sapphire ears. However, the wire breaker 
could be larger (and Q might be lower).
A/I : Yamada and Suzuki check the size of breakers for wires in slits. 

Material wire breaker is stainless. Sapphire breaker lead time is long.

(c)Glue
Glue must be removed. What kinds of glue ? Are In or Ga feasible (this glue need 
not to support heavy load) (Dan's suggestions) ? -> We continue discussion.

(d)Earthquake stopper and Actuator
Yamada and Suzuki's idea is similar to HCB box. In HCB box, soft large parts touch HR
and screw touch AR to fix the mirror. In Q measurement, actuator electrode 
is on AR surface.To avoid collision of AR surface and electrode, soft large part is 
necessary on AR side. So, screw is on HR side. Is it OK ? Otherwise, screw touch on 
chamfer ?
-> D. Chen suggests the electrode on HR side which has hole for laser beam. 
Large soft part is on HR side and screw is on AR side as HCB box. -> We approve.
A/I : Yamada and Suzuki revise Earthquake stopper.

Again, according to N. Ohishi's master thesis, she used two metal plate (not 
comb like !) as electrode of actuator. Laser beam is in gap between two metal plates.
Actullay it makes sense because the 
bulk is large. The torelance of gap between electrode and bulk is modest.
-> Yamada and Suzuki consider details of actuator.

(e)Installation 
Misumi frame, lab jack (it can work with heavy load), and roters (they can work with
heavy load).

(5)Budget : Miyoki requests quoation for discussion.

Next meeting will be on the week of 18th of September. Kazuhiro will circulate doodle later.

A/I (all for Yamada and Suzuki)
(a)Asking Hirata-san details of wire breakers in Type B and Bp as reference later.
(b)Checking the size of breakers for wires in slits. 
(c)Revising or consideration about design of actuator and earthquake stopper.
(d)Quotation












(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.
 

試験するサファイアの質量はいくらになりますか？25kgですか？以下はm=25kgで仮定します。

- 耐久性に関してはtensil strengthで語るしかない（2次モーメントで考えたことはない）のですが、
  たしかに1kgをd=50umで吊っていたので、d=250umでいけるはずです。
  ただし、サファイアではないもので事前にテストした方が良いです。

- バイオリンモードの周波数は（計算をさぼって）検討書によると近似的にn pi wp sqrt(M/m)で、
  nはモード番号、wpは振り子周波数なので変わらず、基本的にsqrt(M/m)で決まるようですね。(テストマス質量M、ワイヤー質量m)
  つまり、バイオリン周波数は変化せず。

- d=100um tungstenだとすでに棒のようで、200umも棒でしたが、いずれも25kgのマスに対しては紐でしょう。

- これの意味するところは、tensil strength・振り子周波数・バイオリン周波数に対しては
  TAMAの場合と同じように振る舞うかも知れませんが、
  少なくともハンドリングに関しては急激にむずかしくなっていくと思います。
  つまり、ループに曲げることが大変むずかしくなると思います。

- ですので、2ループではなく4 wireで独立に吊ることになるのではないでしょうか。
  サファイアのサイドにクランプ機構をエポキシなりHCBなりで接着し、それに対してワイヤーを何らかの
  方法でクランプ（もしくはクランプ済のものを装着）するということになろうかと思います。
  （ループでできないわけではないと思いますが）


- 仮にループでやるにしても、伝統的なアルミのスタンドオフを使う川村法は振り子の揺れに合わせて
  スタンドオフが削れて熱雑音が増す(各種Qが低下)、というiLIGOでの知見があり、
  aLIGOでは金属ワイヤーの部分はサファイアプリズムでワイヤーのlaunching pointを決定するというようになっています。

- また、2ループでも4ワイヤーでも人力で上げ下げすると必要以上にtensil strengthが要求されるので、
  ゆっくりと上げ下げする機械的な機構が必要です。これはTAMAでもそうで、手で振り子をいじるとワイヤー切れやすいです。
  TAMAで50umがよく切れる、というのは栃久保さんの扱いが手荒だからで、最終的には既定の50umで全て吊りました。
  このためにはこの上げ下げ機構が重要でした。

- ワイヤーが切れたときにマスを支える「ケージ」は必要でしょう。
  これは上記の上げ下げ機構の機能を兼ねているといいのではないでしょうか。

- 4ワイヤーの構成ではまっすぐ荷重がかかるので、破断はtensil strengthで決まりやすいし、
  ワイヤーの事前テストも適当なおもりでできそうな気がするので、なにかと素性がいい気がします。