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

2. 2 Contribution R. Takahashi, K. Ono, T. Sekiguchi, Y. Sakakibara, C. Tokoku, M. Kamiizumi, U. Iwasaki, E. Hirose, A. Khalaidovski, T. Uchiyama, S. Miyoki, M. Ohashi, K. Kuroda, T. Akutsu A, H. Ishizaki A, F. E. Peña Arellano 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, M. Tanaka L, S. Ioka M, K. Nakamoto M, H. Nezuka M, 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, Toshiba Keihin Product Operations M, KAGRA collaboration

3. 3 0. Abstract Although there are many topics, but here, I will explain (1)KAGRA cryostat (2)Cryoduct (2)1/4 cryostat (3)Monolithic sapphire suspension

4. 4 Contents 1.Introduction 2.KAGRA cryostat 3.Cryoduct 4.1/4 cryostat 5.Sapphire suspension 6.Human resources 7.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. 88 Outline of vibration isolation and cryostat 88888 2 Pulse tube cryocoolers Pulse tube cryocoolers Baffles Cryoduct Outer shield (80K) Inner shield (8K) Vacuum chamber (300K)

9. Outline of vibration isolation and cryostat 99999 Pulse tube cryocoolers Heat link (pure Al) Sapphire mirror (About 20K) Heat link (pure Al) Sapphire fiber

10. 10 Main topics Experiment using KAGRA cryostat Toshiba assembled four cryostats. Cryoduct Redution of 300K radiation propagation 1/4 cryostat Performance test of cryogenic payload Sapphire monolithic suspension Key component of KAGRA 1. Introduction

11. KAGRA cryostats have already been assembled ! at Toshiba Keihin Product Operations 11 2. KAGRA cryostat

12. Cooling test for all four KAGRA cryostats January 2013 – April 2013 Three of them were move to a warehouse near Kamioka on the 27 th and 28 th of July. Cooling test for the 3rd cryostat July 2013 – August 2013 12 2. KAGRA cryostat

13. Three cryostats were move to a warehouse near Kamioka on the 27 th and 28 th of July. 13 2. KAGRA cryostat

14. Three of cryostats were move to a warehouse near Kamioka on the 27 th and 28 th of July. 14 2. KAGRA cryostat

15. Three of cryostats were move to a warehouse near Kamioka on the 27 th and 28 th of July. 15 2. KAGRA cryostat

16. 16 Cooling test of KAGRA cryostat in Toshiba 16 Test 1 : Initial cooling time of ratidation shield How long does it take to cool shield ? Test 2 : Heat load test How much is temperature with extra heat load? C. Tokoku et al., Proceedings of CEC/ICMC 2013 (2EPoE1-03) K. Yamamoto et al., Opening a new era for the astrophysics: The future detectors of gravitational waves (19 April 2013) http://gwdoc.icrr.u-tokyo.ac.jp/cgi- bin/DocDB/ShowDocument?docid=1615 2. KAGRA cryostat

17. 17 Test 1 : Initial cooling time The result (2 weeks) is similar to our expectation. There is no large unexpected heat invasion and resistance. 2. KAGRA cryostat Cooling test of KAGRA cryostat in Toshiba

18. 18 Experiments in cooling test of KAGRA cryostat Experiment 1 : Initial cooling time of cryogenic payload This initial cooling time should be short. Yusuke Sakakibara will explain details later. Experiment 2 : Measurement of shield vibration This vibration causes motion of mirrors and scattered light noise. Dan Chen will explain details later. 2. KAGRA cryostat

19. 19 Two items for cryoduct (1)300K radiation though this cryo duct must be small. (2)Scattered light noise by this duct should be small. Not only scattered light itself but also vibration of cryo duct should be small. Preparation for experiment is in progress. Yusuke Sakakibara will explain details later. 3. Cryoduct

20. 20 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. It will be delivered on the end of September. 4. 1/4 cryostat

21. 21 Construction is in progress (Jecc Torisha). Vacuum chamber : 1.2 m in diameter, 1.6 m in height 4. 1/4 cryostat

22. 22 Construction is in progress (Jecc Torisha). Radiation shield

23. 23 Construction is in progress (Jecc Torisha). Support frame inside radiation shield

24. 24 5. Sapphire suspension 24 Sapphire monolithic suspension Sapphire mirror suspended by sapphire fibers. Key component of KAGRA We need (a)Drilled sapphire mirror (b)Sapphire fibers with nail heads (c)Bonding between bulk and fibers

25. 25 5. Sapphire suspension 25 Drilled sapphire bulk We ordered Shinkosha (test sample). It will be delivered on the 16 th of August. KAGRA mirrors : 220 mm in diameter

26. 26 5. Sapphire suspension 26 Drilled sapphire bulk We ordered Shinkosha (test sample). It will be delivered on the 16 th of August.

27. 27 5. Sapphire suspension 27 Test sample (T. Uchiyama) Sapphire fibers with nail heads are necessary to suspend mirrors.

28. 28 MolTech GmbH (Germany) and IMPEX HighTech GmbH (Germany) have already delivered ! 5. Sapphire suspension Sapphire fibers with nail heads Although the size is similar to that of KAGRA, quality check is necessary.

29. 5. Sapphire suspension 29 Sapphire fibers with nail heads Quality check under collaboration with ET (ELiTES) Q-value Measurement in Glasgow, Jena, and Tokyo Plan for measurement in Rome Thermal conductivity Measurement in Jena, Rome and Tokyo Strength Measurement preparation in Glasgow

30. 30 Latest summary 5. Sapphire suspension Moltech IMPEX KAGRA requirement Q-value 10 7 2*10 6 5*10 6 at 20K Thermal Conductivity 3000 5000 5000 at 20K [W/m/K] -10000 Although these results are promising, further investigation is necessary. Sapphire fibers with nail heads

31. 31 5. Sapphire suspension 31 Bonding between sapphire fibers and sapphire mirror Investigation of Hydroxide Catalysis Bonding is in progress in Glasgow. (Rebecca Douglas, GWADW2013). Strength (about 60 MPa) measured by her is 10 times larger than those of previous papers. T. Suzuki et al., Journal of Physics; Conference Series 32(2006)309. A. Dari et al., Classical and Quantum Gravity 27(2010)045010. Plan : Measurement of thermal resistance and so on.

32. 32 5. Sapphire suspension 32 Assembled sapphire monolithic suspension Performance of assembled monolithic sapphire pendulum must be checked. Before that, sapphire bulk is suspended by sapphire fibers using indium as thermal and mechanical contact (some kinds of “glue” instead of bonding) between sapphire bulk and fibers. We will investigate performance and obtain expertise for the monolithic pendulum test as first step.

33. 33 5. Sapphire suspension 33 Assembled sapphire monolithic suspension A. Khalaidovski is designing the frame for this first step.

34. 34 6. Human resources 34 Fresh persons Dr. Aleksandr Khalaidovski from Hannover, June 2013-May 2014 Sapphire monolithic suspension (Dr. Fabián Erasmo Peña Arellano from Birmingham, May 2013 – April 2016 Cryogenic sensor) Dr. Rahul Kumar from Glasgow, October 2013 – September 2014 Simulation and development of payload

35. 35 6. Human resources 35 ELiTES: ET-LCGT interferometric Telescope Exchange of Scientists Grant for collaboration about cryogenic between KAGRA and ET European 7th Framework Programme Marie Curie action (Mar. 2012 - Feb. 2016) European people can visit Japan for KAGRA.

36. 36 6. Human resources 36 Visitors supported by ELiTES in the last half year Christian Schwarz, Gerd Hofmann, Ronny Nawrodt (Jena) Automatic systems to measure Q-values and thermal conductivity of sapphire fibers Luca Naticchioni, Maurizio Perci, Ettore Majorana (Rome) Measurement of KAGRA radiation shield at cryogenic temperature (Kieran Craig (Glasgow) Measurement of coating mechanical dissipation)

37. 37 6. Human resources 37 Japanese graduate students visited (or will visit) Europe. Yusuke Sakakibara (October 2012 – December 2012) Investigation for coating and sapphire fibers (Glasgow and Jena) ET meeting, Hannover, December 2012 http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=1420 http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=1469 (Takanori Sekiguchi (January 2013 – March 2013) Investigation for vibration isolation (Amsterdam) http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=1708 ) Dan Chen (September 2013 – October 2013) Investigation for sapphire fiber (Rome)

38. 38 7. Summary KAGRA cryostat Three cryostats were transported to Kamika. Test for KAGRA cryostat temselves Experiment : Initial cooling time of payload Radiation shield vibration Yusuke Sakakibara and Dan Chen will explain details later. Cryoduct Preparation for experment Yusuke Sakakibara will explain details later. 1/4 cryostat to check cryogenic payload will be delivered by the end of September.

39. 39 7. Summary Sapphire monolithic suspension Drilled bulk will be delivered on 16th of August. Experiments for sapphire fiber and sapphire bonding are in progress but the results are promising. We are preparing the first step experiment of monolithic sapphire suspension. Human resources Brilliant fresh persons Strong support from ELiTES Young Japanese researchers visit Europe.

40. 40 Thank you for your attention !

41. 41 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

42. 42 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

43. 43 8. Summary ELiTES has already started and supports the development of KAGRA cryogenic system. If you want to join our mission, let us know.

44. 44 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

45. 45 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 …

46. 46 Test 2 : Heat load test How much is temperature with extra heat load ? We can derive extra heat load from temperature. Examples for extra heat load Scattered light by mirror Heat absorption in mirror 300 K radiation through holes for main beam 46 Cooling test in Toshiba

47. 47 Cooling test in Toshiba 47 Test 2 : Heat load test 47 Pulse tube cryocoolers Heater and thermometer Sapphire mirror

48. Cooling test in Toshiba 48 Test 2 : Heat load test 48 2 W 5 W 10 W 0 W Scatted power is 5 W when scattered loss on the mirror surface is 10 ppm.

49. Cooling test in Toshiba 49 Test 2 : Heat load test 49 Pulse tube cryocoolers Heater and thermometer Sapphire mirror

50. Cooling test in Toshiba 50 Test 2 : Heat load test 50 4 W 10 W 0 W According to our design, temperature should be below 8 K when heat absorption in mirror is 1 W.

51. 51 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.

52. 52 After Yusuke left …. Clamp for IMPEX fibers in Jena 4. Sapphire fibers

53. 53 Profile measurement in Glasgow 4. Sapphire fibers

54. 54 Q measurement in Jena 5. Sapphire suspension Sapphire fibers with nail heads

55. 55 Thermal conductivity measurement in Jena 5. Sapphire suspension Sapphire fibers with nail heads

56. 56 Latest summary 5. Sapphire suspension Crystal axis Ribbon ? Sapphire fibers with nail heads