1. Measurement of thermal conductivity of sapphire rods II Takafumi Ushiba The university of Tokyo at Hongo Tsubono Laboratory 2012/8/8KAGRA Cryogenic Payload Meeting1

2. Contents Purpose of the measurement How to measure Result Discussion Summary 2012/8/8KAGRA Cryogenic Payload Meeting2

3. Purpose of the measurement Final goal measure the thermal conductivity of Moltech and INPEX sapphire rods with nail head. Near goal measure thermal conductivity of polished Photoran’s sapphire rods near peak temperature to confirm the purity of sapphire rods is well or not. 2012/8/8KAGRA Cryogenic Payload Meeting3

4. How to measure L temperature sensor temperature sensor heater Q Heat bath 2012/8/8KAGRA Cryogenic Payload Meeting4

5. How to measure temperature sensor heater heat bath 2012/8/8KAGRA Cryogenic Payload Meeting5

6. Result 2012/8/8KAGRA Cryogenic Payload Meeting6 This time, I take three data near 30K.

7. Discussion Error bars uncertainty of offset voltage of thermometer Peak’s shape If the offset voltage of thermometer does not depend on temperature, the shape of peak of thermal conductivity is same as the real peak. 2012/8/8KAGRA Cryogenic Payload Meeting7

8. Summary I measure thermal conductivity near 30K The result has too large error bars because of the offset voltage of the temperature sensor. In this measurement, I do not confirm the purity of sapphire rod is well or not. So, I need to measure thermal conductivity of sapphire rod again near 30K. 2012/8/8KAGRA Cryogenic Payload Meeting8