111 K. Yamamoto, R. Takahashi, T. Sekiguchi, Y. Sakakibara, C. Tokoku, M. Kamiizumi, U. Iwasaki, E. Hirose, T. Uchiyama, S. Miyoki, M. Ohashi, T. Akutsu A, H. Ishizaki A, T. Suzuki B, N. Kimura B, S. Koike 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, 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 Development of cryogenic payload for KAGRA II 2013 March 26 The meeting of Physical Society of University, Higashi Hiroshima, Hiroshima

2 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)Mechanical loss of coating

3 Contents 1.Introduction 2.1/4 cryostat 3.Experiments in Toshiba cooling test 4.Sapphire fibers 5.Mechanical loss of coating 6.Summary

44 1. Introduction 444 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. T. Suzuki’s talk Kamioka mine (Underground site)

5 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 (20K) 1. Introduction S. Koike

666 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) Outer shield (80K) Heat links (pure Al) Vacuum chamber (300K)

7 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

8 Bid (for parts of 1/4 cryostat) was opened ! (Jecc Torisha) Vacuum chamber has already been made. Preliminary and not latest version.

Cooling test of KAGRA cryostat is in progress. T. Suzuki’s talk 9 We have plans of experiments in Toshiba cooling test of KAGRA cryostat. Experiment 1 : Initial cooling time Experiment 2 : Measurement of shield vibration All items were installed ! Cooling is in progress. 3. Experiments in Toshiba cooling test

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

11 Al hollow spheres (100 mm in diameter) Y. Sakakibara’s small experiment in Kashiwa : 30 mm in diameter Without DLC With DLC Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test Sphere with DLC (2 nd cryostat) Sphere with SolBlack (4 th cryostat) Sphere without black coating (1 st cryostat)

12 Al hollow spheres (100 mm in diameter) Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

13 Al hollow spheres (100 mm in diameter) Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

14 Dummy payload (hollow masses, 3rd cryostat) Half size Hollow masses (~5 kg) DLC coating Sapphire bulk as dummy mirror S. Koike (100 mm in diameter) Evaluation of emissivity Experiment 1 : Initial cooling time 3. Experiments in Toshiba cooling test

15 Experiment 1 : Initial cooling time Dummy payload 3. Experiments in Toshiba cooling test

16 Experiment 1 : Initial cooling time Dummy payload Experiments in Toshiba cooling test

17 Experiment 1 : Initial cooling time Dummy payload Experiments in Toshiba cooling test

18 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 (2 nd cryostat) and horizontal (3 rd cryostat) vibration of radiation shield of KAGRA in cooling test of Toshiba, respectively. Dan Chen’s talk Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test

19 Luca’s accelerometer was installed (13 th of Feb). Experiment 2 : Measurement of shield vibration 3. Experiments in Toshiba cooling test Maurizio Perciballi Ettore Majorana also visited in March.

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

21 Experiment 2 : Measurement of shield vibration Dan’s accelerometer was installed in the shield. (8 th of Mar). 3. Experiments in Toshiba cooling test

22 Experiment 2 : Measurement of shield vibration Dan’s accelerometer was installed in the shield. (8 th of Mar). 3. Experiments in Toshiba cooling test

23 4. Sapphire fibers 23 Test sample (T. Uchiyama) Sapphire fibers with nail heads are necessary to suspend mirrors.

24 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

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

26 Quality check Q-value Measurement in Glasgow and Jena Y. Sakakibara visited for measurement. Plan for measurement in Rome and ICRR (C. Schwarz and G. Hofman’s visit from Jena) Thermal conductivity Measurement in Jena Plan for measurement in Rome and ICRR Strength test Discussion with Glasgow (Thanks for E. Hirose) 4. Sapphire fibers

27 Q measurement in Jena (cool) and Glasgow (300K) It is slightly smaller than KAGRA requirement ! Preliminary result 4. Sapphire fibers Y. Sakakibara Moltech

28 After Y. Sakakibara left …. It is comparable with KAGRA requirement ! Q measurement in Jena Preliminary result 4. Sapphire fibers Moltech C. Schwarz

29 After Y. Sakakibara left …. It is slightly smaller than KAGRA requirement ! Q measurement in Jena Preliminary result 4. Sapphire fibers IMPEX R. Douglas’s poster in LVC meeting (March 2013)

30 It is same as KAGRA requirement (size effect) Thermal conductivity measurement in Jena Preliminary result 4. Sapphire fibers T. Tomaru et al., Phys. Lett. A 301 (2002) 215. Moltech C. Schwarz

31 It is smaller than KAGRA requirement, but same order of magnitude. Preliminary result 4. Sapphire fibers Thermal conductivity measurement in Jena Moltech C. Schwarz

32 4. Sapphire fibers Thermal conductivity measurement in Jena Thermal conductivity of IMPEX fibers will be measured soon.

33 5. Mechanical loss of coating 33 Discrepancy between Tokyo and Glasgow Tokyo Glasgow K. Yamamoto et al., Physical Review D 74 (2006) I.W. Martin et al., Classical and Quantum Gravity 27 (2010)

Some samples of Japanese coating were sent to Glasgow. Y. Sakakibara measured loss of these samples in Glasgow (room temperature). Glasgow group continues the mission for the cryogenic temperature. E. Hirose is measuring mechanical loss of other Japanese samples in ICRR (University of Tokyo). Construction of the measurement system for KAGRA coating 5. Mechanical loss of coating

35 Cryostat Cryocooler Optical lever Lock in amp Experimental apparatus in ICRR 5. Mechanical loss of coating

36 Sapphire disk Inside cryostat 5. Mechanical loss of coating

Some samples of Japanese coating were sent to Glasgow. Glasgow group continues the mission for the cryogenic temperature. K. Graig (Glasgow) brings these samples and measure in ICRR again (April). E. Hirose is measuring mechanical loss of other Japanese samples in ICRR (University of Tokyo). Result is coming soon ! 5. Mechanical loss of coating

38 5. Summary 1/4 cryostat : Bid for parts was opened and vacuum chamber was made ! Experiments in Toshiba cooling test : Initial cooling time (Y. Sakakibara’s talk) Metal sphere with and without black coating 1/2 dummy payload Measurement of shield vibration (D. Chen’s talk) All items were installed ! Cooling is in progress.

39 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. Mechanical loss of coating Measurement is in progress and result is coming soon !

40 Acknowledgement 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 Feb. 2016) European people can visit Japan for KAGRA.

41 Thank you for your attention !

42 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

43 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

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

45 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

46 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 …

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

48 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

49 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

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

51 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

52 Experiment 1 : Initial cooling time Sample 2 : Dummy payload 52 Yusuke calculated the cooling time of 1/2 dummy payload. 3. Experiments in Toshiba cooling test

53 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

54 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

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

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

57 Profile measurement in Glasgow 4. Sapphire fibers

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