1. 1 Kazuhiro Yamamoto Institute for Cosmic Ray Research The University of Tokyo KAGRA external review (Cryogenic payload) 18 April 2012

2. 2 I explain the cryogenic payload. This is a part of cryogenics, but it is also related with vibration isolation system. There are some minor corrections in document.

3. 3 1. Overview 1.1 Definition of cryogenic payload System to suspend the cooled mirrors It is under vibration isolation system and surrounded by thermal radiation shields. Border between vibration isolation and cryogenics. Other items in cryostat (e.g. baffles) are also considered.

4. 4 1. Overview 1.2 Important interface Cryogenic : Heat link and cryostat Vibration isolation : Type-A (development, installation, commissioning) Mirror : How to suspend mirror, Coating mechanical loss, Clean room Facility : Clean room Main interferometer : Control of payload Digital systems and Electronics : Control Auxiliary Optical Systems : Baffle for scattering light and monitors

5. 5 1. Overview 1.3 Design phase Cryogenic payload is not necessary in i-KAGRA (room temperature interferometer). However, the development should be in progress for b-KAGRA in i-KAGRA phase. Some cryogenic payload will be installed in i-KAGRA phase.

6. 6 2. i-KAGRA Cryogenic payload is not necessary in i-KAGRA (room temperature interferometer). Nothing for i-KAGRA

7. 7 3. b-KAGRA 3.1 Requirement (a) Installation in safe and clean within the short period (b) The temperature of the mirror should be below about 20 K (with about 1 W heat load). Inital cooling time shoud be short (1 month). (c) Control (and damping) of the position and angle of mirrors at cryogenic temperature. (d) The sensitivity (10 Hz - 100 Hz) is not limited by the thermal noise, external vibration noise, and control noise.

8. 8 3. b-KAGRA 88 Cryogenic mirror Cryostat Vibration Isolation (Type-A) 14m in height Type-A and Cryogeni payload 3.2 Preliminary design

9. 9 3. b-KAGRA 999 Sapphire mirror (20K) Sapphire fiber Shield (8K) Cryogenic payload 3.2 Preliminary design

10. 10 3. b-KAGRA 10 3.2 Preliminary design Preliminary.

11. 11 3. b-KAGRA 11 3.2 Preliminary design Initial cooling time (by Y. Sakakibara)

12. 12 3. b-KAGRA 12 3.2 Preliminary design Mirror temperature (by Y. Sakakibara)

13. 13 3. b-KAGRA 13 3.2 Preliminary design External vibration (via heat link) (by T. Sekiguchi)

14. 14 3. b-KAGRA 14 3.2 Preliminary design Baffle for the (large angle) scattered light Design from Mike Smith – Caltech (support from LIGO and U.S. National Science Foundation ) Needs suspension inside radiation shield !

15. 15 3. b-KAGRA 15 3.2 Preliminary design What should we do in near future ? (1) How to assemble Details of construction in clean room …. (2) Control and damping system to reduce fluctuation and instability Actuators (what and where), resonant mode (frequency and Q) and so on (3) Noise : Thermal noise, noise of control and damping system… (4) How to suspend baffle for scattered light

16. 16 3. b-KAGRA 16 3.3 Schedule Cryogenic payload must be prepared in i-KAGRA phase (by Dec. 2015). In i-KAGRA phase, (a) We propose experiment of 1/4 cryostat in ICRR (Kashiwa) to check payload perfomance. 1/4 means number of cryocooler, not size. (b) Other R&D After these investigations, cryogenic payloads will be procured and installed.

17. 17 3. b-KAGRA 3.3 Schedule Mar. 2013 : 1/4 cryostat will arrive at Kashiwa. Apr. 2013 - Sep. 2014 : Experiment of 1/4 prototype Apr. 2013 - May 2013 : Vacuum test and cooling test without payload Assembling payload Jun. 2013 : Installation of payload, cooling test Jul. 2013 - Sep. 2014 : Cooling test, damping and control test - Sep. 2014 : R&D items (sapphire fibers...) Sep. 2014 : Final design for payload Jul. 2014 - Mar. 2015 : Procurement for b-KAGRA

18. 18 3. b-KAGRA 3.3 Schedule Jun. 2015 - Sep. 2016 Type-A (including cryogenic payload) Installation and commissioning for end mirrors Nov. 2015 – Dec. 2016 Type-A (including cryogenic payload) Installation and commissioning for front mirrors

19. 19 3. b-KAGRA 3.4 Prototype test (1) 1/4 cryostat in Kashiwa (a) How to assemble and install (b) Cooling test (initial cooling and mirror temperature) (c) Control and damping system (including parametric instability) 1/4 cryostat and its payload are not same as those of KAGRA. Number of cryocooler (not 4, but 1) Mirror and fibers are not sapphire.

20. 20 3. b-KAGRA 3.4 Prototype test Cryocooler for 1/4 cryostat has already arrived at Kashiwa.

21. 21 3. b-KAGRA 3.4 Prototype test 21 Design of 1/4 cryostat is in progress. Preliminary.

22. 22 3. b-KAGRA 3.4 Prototype test (2) Some R&D items (a)Sapphire fibers to suspend mirror (b)Vertical spring in cryostat (c)Material for mass and wire (except for the mirrors and fibers to suspend mirror) (d)Development and test of sensors, actuators, motors in cryostat (e) Thermal noise (Calculation, Q measurement of wires and coating and so on) (f) Seismic noise, external vibration noise (vibration of shield, transfer function of heat link) (g) Baffles for scattered light

23. 23 3. b-KAGRA 3.4 Prototype test Sapphire fibers to suspend sapphire mirrors

24. 24 3. b-KAGRA 3.4 Prototype test 24 Sapphire fibers to suspend sapphire mirrors Test sample (T. Uchiyama)

25. 25 3. b-KAGRA 3.4 Prototype test 25 Sapphire fibers to suspend sapphire mirrors Sapphire fibers from MolTech GmbH (Germany) Length = 350 mm diameter = 1.8 mm Almost as needed in bKAGRA. Need to check the quality.

26. 26 3. b-KAGRA 3.5 Quality assuarance Before procurement : We should check in experiment in 1/4 cryostat and the other R&D items. After procurement : We should check the parts in Kashiwa, KEK (Tsukuba) or Kamioka site. Test of sapphire fibers We pick up some fibers for test (thermal conductivity, mechanical Q-value, strength). The other fibers are installed in cryogenic payload.

27. 27 3. b-KAGRA 3.6 Installation scenario Jun. 2015 - Sep. 2016 : X-End mirror Jun. 2015 - Jul. 2015 : Type-A installation Jul. 2015 - Dec. 2015: Cryogenic payload installation and test with fixed Type-A Jan. 2016 - Jul. 2016 : Type-A + Cryogenic payload test Jul. 2016 - Sep. 2016 : Mirror is replaced by sapphire one.

28. 28 3. b-KAGRA 3.6 Installation scenario Jul. 2015 - Sep. 2016 : Y-end mirror Jul. 2015 - Aug. 2015 : Type-A installation Aug. 2015 - Feb. 2016 : Type-A test with dummy load Feb. 2016 - Jul. 2016 : Cryogenic payload installation and test Jul. 2016 - Sep. 2016 : Mirror is replaced by sapphire one.

29. 29 3. b-KAGRA 3.6 Installation scenario Nov. 2015 - Dec. 2016 : Front mirrors Nov. 2015 - May 2016 : Type-A installation and commissioning (Jun. 2016 - Aug. 2016 : Dual Recycling Michelson Interferometer (DRMI) experiment at room temperature) Sep. 2016 - Dec. 2016 : Cryogenic payload installation and commissioning

30. 30 3. b-KAGRA 3.7 Risk management Risk 9 Budget after March of 2013 (P=3, S=3, R=9) No budget, no cryogenic payload Delay of budget may change schedule and make process of development complicate. We must win budget !

31. 31 3. b-KAGRA 3.7 Risk management Risk 6 (a) Human resources (P=2, S=3, R=6) : Appendix C (b) Clean room for mirrors, payload, cryostat, and SAS (P=3, S=2, R=6) We (or new associate professor of ICRR ?) should prepare clean room. (c) Sapphire fibers (P= 2, S=3, R= 6) Invesitgation and human resources (or silicon ???)

32. 32 3. b-KAGRA 3.7 Risk management Risk 4 (a) Vibration via heat link (P=2, S=2, R=4) Measurement and simulation of shield vibration and heat link transfer function Careful design (b) Vertical spring in cryostat (P=2, S=2, R=4) Development should be in progress.

33. 33 3. b-KAGRA 3.7 Risk management Risk 4 (c) Operation of Type-A with cryogenic payload (P=2, S=2, R=4) No test outside the mine We should learn many lessons in R&D and need some tests in Kamioka mine. (d) Short installation time for front mirrors (3 months) (P=2, S=2, R=4) We should learn many lessons about end mirrors (or adjust the schedule of DRMI experiment).

34. 34 3. b-KAGRA 3.7 Risk management Risk 4 Other items (P=2, S=2, R=4) Some troubles in cryogenic experiment Assembling payload Baffles for scattered light in cryostat Control and damping system Procurement of key component Unexpected long cooling and heating time Unexpected extra heat load Electric noise from cryostat Lack of space in cryostat

35. 35 Appendix A.Design changes after first external review None

36. 36 Appendix B. Items that have been reduced in cost None

37. 37 Appendix C. Human resources Before installation of payload, Technical staffs, graduate students, Post docs Experiment of 1/4 cryostat : 3 persons Other R&D items : 7 persons Cryogenic experiment apparatus for R&D KEK (two small vacuum flasks for liquid helium) ICRR (CLIK, small cryocooler from Mio lab) Other ?

38. 38 C. Human resources In installation of payload : Thechnical staffs 3 persons for 1 payload Jul. 2015 - Feb. 2016 : 3 persons for payload Feb. 2016 - Dec. 2016 : 6 persons for payloads If persons for Type-A are taken into account, Jun. 2015 - Jul.2015 : 3 (Type-A) Jul. 2015 - Oct. 2015 : 3 (payload) + 3 (Type-A) Nov. 2015 - Feb. 2016 : 3 (payload) + 9 (Type-A) Feb. 2016 - May 2016 : 6 (payload) + 6 (Type-A) Jun. 2016 - Dec. 2016 : 6 (payload) Appendix

39. 39 Thank you for your attention !

40. 40 2. i-KAGRA Current status Sapphire fibers from Moltech (Uchiyama)

41. 41 Human resources i-KAGRA : Engineers, graduate students, Post docs b-KAGRA : Engineers 1/4 cryostat and R&D items are sources of themes for graduate students and Post docs (by 2015 March). If you (or your students) are graduate students in Ph.D. course, the strategy should be considered carefully.

42. 42 2. i-KAGRA 2.2 Final design In principle, the design is in progress. (a) 1/4 cryostat It is similar to the actual payload (except for sapphire mirror and fibers). (b) Sapphire fibers : 30 cm in length, 1.6 mm in diameter 4 fibers suspend 23 kg mirror. Clamps on the both sides (c)Vertical spring in cryostat About 1 Hz resonance, 300 kg load (d)Baffles for scattering light (discussion started)

43. 43 2. i-KAGRA Current status Cryogenic payload meeting (almost) every month from July 2011 http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/KAGRA/subgroup/vacuum Mailing list : 23 members

44. 44 3.6 Installation scenario 3. b-KAGRA M. Ando http://gwdoc.icrr.u- tokyo.ac.jp/DocDB/0007/M1200773/001/ Roadmap_recom111231_7.pdf

45. 45 Current status R&D items in progress Simulation for initial cooling time (Sakakibara) Thermal and mechanical simulation (Koike) Mechanical simulation (including thermal noise) (Sekiguchi) Simulation for transfer function of heat link (Aso) Calculation of thermal noise (Yamamoto) Sapphire fibers (Shibata, Ushiba, Chen, Suzuki) Material selection for mass and wire (Tokoku) Reflectance of DLC (Sakakibara) Vertical spring in cryostat (Ishizaki, Sekiguchi) 3. b-KAGRA

46. 46 Interface Control Document Strategy to fill the list (a)Actuators (Table 1) http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ListBy?authorid=13 (b)Emissivity of baffles (Table 2) : ??? (c) Parameters of cryogenic payload (Tables 3, 4, 15, 16) Not perfect, but report is here. http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=570 (d) Accelerometer, seismometer (Table 7) : Shield ? (e) Scratches and sleeks of mirrors (Table 12) : ???

47. 47 2. i-KAGRA 2.1 Target specification (2) Some R&D items (a)How to suspend mirrors using sapphire fibers (b)Vertical spring in cryostat (c)Development and test of sensors, actuators, motors in cryostat (d) Thermal noise (Q measurement of wires and coating and so on) (e) Seismic noise, external vibration noise (vibration of shield, transfer function of heat link) (f) Baffles for scattered light

48. 48 3. b-KAGRA 2.1 Target specification (1) 1/4 cryostat in Kashiwa (a) How to assemble and install (b) Cooling test (c) Damping and control (including parametric instability)

49. 49 3. b-KAGRA 3.3 Schedule Mar. 2013 : 1/4 cryostat will arrive at Kashiwa. Apr. 2013 - Sep. 2014 : Experiment of 1/4 prototype - Sep. 2014 : R&D items (sapphire fibers...) Sep. 2014 : Final design for payload Jul. 2014 - Mar. 2015 : Procurement Jun. 2015 - Sep. 2016 : Installation and commissioning for end mirrors Nov. 2015 - Dec. 2016 : Installation and commissioning for front mirrors