1. 1 Kazuhiro Yamamoto Institute for Cosmic Ray Research (ICRR) the University of Tokyo KAGRA face to face meeting Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa, Chiba, Japan 14 February 2014 Cryo-payload Suspension structure

2. 2 Contribution R. Takahashi, K. Ono, T. Sekiguchi, Y. Sakakibara, C. Tokoku, M. Kamiizumi, U. Iwasaki, E. Hirose, A. Khalaidovski, R. Kumar, 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, G. Hammond 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, here, I will explain (1)Schedule (2)Overall design (3)Monolithic sapphire suspension (4)Heat links

4. 4 Contents 1.Introduction 2.Schedule 3.Overall design 4.Sapphire suspension 5.Heat links 6.ELiTES activity 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 Outline of vibration isolation and cryostat 1. Introduction 14 m

7. 77 Cryogenic mirror Cryostat Vibration Isolation Outline of vibration isolation and cryostat 1. Introduction 14 m

8. 8 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

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 1. Introduction Schematic view of cryogenic payload http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2106 Platform Intermediate Recoil Mass Intermediate Mass Test Mass (sapphire mirror)

11. Design is in progress. Details should be changed. 11 1. Introduction Outline of cryogenic payload http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2106 Intermediate Mass Intermediate Recoil Mass Test Mass (sapphire mirror)

12. 12 1. Introduction Outline of cryogenic payload in radiation shield http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2106

13. 13 1. Introduction “Sapphire monolithic suspension” One of the most important parts of KAGRA : Main sapphire mirrors are included. All parts are made from sapphire. Details should be changed. Mirror

14. 14 2. Schedule End of 2017 : Cryogenic interferometer operation This is the significant milestone of KAGRA. Delivery of cryogenic payload By March 2015, One payload By March 2016, Three payloads “Official plan” For sapphire monolithic suspension, so aggressive ! The suspensions will be improved step by step. Initial phase suspension before final phase one is necessary.

15. 15 2. Schedule “Initial phase” Larger thermal noise but more feasible First cryogenic payload (2014) is a “Initial phase”. R&D for final phase should be in progress at the same time. Otherwise, thermal noise can not be reduced. We must do our best for three payloads as final phase (2015).

16. 16 2. Schedule 16 Although thermal noise is large, it should be cooled (heat load test is necessary). It should be as simple as possible (budget and human resources). It can be replaced by final phase sapphire monolithic suspension later. “Initial phase”

17. 17 2. Schedule 17 (1)No bonding, but screws, indium, cradle (2)Thick tungsten wires (they transfer heat) There are some ideas for “Initial phase” Indium Any “Initial phase” plans have open issues. R&D must be finished by May 2014.

18. 18 3. Overall design 18 Not sapphire suspension, but cryogenic payload in total Takanori Sekiguchi and Eiichi Hirose visited Stanford (December 2013) to discuss overall design with control system. Design and discussion are in progress. Preliminary design document http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2106

19. 19 3. Overall design 19 E. Hirose organizes team to design the first cryogenic payload (Member : E. Hirose, T. Sekiguchi, R.Takahashi, R. Kumar). Dead line is June 2014. Short meeting every morning Some figures in 1. Introduction are brought by this team.

20. 20 4. Sapphire suspension 20 Sapphire monolithic suspension R&D for components are in progress. There are a lot of items. Here, (1)Sapphire fiber (2)Sapphire blade spring (3)Sapphire bonding are introduced.

21. 21 Test sample (T. Uchiyama) Sapphire fibers with nail heads are necessary to suspend mirrors. 4. Sapphire suspension

22. 22 MolTech GmbH (Germany) and IMPEX HighTech GmbH (Germany) have already delivered ! Sapphire fibers with nail heads 4. Sapphire suspension MolTech GmbH IMPEX HighTech GmbH

23. 23 Sapphire fibers with nail heads Quality check under collaboration with ET (ELiTES) Q-value Measurement in Glasgow, Jena, Rome and Tokyo Thermal conductivity Measurement in Jena, Rome and Tokyo Strength Measurement in Glasgow 4. Sapphire suspension

24. 24 Latest summary of Q and thermal conductivity Moltech IMPEX KAGRA requirement Q-value 10 7 1*10 6 5*10 6 at 20K -6*10 6 Thermal Conductivity 3000 5000 5000 at 20K [W/m/K] -6000 Sapphire fibers with nail heads IMPEX fibers satisfy the KAGRA requirement. 4. Sapphire suspension

25. 25 Q of IMPEX fiber (D. Chen) Sapphire fibers with nail heads 4. Sapphire suspension Requirement : 5*10 6 https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7

26. 26 Thermal conductivity of IMPEX fiber Sapphire fibers with nail heads 4. Sapphire suspension arXiv: 1401.2346

27. 27 Paper about thermal conductivity measurement was submitted to Classical and Quantum Gravity. Sapphire fibers with nail heads arXiv: 1401.2346 4. Sapphire suspension

28. 28 Strength test in Glasgow Fiber suspended weight. Moreover, weight was swung or pulled. Sapphire fibers with nail heads 15kg test hang Broken jointed end 4. Sapphire suspension

29. 29 Strength test in Glasgow Fiber suspend weight. Moreover, weight was swung or pulled. G. Hammond reported in ELiTES meeting (December 2013). https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 Safety factor derived from measurement : 3 - 16 Sapphire fibers with nail heads Broken jointed end 4. Sapphire suspension E. Majorana will visit Glasgow in this month and try strength test.

30. 30 Although we investigated fibers with round nail heads … Flat surfaces are necessary for bonding. New fibers with square nail head (IMPEX) is coming soon (end of February) ! Sapphire fibers with nail heads Our plan for these fibers Surface flatness check (less than /10 ( =630nm)) Measurement of thermal conductivity and Q 4. Sapphire suspension

31. 31 Sapphire fibers are thick (1.6 mm in diameter) for heat transfer. Stretch by sapphire mirror weight (23kg) : 21  m If difference between length of 4 fibers are larger than 21  m, there is no tension in one fiber ! Blade spring is necessary. Sapphire blade spring 4. Sapphire suspension

32. 32 Sapphire blade spring (design is in progress) 4. Sapphire suspension Vertical resonant frequency : 17.4 Hz Max. stress : 159 MPa Bending breaking stress :300 MPa (G. Hammond reported in ELiTES meeting https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 ) R. Kumar 46 mm 90 mm

33. 33 Bonding between sapphire fibers and sapphire mirror Hydroxide Catalysis Bonding (AdLIGO and Virgo) If fibers are broken, bonding parts must be taken apart … Candidates : Indium, Optical contact, Screws Test (in progress or near future plan) Strength test (tensile and shear) : KEK Thermal resistance : ICRR Mechanical dissipation : Jena and Glasgow (ELiTES) 4. Sapphire suspension

34. 34 Bonding between sapphire fibers and sapphire mirror Hydroxide Catalysis Bonding 4. Sapphire suspension https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 Rebecca reported in ELiTES meeting (Dec. 2013).

35. 35 Bonding between sapphire fibers and sapphire mirror Hydroxide Catalysis Bonding (Rebecca Douglas[Glasgow], 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. Rebecca Douglas and Karen Haughian stayed in Japan in the last autumn. Rebecca reported in ELiTES meeting (Dec. 2013). https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 4. Sapphire suspension

36. 36 Rebecca Douglas and Karen Haughian HCB Shear strength test (Strength vs crystal direction) Preliminary https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 4. Sapphire suspension

37. 37 Next HCB shear strength test is in progress. https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7 4. Sapphire suspension

38. 38 Indium If fibers are broken, bonding parts must be taken apart … Indium is one of candidates. Hot welding Foil or evaporation (thickness: <20  m) are prepared and heat is applied. When bonding parts are taken apart, heat and acid are applied. 4. Sapphire suspension

39. 39 We are preparing sample (KEK) … 4. Sapphire suspension

40. 40 We are preparing sample (KEK) … 4. Sapphire suspension

41. 41 We are preparing sample (KEK) … 4. Sapphire suspension

42. 42 We are preparing sample (KEK) … 4. Sapphire suspension

43. 43 We are preparing sample (KEK) … 4. Sapphire suspension

44. 44 R&D for integration of components One fiber prototype Full prototype 4. Sapphire suspension

45. Outline of vibration isolation and cryostat 45 Pulse tube cryocoolers Heat link (pure Al) 5. Heat links

46. 46 5. Heat links 46 Heat links must be thick and short as heat path. However they must be thin and long as vibration path ! Dan Chen reports vibration via heat link in the next talk. Yusuke Sakakibara explains initial cooling time of cryogenic payload at the first talk in this afternoon.

47. 47 6. ELiTES activities 47 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.

48. 48 6. ELiTES activities 48 A total of 25 visitors supported by ELiTES in 2013 Note : Short stay for meeting is not counted. Germany (A total of 8 persons) Jena (A total of 6 persons), Hannover (2 persons) Netherlands NIKHEF (2 persons) United Kingdom Glasgow (3 persons) Italy (A total of 12 persons) Rome (3 persons), Sannio (A total of 9 persons)

49. 49 6. ELiTES activities 49 ELiTES in 2014 has already started ! Ettore Majorana (Rome) : Last week ! Discussion for cryogenic payload and vibration isolation Ronny Nawrodt and Stefanie Kroker (Jena) arrived this morning ! Cryogenic experiment

50. 50 7. Summary Schedule Schedule is quite aggressive. We need initial phase suspension. Later it will be replaeced by final phase one. Design of initial phase suspension should be finished by next May. Overall design Discussion with Stanford Small team for design (short meeting every morning) Preliminary design document http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2106

51. 51 7. Summary Sapphire suspension Research and development for components (quality checks of fibers, design of blade spring, test for many kinds of bonding) are finished or in progress. New fibers with square nail heads will be delivered at the end of February. Heat link Dan Chen (vibration) and Yusuke Sakakibara (initial cooling time) report later. ELiTES A total of 25 visitors in 2013. So far, 3 visitors in 2014.

52. 52 Thank you for your attention !

53. 53 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

54. 54 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

55. 55 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

56. 56 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 …

57. 57 After Yusuke left …. Clamp for IMPEX fibers in Jena 4. Sapphire fibers

58. 58 Profile measurement in Glasgow 4. Sapphire fibers

59. 59 Q measurement in Jena 5. Sapphire suspension Sapphire fibers with nail heads

60. 60 Outline of vibration isolation and cryostat 60 2 Pulse tube cryocoolers Pulse tube cryocoolers Baffles Cryoduct Outer shield (80K) Inner shield (8K) Vacuum chamber (300K)