1. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Johnson Noise Thermometry at High Pressure Yanbin Wang Takeshi Sanehira Ivan Getting Mark Rivers

2. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Status COMPRES support Dr. Takeshi Sanehira on board since Dec 2006 Developing JNT cell Testing new probe resistors Identify noise sources and ground loop issues Setup tests on transformers, variac, powerline filter High P-T tests, Feb ~ Apr: –Sanehira, Wang, Getting, Labenski (NIST; attempted to hire as a temp employee) First high P-T results to ~1000 K, 0.1-0.3 GPa

3. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 16 mm cell design

4. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Ambient spectra before turning on AC power supply

5. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 JNT connected to cell, supply turned on Solution: fire cell parts at 900 – 1100 C, burn off all glue and organic residues

6. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Noise Reduction: Power Supply Solution: replaced existing supply with a transformer and added a powerline conditioner (Sola) to ensure pure sinusoidal output at 60 Hz.

7. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Noise Reduction: high-frequency pickup 18 kHz 37 kHz 55 kHz 73 kHz 92 kHz Solution: Shutoff all unused electronics inside the hutch. Eliminate ground loop by defining common ground.

8. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Noise reduction: 60-Hz harmonics 200 C Solution: Apply numerical notch filters for 60 Hz (5 -10 Hz width). Apply a higher cutoff to the high-pass filter, throw away signals below 20 kHz.

9. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Test data 500 K

10. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Test data 800 K

11. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 First high T measurements to 800 K: Resistance drop near 600 K

12. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 JNT output versus Temperature

13. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 First high T results

14. COMPRES Annual Meeting, Lake Morey, VM, June 17-20, 2007 Future plans Noise reduction!! New filters for JNT (expand frequency range to 100 kHz, vs. 70 kHz) - ordered New transformer – received 16 mm cell for “zero P” calibration Smaller cells and truncations for higher P measurements Beamtime proposal for 2007-3 (measure P using diffraction) New resistors –Cermets versus sintered diamond Pyrometry cross-check