Table of Contents
2009/12/02
Run diary
| Time | Task |
|---|---|
| 19:16 | Measure the psd of the voltage between different grounds and the fridge. |
| First take the psd of the voltage between the orange ground and the fridge. Turned off lights, He level meter, and the clean room. Found that the lights close to the fridge contributed to additional noise. Take data run001~004. |
Plots of run001 to run004
Summary of noise peaks in the above plot: signals are in μVRMS/√Hz.
| Frequency (kHz) | 22.50 | 26.25 | 27.75 | 50.50 | 51.50 | 52.50 | 55.50 | 68.75 | 73.00 | 78.75 | 83.25 | 84.50 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| run001 | - | - | - | 14.9 | 24.2 | 68.2 | 606.6 | 7.5 | 2.8 | - | - | 7.9 |
| run002 | 5.5 | 36.8 | 37.7 | 14.9 | 24.2 | 68.2 | 606.6 | 7.5 | 2.8 | 2.1 | 8.7 | 7.9 |
| run003 | 5.5 | 36.8 | 37.7 | 14.9 | 24.2 | 68.2 | 606.6 | 7.5 | 2.8 | 2.1 | 8.7 | 7.9 |
| run004 | - | - | - | 14.9 | 24.2 | 68.2 | 606.6 | 7.5 | 2.8 | - | - | 7.9 |
- The noise peaks at 55.5 kHz and 68.75 kHz showed up in both the PSD's of the phC and ground signals.
- The lights over the fridge generates noise peaks at 22.5 kHz, 26.25 kHz, 27.75 kHz, 78.75 kHz, and 83.25 kHz when the fridge is grounded to the orange ground.
- West lights has no effect on the noise in the measured bandwith.
- The peaks at 27.27 kHz and 78.75 kHz may have to do with the 2nd harmonics of 55.5 kHz.
| Time | Task |
|---|---|
| 21:12 | Tried turning on and off the light over the fridge when grounding the fridge to the black ground, Cu rods, and orange grounds. The lights generated noise peaks as shown above in all 3 cases. From now on, I'll keep the east lights off. |
| 21:17 | With east lights off, compare the noise PSD when grounding the fridge differently. Take data run005 and run006. |
Plot of run001, 005, and 006
The above plot shows that the orange ground is the cleanest among the three.
| Time | Task |
|---|---|
| 21:39 | Compare phC normal noise psd with different grounds and frontend gains. Take data run007 to run012. |
Plot of run008, 9, and 12. Compare three grounds at frontend gain 1.
Plot of run007, 10, and 11. Compare three grounds at frontend gain 7.
There is no difference in the above two plots. This agrees with the observation that turning off different electronics had little to do with phonon noise.
Data list
Grounds to fridge noise
| Time | Run # | Comment |
|---|---|---|
| 19:16 | 1 | Orange ground to fridge, east side lights off. |
| 2 | Orange ground to fridge, all lights on. | |
| 3 | Orange ground to fridge, west side lights off. | |
| 4 | Orange ground to fridge, west and east lights off. | |
| 21:22 | 5 | Black ground to fridge, east lights off. |
| 6 | Cu rod to fridge, east lights off. |
phC normal noise psd
| Run 007 to 012 settings |
|---|
| T = 36.9 mK, SQUID bias = 76.63 uA, Lock point = 2.38 mV, QET C bias = -1480 uA, Output gain = 1, Frontend gain = 1/7 |
| Time | Run # | Comment |
|---|---|---|
| 21:39 | 7 | Frontend Gain=7, fridge grounded to Cu rod, phC noise psd. |
| 8 | Frontend Gain=1, fridge grounded to Cu rod, phC noise psd. | |
| 9 | Frontend Gain=1, fridge grounded to orange ground, phC noise psd. | |
| 10 | Frontend Gain=7, fridge grounded to orange ground, phC noise psd. | |
| 11 | Frontend Gain=7, fridge grounded to black ground, phC noise psd. | |
| 12 | Frontend Gain=1, fridge grounded to black ground, phC noise psd. |