Present Design of LCGT Cryogenic Payload Status of

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Present Design of LCGT Cryogenic Payload - Status of Cryogenic Design N. KIMURA*, Y.

Present Design of LCGT Cryogenic Payload - Status of Cryogenic Design N. KIMURA*, Y. SAKAKIBARA**, S. KOIKE*, T. OHMORI***, T. SUZUKI*, H. YAMAOKA*, * and LCGT Collaboration High Energy Accelerator Research Organization (KEK) ** University of Tokyo *** Teikyo University GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA

Outline • Design of the LCGT cryogenics ü Structure of the cryostat ü Cryostat

Outline • Design of the LCGT cryogenics ü Structure of the cryostat ü Cryostat response to ground motion at CLIO/Kamioka mine ü Thermal Budget of the cryostat ü Estimation of heat load of the Mirror from the beam duct shields (by Mr. SAKAKIBARA) • Summary GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 2

Location of Four Mirror Cryostats with the Cryo-coolers for the LCGT Mozumi-End Atotsu-End Y-Front

Location of Four Mirror Cryostats with the Cryo-coolers for the LCGT Mozumi-End Atotsu-End Y-Front Room X-Front Room Connection Port to SAS Mirror a cryostat Gate valve L=~20 m Vacuum duct 800 with radiation shield L=~20 m Gate valve Vacuum duct 800 with radiation shield GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA

Production plan of LCGT mirror cryostats and peripheral components 2011 Jfy ‘ 11. 3

Production plan of LCGT mirror cryostats and peripheral components 2011 Jfy ‘ 11. 3 ‘ 12. 3 We are here Four Mirror Cryostats 2012 Jfy ‘ 13. 3 ‘ 14. 3 Manufacture components Design by KEK Bidding Assemble and factory test with cryo-coolers Cryo-cooler units Design by KEK 2013 Jfy Transport to Kamioka Custody at Kamioka Performance test 1 st Prot-type Cryo-cooler unit test Production of seven cryocooler units Duct shield units Design by KEK Transport to Kamioka Performance test Custody at Kamioka Production of nine cryocooler units Production of Prot-type ducts shield units with cryo-coolers GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA

Requirements and Answers Answer to the requirements Basic requirements from LCGT cryogenic Adopt Pulse

Requirements and Answers Answer to the requirements Basic requirements from LCGT cryogenic Adopt Pulse Tube-type Cryo-cooler units • • Temperature of the test mass/mirror : 20 [K] with very low vibration mount Inner on radiation shield to be cooled to < 8 K based the CLIO typehave cooler. Adopt 2200 of to inner diameter of flanges • The mirror have be cooled without introducing for installation work of the mirror and suspension. excess noise, especially vibration due to cryocoolers. • Analysed the cryostat response to • Easy access andat enough capacity ground motion Kamioka-mine. • Heat load fromwork components as low as possible. to installation around the mirror. • Develop very low out gas super insulation system -7 Pa • Satisfy ultra high vacuum specification < 10 for radiation heat load for ultra high vacuum specification < 10 -7 Pa GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA

~3. 8 m Structure of Mirror Cryostat to SAS Cryostat Stainless steel t 20

~3. 8 m Structure of Mirror Cryostat to SAS Cryostat Stainless steel t 20 mm Diameter 2. 4 m Height ~3. 8 m M ~V 10 ton iew AS L n Mai Drawn by S. Koike (KEK) Remote valve por ts Low vibration cryocooler unit am e b ER Main beam (1200 mm FL) m 2. 4 Cryocoolers Pulse tube, 60 Hz 0. 9 W at 4 K (2 nd) 36 W at 50 K (1 st) Cryostat accompany with four cryocooler units GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA

The interior of the cryostat Drawn by S. Koike (KEK) Support rods View Ports

The interior of the cryostat Drawn by S. Koike (KEK) Support rods View Ports Double radiation shields with hinged doors Heat path to cryocooler GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA

Structure of Radiation Shields Flame made by A 6000 Aluminum Secure stiffness and conductivity

Structure of Radiation Shields Flame made by A 6000 Aluminum Secure stiffness and conductivity of the radiation shields Outer Shields GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA Inner Shields

Response to ground motion resonant frequency Cryo-top Cryo-F Cryo-L Cryo-R Y方向 X-direction X方向 Input

Response to ground motion resonant frequency Cryo-top Cryo-F Cryo-L Cryo-R Y方向 X-direction X方向 Input Y-direction

An Estimated Break Down List of Thermal Budget 1 st Cold stage • Outer

An Estimated Break Down List of Thermal Budget 1 st Cold stage • Outer Shield (W) ◦ Eleven View Ports 22 ◦ Radiation From 300 K 70 ◦ Support post and Rods 24 ◦ Electrical wires 3 x 10 -4 Total W/unit 116 29 2 nd Cold stage • Inner Shield (W) ◦ Duct Shields* < 0. 05 (Beam and SAS) ◦ Eleven View Ports 0. 4 ◦ Radiation From 80 K 2. 2 ◦ Support post and Rods 2. 4 ◦ Electrical wires 3 x 10 -4 ◦ Mirror Deposition 0. 9 ◦ Scattering Light ? Total W/unit 5. 9 1. 5 *Heat Load of Duct Shields will be told by Mr. Sakakibara GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 10

Estimated Thermal Budget Estimated Heat Loads at the radiation shields and Support posts and

Estimated Thermal Budget Estimated Heat Loads at the radiation shields and Support posts and rods 70 bythe thetop radiation 94 W K at of at the 80 80 K Koutershield 2. 27. 4 W Kbyatthe theradiation top of at the 8 K 8 inner shield K inner shield 2. 4 W by the radiation and conduction (support posts and Connection point with IM tension rods) at 8 K 24 W by the radiation and (support posts and 47 K atconduction 1 st cold stage tension rods) at 806. 5 K K at 2 nd cold of Cryo-cooler stage of Cryocooler d. T 1 st = 26 K Very High Purityd. T Aluminum 2 nd=0. 5 K Conductor (5 N 8) Low Vibration Cryo-cooler unit GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 11

Outline • Concept of the LCGT cryogenics ü Structure and Response to ground motion

Outline • Concept of the LCGT cryogenics ü Structure and Response to ground motion at CLIO/Kamioka mine ü Thermal Budget of the cryostat ü Estimation of heat load of the Mirror from the beam duct shields (by Mr. SAKAKIBARA) • Summary GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 12

Estimation of heat load from the beam duct shields of the Mirror in the

Estimation of heat load from the beam duct shields of the Mirror in the Cryostat Thermal radiation from opening of 500 mm in diameter Cooling power 3. 6 W at 4 K (inner shield, 4 pulse tube cryo-coolers of 0. 9 W at 4 K) Thermal radiation appears to be reduced by reducing solid angle GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 13

Problem experienced in CLIO Thermal radiation reflected by metal shield pipe Incident power (calculated

Problem experienced in CLIO Thermal radiation reflected by metal shield pipe Incident power (calculated using ray trace model, experimentally verified by T. Tomaru, et al. 2008 ) Very large compared with solid angle mirror 300 K 4 K GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA animation 14

Reducing heat load by baffles Incident power calculated using ray trace model by counting

Reducing heat load by baffles Incident power calculated using ray trace model by counting up number of reflections (Aluminum of A 1070 measured at 10 mm, 100 K) 300 K 4 K animation GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 15

Result of calculation R=0. 94± 0. 02 Worse case R=0. 96 P=52. 4 m.

Result of calculation R=0. 94± 0. 02 Worse case R=0. 96 P=52. 4 m. W Better case R=0. 92 P=17. 6 m. W • The better result for the case that intervals of baffles are not equal to each other – If intervals of baffles are equal, ray whose angle passes through one baffle also passes the other baffles mirror 300 K x=0 m 4 K x=20 m GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 16 16

Diamond Like Carbon coating DLC coating Heat absorbed by baffles Heat load becomes smaller

Diamond Like Carbon coating DLC coating Heat absorbed by baffles Heat load becomes smaller Baffles whose room temperature sides are coated with DLC Assuming reflectivity 0. 35 (measured at 1 mm at room temperature by T. Tomaru, et al. 2005) Preparation for measurement at 10 mm, cryogenic temperature is now underway GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 17

Summary 1 • Sum of heat load from openings of cryostat can be sufficiently

Summary 1 • Sum of heat load from openings of cryostat can be sufficiently reduced by baffles ◦ 37 m. W (18. 4 m. W x 2) ◦ Problem in CLIO solved One prototype duct shield will be constructed until the end of March, 2013. The duct shield will be tested to verify this calculation with the mirror cryostat. GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 18

Summary 2 The design of the mirror cryostat for LCGT satisfying requirements was almost

Summary 2 The design of the mirror cryostat for LCGT satisfying requirements was almost finished. The production of the components for the cryostat will be started after decided contractor. Performance of the first cryostat will be demonstrated at the factory of the contractor on the mid of 2012 Jfy. We would like to discuss the detailed design process of the cryostat with participants of GWADW conference after this talk. GWADW 2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA 19