Current status of sapphire fibers Kazuhiro Yamamoto Institute for Cosmic Ray Research The university of Tokyo I will explain cryogenic payload in 10 minutes. LCGT cryogenic payload meeting 30 November 2011

Introduction Sapphire fibers with thick end Bonding Ears on mirror OK, what is cryogenic payload ? This is the cross section of tunnel of LCGT. This tall tower is vibration isolation system. There is cryogenic payload under this vibration isolation. Cryogenic payload is in cryostat. Payload includes mirror, which is the most important part of gravitational wave detector.

Sapphire fiber This is the schematic view of payload. It is surrounded by radiation shield. This is the triple pendulum. At that bottom, you can find mirror, this red circle. Here are heat links made from aluminum to cool cryogenic paylaod.

Sapphire fibers Test sample (T. Uchiyama) Cryogenic payload is an essential part of cryogenic interferometer. This includes main mirror ! However, it is on the border line between vibration isolation and cryogenic sub-groups. As Kentaro mentioned yesterday, some problems happens on or around border. So, I am assigned to manage the development of cryogenic payload.

Sapphire fibers Three companies : Moltech, Kyocera, Namiki Moltech : Uchiyama has already ordered. They can not polish fibers. Kyocera and Namiki can polish. What is our plan in long term ? The first step is prototype cryostat and payload. They will be constructed by March 2013 in this Kashiwa campus. Main target is test of cooling. We check whether mirror could be cooled enough. However, almost all fundamental items should be checked using this prototype. After we check it carefully, the test in LCGT cryostat in Kamioka mine will be started.

Sapphire fibers Kyocera : They can make fiber with thick end but discussion is in progress. (Meeting : 1st of December) Kyocera can polish fiber (even if we provide). The discussion is necessary before the polish. There are unpolished straight fibers in KEK. If they are polished, we will check properties. Budget of prototype of cryostat and payload is a part of Leading Edge Research Program. But we must make effort to obtain more budget. Of course, any supports are welcomed. I would like to mention that cryogenic payload is one of the key issues of international collaboration as Kuroda sensei showed yesterday. For example, IRSES program to exchange researcher in Europe is accepted. Cryogenic payload is one of main items in this program. Moreover, the other proposal for cryogenic payload is in progress in U.S.A.

Sapphire fibers Namiki : They can make fiber with thick end and polish fibers (even if we provide). Yamamoto asked details but there is no reply up to now.

Bonding 常温接合：並木にサンプル製造、研磨を 依頼するつもりだったが、流れる 研磨を岡本光学に問合わせ中 （鈴木） 　　　　　　　依頼するつもりだったが、流れる 　　　　　　　研磨を岡本光学に問合わせ中 　　　　　　　　　　　　　　　　　　　　　　　（鈴木） メタライズ接合：京セラと協議中 　　　　　　　　　　他社にも問合わせ中（鈴木）　　　　

Ears on mirror 一体加工（切り出し）はどうか？ 図面を書いて問い合わせる予定（山元） 並木と京セラ　　　　

Cryogenic payload parameters

山元がparameterを まとめました http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=570 http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=569

マス（鏡以外）：とりあえず銅 熱伝導低くても問題なし ワイヤ：タングステン（リコイルマス（４本）、 中間マスのリコイルマス（３本））と マレージング（中間マス（１本）） 常温部からのワイヤはとりあえず ボルファ（１本）

中間マスのリコイルマス： 上から見てロの字から光軸方向からみて ロの字（重心を合わせるため） プラットフォーム：とりあえずクライオスタット の中。60kgから120kgに。 基本的にワイヤは重心と同じ高さでつかむ がその機構はまだ考えていない。

ヒートリンクはまだ決めてない。 形状を変えざる得ない（半円弧から U字もしくは楕円状） 麻生君に計算依頼

今後の予定 Riccardo提案（プラットフォーム外に）の検討 組み立て方 モーター、アクチュエータ、センサなど