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Kazuhiro Yamamoto

Institute for Cosmic Ray ResearchThe university of Tokyo

Current status

KAGRA(LCGT) cryogenic payload meeting8 February 2012

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There are a lot of meetings in the recent one month ...

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AOS meeting(13th of Jan.)T. Akutsu pointed out that (a)the baffles for scattered light might be installed in cryostat. Where are they put ? How are they suspend for vibration isolation ? How the heat by the light absorption is extracted ?(b)there is the possibility that duct shield might be the problem of the scattered light.

We discussed, but it is not so easy to find the solutions …

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AOS meeting(13th of Jan.)Homework(a)Rough evaluation of the noise by scattered light (Akutsu)(b)Temperature of inner shield with 4 W heat load (Kimura) The answer is 12.3 K.(c) Magnitude of large angle scattered light measured in LIGO The answer is 10 ppm (H. Yamamoto).(d) Simulation of vibration of shield (Tokoku)

Discussion with Mike Smith : Today, after this meeting

Next meeting : 15th of Feb. (Wed) 10:30- ICRR, TV conference room EVO (LCGT AOS CRYOGENIC PAYLOAD)

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Internal review(30th of Jan.)Slideshttp://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=810

Action items(a)Revision(b)Investigation of the light scattered by the edge of baffles in duct shield(c)Quality check plan for sapphire fibers(d)Vibration of radiation shields (scattered light)

Items for main interferometer : Calculation for hierarchy control

Deadline of document of external review : 17th of MarchExternal review : 17th-20th of April

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f2f meeting(2nd-4th of Feb.)Reoprt of sub groups : 3rd of Feb.http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=849

Warren Johnson and Riccardo DeSalvo join cryogenic payload mailing list.

New KAGRA collaborator SICCAS‐GCL Crystal Research & Development Centerhttp://gwdoc.icrr.u-tokyo.ac.jp/cgibin/DocDB/ShowDocument?docid=820

They can process (cut and so on) sapphire bulk.K. Yamamoto will discuss this issue with Lihe Zheng and Jingya Wang in this week.

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f2f meeting(2nd-4th of Feb.)Prof. Mio : a-axis sapphire (25cm in diameter, 15cm in thickness) will arrive soon. It can be used as mirror for 1/4 cryostat experiment.