*Heat load Test *****Pulse tube cryocoolersPulse tube cryocoolersPulse tube cryocoolersHeater and thermometerSapphire mirrorCooling test in Toshiba

*****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 lineCooling 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.

ET-meeting, 22th Oct. 2013 N. KIMURA/KEK

Results (with copper heat links)Cryo-coolers for payloads didnt cool down completely (2nd stage stayed at 20 K)Thermal conductivity of heat links calculated from results: 1/5 of literatureThermal contact resistance between payloads and heat links**2013.9.22 2013Yusuke SakakibaraEmissivitySapphire: 0.5Platform: 0.3*(T/300K)IM: 0.4*(T/300K)

ET-meeting, 22th Oct. 2013 N. KIMURA/KEK

Measurement of thermal radiationTwo aluminum plates suspended600 mm plate (Left side) is heated up to 300 K and emits thermal radiation250 mm plate (Right side) absorbs radiation and is heated upCalibration is conducted using heater on 250 mm plateCoated with Solblack to enhance emissivity or absorptivity

Done by Y. Sakakibara*Thermal Radiation600 mm250 mm150 K250 K40 K17 mPerformance Test of the Prototype Duct Shield

Done by Y. Sakakibara

ET-meeting, 22th Oct. 2013 N. KIMURA/KEK

ResultsCalculated value has error of several timesMeasured reflectivity at 10 m of shield has errorRays are reflected by shield many timesMeasured value is within the error

*Reflectivity at 10 umDuct0.940.02Solblack0.70.1

Reduced by Duct Shield

ET-meeting, 22th Oct. 2013 N. KIMURA/KEK

Measurement of scattered lightRed light from laser diodePhotographs of scattered light when angle changesCalibration by changing exposure timeFuture work: Vibration measurement, calculation of equivalent GW amplitude Yusuke Sakakibara*~200 ppm of laser light came back to camera635 nm, 4.5 mWBackground

Yusuke Sakakibara

5Fixed pointsModal analysis for KAGRA Duct Shield800Gravitational DirectionWe analyzed the resonance peaks of the vacuum chamber without bellows and the inner shield.Mode frequency are calculated from 20 Hz to 100 Hz.

F17 77.16 Hz F18 94.00 Hz F19 96.18 Hz F20 99.86 Hz Resonant FrequencyF1 18.85 Hz F2 25.48 Hz F3 38.52 Hz F4 40.28 Hz F5 40.99 Hz F6 43.65 Hz F7 44.20 Hz F8 46.31 Hz F9 49.01 Hz F10 59.07 Hz F11 63.66 Hz F12 64.58 Hz F13 68.25 Hz F14 68.69 Hz F15 73.87 Hz F16 77.00 Hz F17 77.16 Hz F18 94.00 Hz F19 96.18 Hz F20 99.86 Hz

Shape of duct shield at each resonant frequency.It was confirmed that the most of resonant frequencies are cause of strength of the vacuum chamber, and weaker than that of inner shield.These results have been feedback to the duct shield design.

ET-meeting, 22th Oct. 2013 N. KIMURA/KEK

Structure view of the Production Duct Shield80 K Duct ShieldBellowsVacuum VesselSupport Frame5 mBaffles

ET-meeting, 22th Oct. 2013 N. KIMURA/KEK

Summary*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.Vibration on the surface of inner radiation shield.Experiment with half size of dummy cryo-payload3. Experiment with proto type duct shield was conducted, and result was agreed with predicted heat load. But, need more analysis work.4. Design of the production of duct shield were almost finished. Now, We are focusing our work on fabrication of the duct shields and preparing performance test.

*******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.

*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.

*We have to improve heat link structure including heat resistance between surfaces.**