Status of KAGRA Cryogenics III Installation and cooling of cryogenic mirror payload on KAGRA site Kazuhiro Yamamoto, Yuki InoueAB, Ayako UedaA, Takafumi UshibaC,Toshiro OchiC, Nobuhiro KimuraA, Rahul KumarA, Toshikazu SuzukiC, Suguru TakadaD, Hiroki TanakaC, Shinichi TerashimaA, Takayuki TomaruA, Yoshikazu NamaiA, Ayako HagiwaraA, Kunihiko HasegawaC, Masashi FukunagaC, Helios VoccaE, Takahiro MiyamotoC, Isao MurakamiA, Tomohiro YamadaC, Takaharu ShishidoA, Toshiya Yoshioka,Takashi UchiyamaC, Takaaki KajitaC, Shinji MiyokiC Department of Physics University of Toyama, AKEK, BAcademia Sinica, CICRR, DNIFS, EINFN Perugia 2018 March 22 The meeting of Physical Society of Japan @Noda campus, Tokyo University of Science, Noda, Chiba 1 1 1 1

KAGRA Cryogenics subGroup Members in Japan Takayuki TOMARU Chief KEK, Assoc. Prof. Nobuhiro KIMURA Cryostat sub-chief KEK, Assoc. Prof. Kazuhiro YAMAMOTO Sapphire sub-chief UToyama, Assoc. Prof. Takafumi USHIBA Cryo-Payload sub-chief ICRR, PD Toshikazu SUZUKI Cryostat, Payload KEK, Prof. Rahul KUMAR Simulation, Payload KEK, PD Suguru TAKADA Cryogenics NIFS, Assist. Prof. Members from Taiwan Members in Italy Helios VOCCA HCB, Perugia U, Assist. Prof. Yuki INOUE Cryogenic Payload AS, PD

Technicians No Photo Shinichi TERASHIMA Yoshikazu. NAMAI Ayako UEDA Machining KEK, Technical Staff Yoshikazu. NAMAI Welding, KEK Technical Staff Ayako UEDA Exp. Assistant, KEK Technical Staff Ayako HAGIWARA CAD KEK, Technical Staff No Photo Isao MURAKAMI Machining KEK, Technical Staff

Students Hiroki TANAKA Takahiro MIYAMOTO Kunihiko HASEGAWA Cryo-Payload, Q ICRR, D2 Takahiro MIYAMOTO Cryo-Payload ICRR, D2 Kunihiko HASEGAWA Cryo-Payload ICRR, D1 Tomohiro YAMADA Cryo-Payload ICRR, M2 Toshiro OCHI Cryo-Payload ICRR, M2 Masashi FUKUNAGA Cryo-Payload ICRR, M1 Takaharu SHISHIDO Cryo-Payload KEK, M1

0. Abstract Here, I explain (1) Progress and future plan at KAGRA site (2) Investigation items in cryogenic payload (Details are presented in this session) 5

Items in cryogenic payload Future plan Summary Contents Introduction Progress at site Items in cryogenic payload Future plan Summary 6

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 (Type A), Cryocooler unit, Cryostat, Cryogenic payload 7 7 7 7 7 7 7 7

Vibration isolation system Vacuum ducts along laser beam 1. Introduction Outline of vibration isolation and cryostat Design drawing with tunnel and cross section 2nd floor A. Hagiwara Vibration isolation system (room temperature) 14 m K. Okutomi 22pK402 4 Shaft Clean booth Vacuum ducts along laser beam Cryostat (Here the mirror is) 8 8 8

1. Introduction Schematic view of cryo-payload Heat link Sapphire mirror

1. Introduction Connection between mirror and fibers is crucial point. Schematic view of sapphire suspension Connection between mirror and fibers is crucial point. KAGRA adopts sapphire ears for this connection. Connection between mirror and ears must be strong. Hydroxide Catalysis Bonding (HCB) is adopted. This bonding is based on chemical reaction. Sapphire fibers Sapphire mirror 10 10 10 10 10 10 10 10 10 10 10

1. Introduction Connection between mirror and fibers is crucial point. Schematic view of sapphire suspension Connection between mirror and fibers is crucial point. KAGRA adopts sapphire ears for this connection. Connection between mirror and ears must be strong. Hydroxide Catalysis Bonding (HCB) is adopted. This bonding is based on chemical reaction. Sapphire fibers Sapphire mirror 11 11 11 11 11 11 11 11 11 11 11

1. Introduction Sapphire mirror 22cm 15cm 23kg （Density is 4 times larger than that of water） 12 12 12 12 12 12 12 12

2. Progress at site 2018 spring：Test run of cryogenic simple Michelson interferometer(with 2 sapphire mirrors） Y end Extra mirror It is cooled down ! ETM X end Installation of practical mirror is in progress. 3km MC PRM ETM BS IO 3km 13 13 13 13 13 13 13 13 13 13 13

2. Progress at site Cryogenic payload with extra sapphire mirror was installed (suspended by Type A at Y end) at end of November 2017. https://www.kek.jp/ja/NewsRoom/Release/20171221090000/

2. Progress at site Cryogenic payload with extra sapphire mirror was installed (suspended by Type A at Y end) at end of November 2017. https://www.kek.jp/ja/NewsRoom/Release/20171221090000/

2. Progress at site This cryogenic payload (at Y end) was cooled down at middle of March 2017. 7th of February 14th of March

2. Progress at site Direction of this cooled sapphire mirror (at Y end) was adjusted. Reflected light arrives at photo detector. ETM IO MC BS PRM 3km Light reflected by ETM arrives !

2. Progress at site Resonances of cryogenic payload of this cooled sapphire mirror (at Y end) should be suppressed (damping). Yaw motion sapphire mirror is most serious problem. Amplitude of yaw motion : 10 mrad Requirement : 1 mrad Yaw motion

2. Progress at site HCB for ears in clean room at University of Toyama September and October 2017 Two extra mirrors -> One of them was installed at Y end. January 2018 First practical mirror ! -> Installation is being in progress at X end. HCB for ears

2. Progress at site

2. Progress at site First practical sapphire mirror was transported to KAGRA site on 9th of March 2018. On 8th of March, this mirror in clean room in University of Toyama was shown to mass media. Almost all main newspapers and televisions came. Sapphire mirror https://www.u-toyama.ac.jp/education/news/2018/0312a.html https://www.jiji.com/jc/article?k=2018030801061&g=soc

3. Items in cryogenic payload Schematic view of cryo-payload Sapphire mirror is contaminated by residual gas. Power recycling to reduce shot noise (quantum fluctuation of phase of laser) could not effective.

3. Items in cryogenic payload Change of power recycling gain in 1 year operation K. Hasegawa 22pK402 8

3. Items in cryogenic payload Schematic view of cryo-payload

3. Items in cryogenic payload Outline of cryogenic payload Platform Sensor and actuator (for control and damping) Marionette Intermediate mass Sapphire Mirror 25 25 25 25 25 25 25

3. Items in cryogenic payload Outline of cryogenic payload Platform Coil magnet actuator Fluctuation of magnetic fields can shake mirrors. Marionette Intermediate mass Sapphire Mirror Coils Magnets 26 26 26 26 26 26 26

3. Items in cryogenic payload In order to evaluate magnetic field noise, magnetic moment of magnets are measured. H. Tanaka 22pK402 9 27 27 27 27 27 27 27

3. Items in cryogenic payload Outline of cryogenic payload Relative optical displacement sensor Efficiency of sensor depends on temperature. Platform Marionette Intermediate mass Sapphire Mirror 28 28 28 28 28 28 28

3. Items in cryogenic payload Calibration of optical displacement sensor at low and room temperature M. Fukunaga 22pK402 10 29 29 29 29 29 29 29

3. Items in cryogenic payload Schematic view of cryo-payload Heat link Heat path to cool down It also transmits vibration ! 30

3. Items in cryogenic payload Measurement of thermal conductivity of heat links Calculation of vibration transmitted by heat links T. Yamada 22pK402 11 31

3. Items in cryogenic payload Schematic view of cryo-payload Vibration Vibration can contaminate output of KAGRA detector via (1)Heat link (2)Scattered light Radiation shield 32

3. Items in cryogenic payload Vibration measurement T. Ochi 22pK402 12 33

4. Future plan 2018 spring：Test run of cryogenic simple Michelson interferometer(with 2 sapphire mirrors） ETM 3km MC PRM ETM BS IO 3km 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34

4. Future plan 2018 spring：Test run of cryogenic simple Michelson interferometer(with 2 sapphire mirrors） Test run : 23 April 2018 – Measurement items of Cryogenic subgroup 3km Michelson interferometer has highest sensitivity at site. Michelson interferometer can be calibrated well. Mechanical response (transfer function) of cryogenic payload Calibration of local (relative displacement) sensor Injection test (vibration, magnetic field) 35 35 35 35 35 35 35 35 35 35 35

4. Future plan After test run on spring 2018 Other three practical mirrors will be installed by spring of 2019. -> Adjustment and so on. -> Observation with LIGO and Virgo (O3) ETM Extra mirror will be replaced with practical one. Y-arm ITM MC PRM ETM BS X-arm IO ITM 36 36 36 36 36 36 36 36 36 36 36

5. Summary Progress at site One extra mirror was installed and cooled down at Y end. One practical mirror is being installed at X end. Future plan at site On spring of 2018 Test run of cryogenic simple Michelson interferometer with two sapphire mirrors. By spring of 2019 All four practical sapphire mirrors will be installed. Investigation items of cryogenic payload Details will be presented by next 5 speakers. 37

Thank you for your attention ! 38

Backup 39

2. Cryostats at site We must conduct cooling test of all cryostats by March 2017. So far, at both ends, missions for assembly and connection were over. Leak check is current main mission at both ends. Mission for two cryostats in center room will be started on November.

2. Cryostats at site So far, at both ends, missions as below were over. (2) Connection 4K cryocoolers unit to each cryostats to SAS Outline of cryostat 4 Low vibration cryocooler unit Remote valve unit S. Koike 41

3. Cryogenic payload Outline of vibration isolation and cryostat Pulse tube cryocoolers Pulse tube cryocoolers Cryo-payload 42 42 42 42 42 42 42

3. Cryogenic payload Outline of vibration isolation and cryostat Platform Recoil mass for Marionette Recoil mass for intermediate mass Recoil mass for mirror A. Hagiwara 43 43

3. Cryogenic payload Outline of cryogenic payload Mirror chain Platform Recoil mass chain Marionette Intermediate mass Thermal noise caused by recoil mass chain is small. Sapphire Mirror http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2106 44 44 44 44 44 44 44

3. Cryogenic payload Outline of cryogenic payload GAS filer Platform for vertical vibration isolation (Mirror chain is suspended) Platform Marionette Intermediate mass Sapphire Mirror 45 45 45 45 45 45 45

3. Cryogenic payload Outline of cryogenic payload Platform Alignment adjustment system Platform Marionette Simple system for high Q-value of sapphire suspension Intermediate mass Sapphire Mirror 46 46 46 46 46 46 46

3. Cryogenic payload Outline of cryogenic payload Platform Sensor and actuator (for control and damping) Marionette Intermediate mass Sapphire Mirror 47 47 47 47 47 47 47

3. Cryogenic payload Sapphire lop-eared suspension “Sapphire monolithic lop-eared suspension” One of the most important parts of KAGRA : Main sapphire mirrors are included. All parts are made from sapphire. 48

3. Cryogenic payload Blade spring Fiber with nail head on both ends Sapphire lop-eared suspension Blade spring (compensation of fiber length difference) Fiber with nail head on both ends Flat cut Nail head of fiber Mirror Ear A. Hagiwara

3. Cryogenic payload Sapphire lop-eared suspension Indium bonding on both nail heads of fiber When fibers are broken, they can be removed ! Hydroxide Catalysis Bonding between ear and mirror

3. Cryogenic payload Current hot topics (presentations in this session) R. Kumar’s talk 51 51 51 51 51 51 51 51

3. Cryogenic payload Current hot topics (presentations in this session) Assembly sapphire suspension (Bonding between ears and mirror) K. Craig’s talk (K. Yamamoto presents on behalf of him) 52 52 52 52 52 52 52 52

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3. Cryogenic payload Outline of cryostat Cryogenic payload Mirror 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

3. Cryogenic payload Outline of vibration isolation and cryostat Heat link (pure Al) Heat link (pure Al) Pulse tube cryocoolers Pulse tube cryocoolers Cryo-payload 55 55 55 55 55 55 55

3. Cryogenic payload Design A. Hagiwara proceeds with Without recoil chain Design A. Hagiwara proceeds with CAD design drawings. Almost all parts except for platform were designed. Design is based on discussion with Vibration Isolation subgroup of KAGRA. Marionette Platform Intermediate mass Mirror A. Hagiwara 56 56

3. Cryogenic payload Prototype test of cryogenic payload Two differences from actual one Platform does NOT include GAS filter. Mirror and fibers are NOT made from sapphire, but metal. 57

3. Cryogenic payload Prototype test of cryogenic payload Without recoil chain Prototype test of cryogenic payload Marionette, Intermediate mass, Dummy mirror, Recoil mass For (dummy mirror) has already been delivered. Marionette Intermediate mass Dummy Mirror (and recoil mass) A. Hagiwara 58 58

2. Sapphire suspension All sapphire parts for full size prototype have already been delivered (IMPEX and Shinkosha). Sapphire cylinder with flat cuts as dummy mirror Fibers with nail head Blade spring Ears 59 59 59 59 59 59 59 59

1. Introduction Schematic view of cryo-payload Sapphire suspension Pulse tube cryocoolers Pulse tube cryocoolers Sapphire fiber Cryo-payload Sapphire mirror (About 20K)

1. Introduction Schematic view of cryo-payload Sapphire suspension Pulse tube cryocoolers Pulse tube cryocoolers Cryo duct