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Cryogenics in CLIO Masatake Ohashi and the LCGT collaboration

Cryogenics in CLIO Masatake Ohashi and the LCGT collaboration. What is CLIO ?. CLIO is a cryogenic interferometer with 100m baseline in the Kamioka Mine. CLIO is a prototype for LCGT. CLIO objective is to demonstrate reduction of thermal noise by mirror cooling.

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Cryogenics in CLIO Masatake Ohashi and the LCGT collaboration

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  1. Cryogenics in CLIOMasatake Ohashi and the LCGT collaboration 58th Fujihara Seminar 2009/05/28

  2. What is CLIO ? CLIO is a cryogenic interferometer with 100m baseline in the Kamioka Mine. CLIO is a prototype for LCGT. CLIO objective is to demonstrate reduction of thermal noise by mirror cooling. 58th Fujihara Seminar 2009/05/28

  3. Illustrated by Dr. Miyoki

  4. Contents CLIO Outline Sapphire Mirror Cryogenic Suspension System Cryostat and Cooling Technique Status of CLIO Present Status as a prototype of LCGT Summary 58th Fujihara Seminar 2009/05/28

  5. Sapphire Mirror 58th Fujihara Seminar 2009/05/28

  6. CLIO Sapphire Mirror Substrate: Crystal Systems (US) Polish: CANON (Japan) Coating: JAE (Japan) R=99.9% Diameter 100mm Thickness 60mm (same as TAMA mirrors) 58th Fujihara Seminar 2009/05/28

  7. Sapphire Mirror- Absorption - Absorption of laser light is important factor for mirror cooling. LCGT requirement : substrate 20ppm/cm (not achieved) coating 1ppm (OK) We need better quality sapphire substrates. 58th Fujihara Seminar 2009/05/28

  8. Sapphire Mirror- Mechanical Quality Factor - Measured by Dr. Uchiyama 300K 20K Suspended by double sapphire wires Over 108 is obtained at low temperature. 58th Fujihara Seminar 2009/05/28

  9. Sapphire Mirror- Dissipation of the Coating film - Measured by Dr. K. Yamamoto Loss Angle Temperature [K] Dissipation seems to be almost independent of Temperature 58th Fujihara Seminar 2009/05/28

  10. Cryogenic Techniques 58th Fujihara Seminar 2009/05/28

  11. Cryogenic Technique- Estimated Heat Generation in the Mirror - Mirror substrate : Sapphire Suspension rods : Sapphire Safety factor ・ Design q=290 mW T=20 K Exhaust heat 58th Fujihara Seminar 2009/05/28

  12. CLIO Cryostat for end mirror 58th Fujihara Seminar 2009/05/28

  13. Low vibration Pulse Tube refrigeratordeveloped by KEK and SUMITOMO 58th Fujihara Seminar 2009/05/28

  14. Cooling test and achieved temperature Several days are necessary for mirror cooling. 63K Measured by Dr. Uchiyama 8.8K 12.9K 45K 58th Fujihara Seminar 2009/05/28

  15. 300K Radiation in vacuum pipes 300K Radiation from inside of vacuum pipes warms mirrors Serious Problem for cooling Mirror (20K) Radiation shield (40K) 300K Radiation ( straying ) Radiation shield, Baffles, … 58th Fujihara Seminar 2009/05/28

  16. Radiation Shields (cloistered mirror) Radiation shield for mirrors 58th Fujihara Seminar 2009/05/28

  17. Cryogenic suspension system Basic design is double pendulum Intermediate mass Mirror 58th Fujihara Seminar 2009/05/28

  18. Cooling method by a cryocooler 58th Fujihara Seminar 2009/05/28

  19. Cooling procedure STEP3 cooling mirror alignment STEP1 cooling mirror alignment STEP4 cooling mirror alignment STEP2 cooling mirror alignment Cooling shortens length of suspension by 2mm 58th Fujihara Seminar 2009/05/28

  20. Current status of CLIO 58th Fujihara Seminar 2009/05/28

  21. Noise budget at room temperature Thermal noise of suspension Thermal noise of mirror Current sensitivity is limited by thermal noises 58th Fujihara Seminar 2009/05/28

  22. Expected Noise Spectrum at 20K This curve is already realized We started mirror cooling last week. 58th Fujihara Seminar 2009/05/28

  23. Today’s DATA One mirror is cooled to 14K. Preliminary 58th Fujihara Seminar 2009/05/28

  24. SUMMARY Cryogenic prototype CLIO is in commissioning phase. Cryogenic interferometer is feasible. But we have to improve some points, especially, the combination of heat transfer and vibration isolation is important. 58th Fujihara Seminar 2009/05/28

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