Cryo-payload Suspension structure 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

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. AkutsuA, H. IshizakiA, F. E. Peña ArellanoA, T. SuzukiB, N. KimuraB, S. KoikeB, T. KumeB, K. TsubonoC, Y. AsoC, T. UshibaC, K. ShibataC, D. ChenD, N. OhmaeE, K. SomiyaF, R. DeSalvoG, E. MajoranaH, L. NaticchioniH, W. JohnsonI, A. CummingJ, R. DouglasJ, K. HaughianJ, I. MartinJ, P. MurrayJ, G. HammondJ, S. RowanJ , G. HofmannK, C. SchwarzK, D. HeinertK, R. NawrodtK, S. GotoL, M. TanakaL, S. IokaM, K. NakamotoM, H. NezukaM, KAGRA collaboration ICRR.UT, NAOJA, KEKB, Phys.S.UTC, Astro.S.UTD, E.UTE,S.TITF, Sannio Univ.G, INFNH, Louisiana State Univ.I , University of GlasgowJ, Friedrich-Schiller-Universitaet JenaK, Jecc TorishaL, Toshiba Keihin Product OperationsM, KAGRA collaboration

0. Abstract Although there are many topics, here, I will explain (1)Schedule (2)Overall design (3)Monolithic sapphire suspension (4)Heat links

Contents Introduction Schedule Overall design Sapphire suspension Heat links ELiTES activity Summary

1. Introduction Schematic view of KAGRA interferometer Four mirrors of arm cavity will be cooled. 3km 3km Mozumi Y-end Sakonishi X-end Kamioka mine (Underground site) Atotsu Center Vibration isolation system, Cryocooler unit, Cryostat, Cryogenic payload 5 5 5 5

1. Introduction Outline of vibration isolation and cryostat 14 m 6

1. Introduction Outline of vibration isolation and cryostat 14 m Cryogenic mirror 7

1. Introduction Outline of cryostat Cryogenic payload Mirror S. Koike to SAS Cryogenic payload Cryostat Stainless steel t20mm Diameter 2.6m Height ~3.6m M ~ 10 ton Mirror View ports 4 Low vibration cryocooler unit Cryo-coolers Pulse tube, 60Hz 0.9 W at 4K (2nd) 36 W at 50K (1st) Main LASER beam Remote valve unit S. Koike

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

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

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

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

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

2. Schedule “Official plan” 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 For sapphire monolithic suspension, so aggressive ! The suspensions will be improved step by step. Initial phase suspension before final phase one is necessary.

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).

2. Schedule “Initial phase” 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. 16 16 16

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

3. Overall design 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 18 18 18 18

3. Overall design 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. 19 19 19 19

4. Sapphire suspension 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. 20 20 20 20

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

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

4. Sapphire suspension 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 IMPEX fibers satisfy the KAGRA requirement. Sapphire fibers with nail heads Latest summary of Q and thermal conductivity Moltech IMPEX KAGRA requirement Q-value 107 1*106 5*106 at 20K -6*106 Thermal Conductivity 3000 5000 5000 at 20K [W/m/K] -6000 IMPEX fibers satisfy the KAGRA requirement.

4. Sapphire suspension Sapphire fibers with nail heads Q of IMPEX fiber (D. Chen) Requirement : 5*106 https://events.ego-gw.it/indico/conferenceOtherViews.py?view=standard&confId=7

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

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

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

4. Sapphire suspension Sapphire fibers with nail heads 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 Broken jointed end E. Majorana will visit Glasgow in this month and try strength test.

4. Sapphire suspension Sapphire fibers with nail heads 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) ! Our plan for these fibers Surface flatness check (less than l/10 (l=630nm)) Measurement of thermal conductivity and Q

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

4. Sapphire suspension Sapphire blade spring (design is in progress) 46 mm R. Kumar 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) 90 mm

4. Sapphire suspension 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) 33

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

4. Sapphire suspension 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 35

4. Sapphire suspension 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 36

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

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

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

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

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

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

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

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

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

5. Heat links 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. 46

6. ELiTES activities 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. 47

6. ELiTES activities 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) 48 48 48

6. ELiTES activities 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 49 49 49

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

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.

Thank you for your attention !

7. For future 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 The next topic is the vibration of shield. Takanori Sekiguchi calculated the vibration via heat links. Takanori assumed that vibration of heat link anchor in the radiation shield is the same as that of CLIO. But, this vibration depends on the structure of shield. So, Luca from Rome and Chen Dan will measure vibration of radiation shield of KAGRA cryostat on this autumn. Luca and Chen will measure the vertical and horizontal motion. Here, I would like to introduce Chen Dan’s activity for horizontal motion. 53

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 This is the summary. Design and discussion for ¼ cryostat is in progress. Sapphire fibers with nail head can be provided by Moltech and IMPEX. These R&D items are investigated. Other ideas for mirror suspension were proposed. Collaboration with ELiTES in progress and I hope the collaboration with university of Toyama will established near future.

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 This is the issues for development of cryogenic payload; how to assemble and install, strength, control and damping system to reduce fluctuation and instability, cooling and noise.

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 … This is the issues for development of cryogenic payload; how to assemble and install, strength, control and damping system to reduce fluctuation and instability, cooling and noise.

4. Sapphire fibers After Yusuke left …. Clamp for IMPEX fibers in Jena Ok, we must check the quality of these fibers. Now, Takafumi Ushiba and Kazunori Shibata proceed with measurement of thermal conductivity and Q-values of sapphire fibers, respectively.

4. Sapphire fibers Profile measurement in Glasgow Ok, we must check the quality of these fibers. Now, Takafumi Ushiba and Kazunori Shibata proceed with measurement of thermal conductivity and Q-values of sapphire fibers, respectively.

5. Sapphire suspension Sapphire fibers with nail heads Q measurement in Jena Ok, we must check the quality of these fibers. Now, Takafumi Ushiba and Kazunori Shibata proceed with measurement of thermal conductivity and Q-values of sapphire fibers, respectively.

Outline of vibration isolation and cryostat Vacuum chamber (300K) Inner shield (8K) Outer shield (80K) Pulse tube cryocoolers 2 Pulse tube cryocoolers OK, what is cryogenic payload ? This is the cross section of tunnel of LCGT. This tall tower is vibration isolation system. There is cryogenic payload under this vibration isolation. Cryogenic payload is in cryostat. Payload includes mirror, which is the most important part of gravitational wave detector. 2 Pulse tube cryocoolers Baffles Cryoduct 60 60 60 60 60 60