1. 1 Kazuhiro Yamamoto Institute for Cosmic Ray Research (ICRR) the University of Tokyo KAGRA face to face meeting Institute for Cosmic Ray Research, Kashiwa, Japan 15 February 2013 Report from sub-groups Cryogenic Cryogenic payload

2. 2 Contribution R. Takahashi, T. Sekiguchi, Y. Sakakibara, C. Tokoku, M. Kamiizumi, U. Iwasaki, E. Hirose, T. Uchiyama, S. Miyoki, M. Ohashi, K. Kuroda, T. Akutsu A, H. Ishizaki A, T. Suzuki B, N. Kimura B, S. Koike B, T. Kume B, K. Tsubono C, Y. Aso C, T. Ushiba C, K. Shibata C, D. Chen D, N. Ohmae E, K. Somiya F, R. DeSalvo G, E. Majorana H, L. Naticchioni H, W. Johnson I, A. Cumming J, R. Douglas J, K. Haughian J, I. Martin J, P. Murray J, S. Rowan J, G. Hofmann K, C. Schwarz K, D. Heinert K, R. Nawrodt K, S. Goto L, KAGRA collaboration ICRR.UT, NAOJ A, KEK B, Phys.S.UT C, Astro.S.UT D, E.UT E,S.TIT F, Sannio Univ. G, INFN H, Louisiana State Univ. I, University of Glasgow J, Friedrich-Schiller-Universitaet Jena K, Jecc Torisha L, KAGRA collaboration

3. 3 0. Abstract Although there are many topics, but here, I will explain (1)1/4 cryostat (2)Experiments in Toshiba cooling test (3)Sapphire fibers

4. 4 Contents 1.Introduction 2.1/4 cryostat 3.Experiments in Toshiba cooling test 4.Sapphire fibers 5.Summary

5. 55 1. Introduction 555 3km Mozumi Y-end Sakonishi X-end Atotsu Center Vibration isolation system, Cryocooler unit, Cryostat, Cryogenic payload Schematic view of KAGRA interferometer Four mirrors of arm cavity will be cooled. Kamioka mine (Underground site)

6. 66 Cryogenic mirror Cryostat Vibration Isolation Outline of vibration isolation and cryostat 1. Introduction 14 m

7. 7 to SAS View ports Remote valve unit 4 Low vibration cryocooler unit Main LASER beam Cryostat Stainless steel t20mm Diameter 2.6m Height ~3.6m M ~ 10 ton Cryo-coolers Pulse tube, 60Hz 0.9 W at 4K (2nd) 36 W at 50K (1st) Outline of cryostat Cryogenic payload Mirror 1. Introduction S. Koike

8. 888 Outline of cryogenic payload Sapphire fiber Sapphire mirror (About 20K) Inner shield (8K) 1. Introduction Y. Sakakibara et al., Classical and Quantum Gravity 29 (2012) 205019. Outer shield (80K) Heat links (pure Al) Vacuum chamber (300K)

9. 9 Cryogenic payload is not a simple system. We need cryostat to test cryogenic payload performance. KAGRA cryostat is not appropriate for test. (1)Difficult access in mine (2)Cleanness must be kept 1/4 cryostat will be prepared in Kashiwa campus. 1/4 means number of cryocooler, not size. 2. 1/4 cryostat

10. 10 2. 1/4 cryostat Bid (for parts of 1/4 cryostat) was opened ! (Jecc Torisha) Discussion for final design is in progress. Preliminary and not latest version.

11. KAGRA cryostat is being assembled ! at Toshiba Keihin Product Operations 11 3. Experiments in Toshiba cooling test

12. Cooling test of KAGRA cryostat is in progress. 12 We have plans of experiments in Toshiba cooling test of KAGRA cryostat. Experiment 1 : Initial cooling time Sample 1 : Metal hollow spheres Sample 2 : Dummy payload Experiment 2 : Measurement of shield vibration Accelerometers developed by Luca Naticchioni (Rome) and Dan Chen (ICRR) 3. Experiments in Toshiba cooling test

13. 13 At beginning of initial cooling, heat transfer is dominated by radiation. Initial cooling time of KAGRA cryostat and cryogenic payload is about 2 months (if no tricks). Diamond Like Carbon (DLC) coating (High emissivity, Large radiation) on shields and payload (except for mirror) Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

14. 14 Initial cooling time with DLC (shield and mass) Calculation by Y. Sakakibara Almost half ! Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

15. 15 Experiment 1 : Initial cooling time Experimental test of effect of high emissivity coating (DLC) Inner sphere (copper) is suspended inside outer sphere (aluminum) at 77 K Cooling time is examined with and without DLC coating 3. Experiments in Toshiba cooling test

16. 16 Experiment 1 : Initial cooling time We can observe DLC effect. 3. Experiments in Toshiba cooling test

17. 17 Sample 1 : Metal hollow spheres (100 mm in diameter) to check scaling law Y. Sakakibara’s small experiment: 30 mm in diameter Both spheres were suspended in the shields. The sphere without DLC is being cooled now ! Without DLC With DLC Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

18. 18 The sphere without DLC is being cooled now ! Latest result Experiment 1 : Initial cooling time Calculation of Yusuke is quite correct ! Sample 1 : Metal hollow spheres 3. Experiments in Toshiba cooling test

19. 19 Sample 2 : Dummy payload (hollow masses) Half size Hollow masses (~5 kg) DLC coating Sapphire bulk as dummy mirror Preparation is in progress. S. Koike (100 mm in diameter) Evaluation of emissivity Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

20. 20 Experiment 1 : Initial cooling time We assembled before the cleaning and DLC coating deposition ! Sample 2 : Dummy payload 3. Experiments in Toshiba cooling test

21. 21 Experiment 1 : Initial cooling time Sample 2 : Dummy payload 21 We assembled before the cleaning and DLC coating deposition ! Cleaning and DLC coating deposition is in progress. They will arrive at ICRR on 20th of February. 3. Experiments in Toshiba cooling test

22. 22 Experiment 1 : Initial cooling time Sample 2 : Dummy payload 22 Yusuke calculated the cooling time of 1/2 dummy payload. 3. Experiments in Toshiba cooling test

23. 23 Vibration of shield could be problems. Vibration via heat links, Scattered light We must measure the vibration of shield. This measurement is at cryogenic temperature and in vacuum. Luca Naticchioni (Rome) and Dan Chen (ICRR) will measure vertical and horizontal vibration of radiation shield of KAGRA in cooling test of Toshiba, respectively. ELiTES supports Luca’s visit. Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

24. 24 Dan Chen’s accelerometer His accelerometer is consistent with commercial one (in air). Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

25. 25 Dan Chen’s accelerometer He is proceeding with cryogenic test before measurement in Toshiba. Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

26. 26 Luca Naticchioni’s accelerometer Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

27. 27 Experiment 2 : Measurement of shield vibration Luca’s accelerometer was installed in the shield (13 th of Feb). 3. Experiments in Toshiba cooling test

28. 28 Luca’s accelerometer was installed (13 th of Feb). Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

29. 29 Luca’s accelerometer was installed (13 th of Feb). Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

30. 30 4. Sapphire fibers 30 Test sample (T. Uchiyama) Sapphire fibers with nail heads are necessary to suspend mirrors.

31. 31 Length = 350 mm diameter = 1.8 mm Almost as needed in bKAGRA. Need to check the quality and improvement. T. Uchiyama asked MolTech GmbH (Germany). Sapphire fibers have already come ! 4. Sapphire fibers

32. 32 Ettore Majorana asked IMPEX HighTech GmbH (German company). They made similar fibers (nail heads on the both ends). 4. Sapphire fibers

33. 33 Quality check Q-value and profile of Moltech fibers: Y. Sakakibara at Glasgow and Jena. His stay is stimulated by ELiTES. Thermal conductivity measurement of Moltech fibers in Jena Discussion for strength test with Glasgow 4. Sapphire fibers

34. 34 Profile measurement in Glasgow 4. Sapphire fibers

35. 35 Q measurement in Jena (cool) and Glasgow (300K) It is comparable with KAGRA requirement ! Preliminary result 4. Sapphire fibers

36. 36 After Yusuke left …. It is comparable with KAGRA requirement ! Q measurement in Jena Preliminary result 4. Sapphire fibers

37. 37 After Yusuke left …. It is same as KAGRA requirement (size effect) Thermal conductivity measurement in Jena Preliminary result 4. Sapphire fibers

38. 38 After Yusuke left …. It is smaller than KAGRA requirement, but same order of magnitude. Thermal conductivity measurement in Jena Preliminary result 4. Sapphire fibers

39. 39 After Yusuke left …. Clamp for IMPEX fibers in Jena 4. Sapphire fibers

40. 40 Strength test Kick off meeting with Glasgow (23 rd Jan) (Thanks for E. Hirose) http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=1494 Glasgow group has (1)apparatus for tensile, bending, shear tests. (2)very high motivation. Kazuhiro should summarize strength requirement (He wrote memo, but it should be revised). 4. Sapphire fibers

41. 41 Next plan Measurement in Jena and Rome Discussion for strength test with Glasgow We are discussing other plan within ELiTES framework. 4. Sapphire fibers

42. 42 5. Summary 1/4 cryostat : Bid for parts was opened and discussion for final design is in progress. Experiments in Toshiba cooling test : Initial cooling time Metal sphere with and without DLC Both of them are installed in shield. Result without DLC is same as our expectation (up to now). 1/2 dummy payload Preparation is in progress. Measurement of shield vibration Intallation and preparation are in progress.

43. 43 5. Summary Sapphire fibers Moltech and IMPEX provided fibers with nail heads. Measurement of Q-values and thermal conductivity : Result is preliminary, but promising. Discussion for strength test was started. ELiTES strongly supports and stimulates research for KAGRA cryogenic payload.

44. 44 Thank you for your attention !

45. 45 Some items for future research (not perfect list) (a)Investigation material properties (Q, thermal conductivity, strength etc.) of coating, fiber and so on. (b)Sapphire bonding, Sapphire fiber clamp (c)Control and damping scheme Actuators and sensors at cryogenic temperature (d) Mechanical and thermal simulation for payload (e) Vertical spring in cryostat (f) Reduction of initial cooling time Thermal resistance of clamp.... (g) Baffles for scattered light in radiation shield (h) Assembly procedure 7. For future

46. 46 8. Summary Cryostat : Assembly is in progress. Cooling test is coming soon. Cryogenic duct : Optimum position of 5 buffles Future work : scattered light Cryocooler unit : Cooling test and vibration measurement : OK Cryogenic payload Preparation for 1/4 cryostat to check payload performance is in progress. Current main R&D topics Inital cooling time, Sapphire fiber with nail head, Coating mechanical loss, Vibration of shield

47. 47 8. Summary ELiTES has already started and supports the development of KAGRA cryogenic system. If you want to join our mission, let us know.

48. 48 2. Issues (1)How to assemble Details of construction, clean room …. (2)Strength Tensile strength, development of clamp, sapphire bonding … (3)Control and damping system to reduce fluctuation and instability Actuators (what and where), resonant mode (frequency and Q) and so on

49. 49 2. Issues (4)Cooling Temperature of mirror (below 20 K), initial cooling time, heat resistance of clamp … (5)Noise Thermal noise, vibration via vibration isolation system and heat links …