1. 1 Kazuhiro Yamamoto Institute for Cosmic Ray Research The university of Tokyo LCGT internal review (Cryogenic payload) 30 January 2012

2. 2 I explain the cryogenic payload. This is a part of cryogenics, but it is also related with vibration isolation system.

3. 3 1. Overview 1.1 Definition of cryogenic payload System to suspend the cooled mirrors It is surrounded by the inner radiation shields. 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) Facility : Clean room Mirror : How to suspend mirror, coating mechanical loss Auxiliary Optical Systems : Monitors and scattering light Main interferometer : Control Digital systems and Electronics : Control

5. 5 1. Overview 1.3 Design phase Cryogenic payload is not necessary in iLCGT. However, the development should be in progress for bLCGT in iLCGT phase. For final design for bLCGT, (a) 1/4 cryostat in Kashiwa 1/4 means number of cryocooler, not size. (b) Some R&D items should be in progress in the iLCGT phase.

6. 6 2. iLCGT 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)

7. 7 2. iLCGT 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

8. 8 2. iLCGT 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)

9. 9 2. iLCGT 2.3 Schedule -2013 Mar : 1/4 cryostat will arrive at Kashiwa. 2013 Apr -2014 Sep : Experiment of 1/4 prototype R&D items 2014 Jul -2015 Mar : Procurement for bLCGT

10. 10 2. iLCGT 2.4 Quality assuarance (a) 1/4 cryostat : almost all items (b) Sapphire fibers, material of mass and wires: Measurement of thermal conductivity, Q-values, and tensile strength (KEK) (c) Measurement of mechanical Q of coating (KEK) (d) Vertical spring in cryostat Design and measurement of resonant frequency and Q-values (NAOJ and ICRR) (e) Transfer function of heat link : Simulation (f) Vibration measurement of radiation shield : ? (g) Baffles for scattered light : ?

11. 11 2. iLCGT 2.5 Installation Sceanario -2013 Mar : 1/4 cryostat will arrive at Kashiwa 2013 Apr -2013 May : Vacuum test and cooling test without payload Assembling payload 2013 Jun : Installation of payload, cooling test 2013 Jul – 2014 Sep : Cooling test, damping and control test -2014 Sep : All other R&D items are finished. Final design is fixed. 2014 Jul -2015 Mar : Procurement for bLCGT

12. 12 2. iLCGT 2.5 Installation Sceanario Human resources 1/4 cryostat : 3 ? 6 items of R&D : 7 ? Cryogenic experiment apparatus for R&D KEK (small vacuum flask for liquid helium), ICRR (CLIK), ICRR (small cryocooler from Mio lab) Other cryogenic apparatus ?

13. 13 2. iLCGT 2.6 Risk management (a) Sapphire fibers (P= 2, S=3, R= 6) Silicon ??? (b) Vibration via heat link (P=2, S=2, R=4) Measurement and simulation of shield vibration and heat link transfer function (c) Vertical spring in cryostat (P=2, S=2, R=4) Development should be in progress. ((d) Baffles for scattered light (???)) Discussion should be in progress.

14. 14 2. iLCGT Current status Preparation for 1/4 cryostat (Tokoku)

15. 15 2. iLCGT Current status Sapphire fibers from Moltech (Uchiyama)

16. 16 2. iLCGT Current status Cryogenic payload meeting (almost) every month from July 2011 http://gwwiki.icrr.u-tokyo.ac.jp/JGWwiki/LCGT/subgroup/vacuum Mailing list : 23 members

17. 17 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) Bonding (Shibata, Ushiba, Suzuki) Material selection for mass and wire (Tokoku) Reflectance of DLC (Sakakibara) Vertical spring in cryostat (Ishizaki, Sekiguchi) 2. iLCGT

18. 18 3. bLCGT 3.1 Requirement (a) The temperature of the mirror should be below 20 K. (b) Control (and damping) of the position and angle of mirrors at cryogenic temperature. (c) The sensitivity is not limited by the thermal noise, external vibration noise, and control noise.

19. 19 3. bLCGT 3.2 Preliminary design 1/4 cryostat

20. 20 3. bLCGT 3.3 Schedule 2015 Jun - 2016 Sep Type A (including cryogenic payload) Installation and commissioning for end mirrors 2015 Nov – 2016 Dec Type A (including cryogenic payload) Installation and commissioning for front mirrors

21. 21 3. bLCGT 3.4 Prototype test 1/4 cryostat

22. 22 3. bLCGT 3.5 Quality assuarance 1/4 cryostat and R&D

23. 23 3. bLCGT 3.6 Installation scenario 2015 Jun - 2016 Sep : X-End mirror 2015 Jun – 2015 Jul: Type A installation 2015 Jul -2015 Dec: Cryogenic payload installation and test with fixed Type A 2016 Jan – 2016 Jul: Type A + Cryogenic payload test 2016 Jul – 2016 Sep: Mirrors are replaced by sapphire ones.

24. 24 3. bLCGT 3.6 Installation scenario 2015 Jul – 2016 Sep : Y-end mirror 2015 Jul – 2015 Aug : Type A installation 2015 Aug – 2016 Feb : Type A test with dummy load 2016 Feb – 2016 Jul : Cryogenic payload installation and test 2016 Jul – 2016 Sep : Mirrors are replaced by sapphire ones.

25. 25 3. bLCGT 3.6 Installation scenario 2015 Nov – 2016 Dec : Front mirrors 2015 Nov – 2016 May : Type A installation and commissioning 2016 Sep – 2016 Dec : cryogenic payload installation and commissioning

26. 26 3.6 Installation scenario 3. bLCGT M. Ando http://gwdoc.icrr.u- tokyo.ac.jp/DocDB/0007/M1200773/001/ Roadmap_recom111231_7.pdf

27. 27 3. bLCGT 3.6 Installation scenario Human resources 3 person for 1 cryostat ? 2015 Jul – 2016 Feb : 3 persons 2016 Feb – 2016 Dec : 6 persons If persons for Type A also works for cryogenic payload, 12 persons should work from 2015 Nov to 2016 May.

28. 28 3. bLCGT 3.7 Risk management (a) Operation of Type A with cryogenic payload (P=?, S=3, R=?) No test outside the mine Installation and commissioning of Type A and B are parallel. We should learn many lessons in R&D. (b) Short installation time for front mirrors (3 months) (P=3, S=?, R=?) We should learn many lessons about end mirrors.

29. 29 Appendix A. Items that have been reduced in cost None

30. 30 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) : ???

31. 31 Human resources iLCGT : Engineers, graduate students, Post docs bLCGT : 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.

32. 32 2. iLCGT 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)

33. 33 2. iLCGT 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