27/Aug./2015 KAGRA f2f meeting N. KIMURA High Energy Accelerator Research Organization, KEK Progress status of Cryogenic System at KAGRA site

27/Aug./2015 KAGRA f2f meeting 2 Outline Over View of KAGRA Cryogenics Components of the Cryogenics Construction of Cryostat Proposed Work Schedule Summary

m Vacuum ducts along laser beam Vibration isolation system (room temperature ) Clean booth Design drawing with tunnel and cross section Cryostat (Here is a mirror) 2 nd floor Shaft A. Hagiwara Structure of vibration isolation and cryostat

Progress status of assembling the cryostats; EXC & EYC were assembled as vacuum vessels without duct shields and cryo-coolers from the end of to the end of IYC & IXC were assembled with all of components such as duct shields and cryo-cooler units from the end of to the mid of EYC EXC IXC IYC Duct Shield 12 mL vacuum duct 6 mL +6 mL vacuum duct Cryostat Gate Valve BS 3 km Cryo-cooler unit installation

BS 3 km IXC IYC EYC EXC View of Assembled Cryostats Reached pressure in the Y-front cryostat 3.7x10 -7 kPa

27/Aug./2015 KAGRA f2f meeting X&Y-end cryostats Leak test were cleared based on KAGRA requirement < 1x Pa*m 3 /sec No excess leak found above the background (~1x Pa*m 3 /sec) X&Y-front cryostats At leak test, two small leak spots < 1x10 -9 Pa*m 3 /sec were founded by the reason of malfunction of gaskets. It should be replace until mid of September Leak test

27/Aug./2015 KAGRA f2f meeting Proposed Future Plans of KAGRA Cryogenics Jan./’16 We are here July, 23rd Re-align position of EXC&EYC, and connect cross tube between cryostat and vacuum vessel for VIS. Operation of iKAGRA Connect cryo-coolers and duct shields to EXC&EYC Performance test with confirming vibration in the cryostat Connect compressors, flexible horse and cables to cryostat Jan./’17June/’16 June/’17 up grade work to bKAGRA Apr./’16~May/’16 June/’16~July/’16 Aug./’16~Oct./’16 We have already proposed above schedule to SEO. We would like to complete KAGRA cryogenic system for next year.

27/Aug./2015 KAGRA f2f meeting Summary 8 Completed assembling X&Y-end cryostats without cryo-coolers and cleared leak tests based on KAGRA requirement Completed assembling X&Y-front cryostat including connection of 11 cryo-cooler units and 4 duct shields. At leak test of the front, two small leak spots < 1x10 -9 Pa*m 3 /sec were founded by the reason of malfunction of gaskets. It should be replace until mid of September A plan for connection of cryo-cooler units and duct shields at X&Y-end cryostat were proposed and accepted by SEO. It should be launched at mid of March 2016.

9 KAGRA Cryogenics Group Toshikazu SUZUKI EO and SEO member KEK, Senior Fellow Nobuhiro KIMURA Cryostat sub-chief KEK, Assoc. Prof. Kazuhiro YAMAMOTO Cryo-Payload sub-chief ICRR, Project Assist. Prof. Takayuki TOMARU Chief KEK, Assoc. Prof. Tatsuya KUME Surveying, Alignment KEK, Assoc. Prof. Rahul KUMAR Simulation, Payload KEK, PD Ayako HAGIWARA CAD KEK, Technical Staff Shinichi TERASHIMA Machining KEK, Technical Staff Iwao MURAKAMI Welding, Assembly KEK, Technical Staff Hiroki TANAKA Cryo-Payload, Q ICRR, Grad. Student Takahiro MIYAMOTO Cryo-Payload ICRR, Grad. Student Suguru TAKADA Cryogenics NIFS, Assist. Prof Jul.25 By T. Tomaru (Revised by K. Yamamoto)

27/Aug./2015 KAGRA f2f meeting Conceptual Design of the Cryogenics Four 4K cryocooler units per one cryostat Baffles against wide scattering is cooled via 8K shield. Main Beam Cooling 8K shield Cooling Cryo-Payload Duct Shield 400kW 4W? ~1W Cryostat 80K shield 8K shield two units 80K PTC with Vibration reduction 4K PTC with Vibration reduction two units 2 units for cool cryo-payload 2 units cool for 8K shield 4 units cool for 80K shield Low vibration in U. H. Vacuum Stop propagation of 300K radiation Prevent heating by scattered beam 300K Radiation Baffles

27/Aug./2015 KAGRA f2f meeting Gate valve Connection Port to SAS Mirror a cryostat Location of Four Mirror Cryostats in Kamioka Mine Constructed at the position of 1 km in depth. Mozumi-End Atotsu-End X-Front Room Y-Front Room L=5 m Vacuum duct  800 with radiation shield

27/Aug./2015 KAGRA f2f meeting Structure of KAGRA Cryostat Seismic Attenuation System (SAS) Duct Shield Four Cryocooler Units Main Laser Beam Radiation Shields 4.3 m  2.6m Cryogenic Payload Sapphire Mirror (  -alumina crystal) S.Koike View Ports Stainless steel t=20mm Diameter 2.4 m Height ~4.3 m M ~ 12 ton Cold Mass: 8K shield ~455 kg 80 K shield ~590 kg Cryocoolers Pulse tube, 60Hz 0.9 W at 4K (2nd) 36 W at 50K (1st)

27/Aug./2015 KAGRA f2f meeting Recommendation 18: The basic performance test/inspection, especially leak tests, should be completed before the beam tube installation. The current plan to do this by the coming January should be kept.  Suzuki: The leak test of Cryostat in X-end was performed in January The top flange of the cryostat with a diameter of 2400 mm was fastened using a metal gasket. This part will never be able to open after constructing a clean booth. No excess leak was found on the background level of 1x10^-12 Pa*m^3 /sec. This result satisfied the requirement of KAGRA vacuum system that specify a leak less than 1x10^-10 Pa*m^3 /sec. Assembling other three cryostats in Y-end and XY-front is in progress. Leak test for those cryostats will finish until April Recommendation: Vibration measurements with the cryo-cooler in operation should be repeated at appropriate locations corresponding to the final design configuration, to more accurately assess vibration transfer. If the resulting spectrum remains as serious as was presented from the preliminary measurements shown, more understanding and development of mitigation techniques will be necessary. This may have radical impact on the cryogenic plant and/or payload designs. Comment: All the cryocoolers have been delivered to the KAGRA site, but cryocoolers have not all been integrated with the end cryostats. Although the cooling time for the radiation shield and vibration levels at the shield have been measured at Toshiba facility, it is highly desirable to demonstrate the cooling and vibration levels inside the real cryostat at the KAGRA site as soon as possible to alleviate remaining uncertainties about the cryogenic operation of KAGRA. If isolation of cryocooler vibration should be insufficient, it could render the vibration isolation achieved by super-attenuators useless. Recommendation: The cryocoolers should be integrated with at least one end cryostat and vibration isolation system, so that both cooling and vibration isolation can be tested as soon as possible. This will also afford VIS and CRY teams an opportunity to work together on integration of their systems PAB 2015 External Review