1. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Progress on the Cryogenic System for the Interferometric Cryogenic Gravitational Wave Telescope, KAGRA N. KIMURA A, D. CHEN B, T. KUME A, S. KOIKE A, Y. SAKAKIBARA B, T. SUZUKI A, C. TOKOKU B, K. YAMAMOTO B, M. OHASHI B, and K. KURODA B A High Energy Accelerator Research Organization, KEK B ICRR, University of Tokyo,

2. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK 2 Outline Requirements for KAGRA Cryogenics Components of the Cryogenics Actual Work Schedule Performance Tests Cryocooler Unit & Cryostat 1/2 Dummy Payload Experiment Vibration Measurement Will be presented at C3 poster session as C3.9 by Mr D. CHEN Summary

3. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Requirements for KAGRA cryogenics Temperature of the test mass/mirror < 20 [K] Inner radiation shield have to be cooled to < 8 K The test mass have to be cooled without introducing excess noise, especially vibration due to cryocoolers. Easy access and enough capacity to installation work around the mirror. Allowable size as large as possible under public transport regulation on the road and in the KAGRA tunnel. Satisfy ultra high vacuum specification < 10 -7 Pa Satisfy the requirement for the Cryogenics Adopt Pulse Tube-type Cryo-cooler units with very low vibration mount based on the CLIO type cooler. Adopt  2200 of inner diameter of flanges for installation work of the test mass and its suspension. Analyzed the cryostat response to ground motion at Kamioka-mine. Heat load from components as low as possible. Develop very low out gas super insulation system for radiative heat load but also useable under ultra high vacuum < 10 -7 Pa

4. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK 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 Conceptual Cooling Scheme for the KAGRA Cryogenics

5. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK 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) Structure of KAGRA Cryostat

6. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Actual Work Schedule of Four Cryostats and Peripheral Components Manufacture components Assemble and factory test with cryo-coolers Transport to storage near Kamioka 2011 Jfy2012 Jfy2013 Jfy Apr./’12Apr./’13Apr./’14Apr./’11. Design by KEK Bidding We are here July, ’13th Four Mirror Cryostats Cryo-cooler units Design by KEK Production of seven cryo-cooler units with performance test Production of nine cryo-cooler units with performance test Transport to Kamioka Custody at Kamioka Duct shield units Design by KEK Production of three ducts shield units without cryo-coolers Performance test

7. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Cooling Power ・ > 2.5W@9K ( @ connection part of 8 K conduction bar) ・ > 35W@70K ( @ connection part of 80 K conduction bar) Vibration Characteristics ・ < ±100 x 10 -9 m ( @ connection part of 8 K conduction bar) ・ < ±100x 10 -9 m ( @ connection part of 80 K conduction bar) Photo: Performance test at ICRR Low Vibration Cryo-cooler Unit Base on CLIO type Cryo-cooler with low vibration mount for KAGRA but cooling power is lager than CLIO

8. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Performance of the low vibration cryo-cooler unit Vibration at the connection point Impulse response To suppress the vibration at 1.7 Hz below 0.1 μm/Hz^0.5, we improved on the support structure design. We measured the vibration of sixteen cryocooler units. We confirmed its vibration reduction ratio lager than 100 and less than 100 x 10 -9 m/Hz^0.5. Cooling powers of 2.5W@9K and 35W@70K were also confirmed too. Courtesy by Dr. C. TOKOKU Presented at CEC/ICMC2013, 2EPoE1-03, Anchorage, USA (2013).

9. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Results of Performance Test of the Cryostat It took 12.5 days to cool down from 300 K to 8K. Cool down time of the cryostat was consistent with the predicted cooing time by Calculation model. Performance test at Toshiba Keihin Product Courtesy by Dr. C. TOKOKU Presented at CEC/ICMC2013, 2EPoE1-03, Anchorage, USA (2013).

10. Result of Heat Load Response @ 8K Radiation Shield 10 Cooling test in Toshiba 2 W~ 5 ppm 0 W ~0 ppm 10 W ~25 ppm 5 W ~ 12.5 ppm Mirror Operation Scatted light power is 4 W @400 kW beam power when scattered loss on the mirror surface is 10 ppm. It is confirmed that 25 ppm (10 W) @400 kW of scattered loss is acceptable as heat load for the cryocoolers via the 8 K radiation shield.

11. 11 4 W 10 W 0 W According to our design, temperature should be below 8 K when heat absorption in mirror is 1 W. Result of Heat Load Response @ Cryo-payload line Cooling test in Toshiba It is confirmed that 2.5 ppm (1 W) @400 kW of mirror deposition is acceptable as heat load for the cryocoolers connected with cryo-payload line.

12. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Half Size Dummy Cryo-payload Experiment with KAGRA cryostats ½ Dummy Payloads designed and made by R. Kobayashi, S. Koike (KEK) Spare of CLIO mirror Presented at 2013.6.24 CEC/ICMC (Anchorage, Alaska) by Mr Y. Sakakibara 12 1/2 size dummy payload was suspended inside cryostat No.3 Thermal radiation was examined (without any heat links) ◦ Cooling from room temperature

13. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Results Effect of High Emissivity Coating for Cooling Time is Confirmed. It was consistent with the estimation! Emissivity Sapphire: 0.5 Platform: 0.3*(T/300K) IM: 0.4*(T/300K) 2013.6.24 CEC/ICMC (Anchorage, Alaska) Yusuke Sakakibara13 Cooling performance test with heat links is now in progress at Toshiba Keihin Product.

14. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEKSummary 14 1. KAGRA cryogenics consisting of cryostat and cryo- cooler units was designed, fabricated, and tested their performances during 2011JFY and 2012JFY. 2. At the performance test, following items were confirmed and verified; The cooling and vibration performance of sixteen cryocooler units. The cooling performance of all the four cryostats. 3. Calculation model predicts cooing time correctly, and experiment with KAGRA cryostats was verified. 4. Experiment with half size of dummy cryo-payload was conducted, and result was agreed with prediction of cooling time.

15. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Back Up

16. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK 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

17. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK 80K Cooling passage 8K Conduction Bar Valve Unit Structure view of the Low Vibration Cryo-cooler Unit バルブ台 Flexible Heat Links Bellows Part of Vibration Reduction Stage Vacuum Vessel (Support: Conduction Paths) Support Frame (Support: Cold Head) 2m 1m

18. 18 TM RM IM RM for IM Platform Cooling Time Reduction with DLC To increase cool down by radiation, form black coating with Diamond Like Carbon on outer surface of the payload and inner surface of 8K shield. S.Koike TM : Test Mass RM : Recoil Mass IM : Intermediate Mass ItemsMaterialsMass Courtesy by Y. Sakakibara Comparison of Cooling Time with & without DLC Almost half ! Without DLC With DLC

19. 19 Pulse tube cryocoolers Heater and thermometer Sapphire mirror Cooling test in Toshiba Heat Load Response @ 8K Radiation Shield

20. 20 Pulse tube cryocoolers Heater and thermometer Sapphire mirror Cooling test in Toshiba Heat Load Response @ Cryo-payload line

21. 9 th /July/2013 Amaldi 10 C3 15:24~15:42 N.KIMURA/KEK Performance test of the Cryostat Performance test at Toshiba Keihin Product 80K Shield Esti. (W) Meas. (W) ◦ Eleven View Ports (22) - ◦ Radiation From 300 K 80- ◦ Support post and Rods 7.6- ◦ Electrical wires 3 x 10 -4 - Total 88 (110)125 W/unit 22 (27.5)31 8K Shield Esti. (W) Meas. (W) ◦ View Ports (0.4)* - ◦ Radiation From 80 K 2.0 - ◦ Support post and Rods 0.3 - ◦ Electrical wires 3 x 10 -4 - ◦ Scattering Light ( < 4.0 ?) - Total2.3 (6.7 ?) <2.0 W/unit1.15 (3.4 ?) <1.0 Cryo-payload Esti. (W) Meas. (W) ◦ Payload 1.0- ◦ Mirror Deposition(1.0?)- Total1.0 (2.0 ?)- W/unit0.5 (1.0 ?) 0.4