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UMUX 5

2019-12-02

Resonances seem be be between 5.2 to 5.4 GHz. Here is a photo of the network analyzer

Found 22 clear resonances using qtTools.findresonances

Phasestream shows a strange pattern in many channels.

Tried flux ramp, cannot see the fluxramp in the phase stream.

12-05-2019

Some signs of flux ramp signal from umux, but strange.

above plot is for a flux a ramp input at 100Hz, a saw tooth wave 0-2.5V with 100% duty cycle.

Increased the flux ramp input to 0-4V, see something like the flux ramp, but with a lot of noise.

When the flux ramp input increased to -5V it disappears.

Lowered the flux ramp input back to -4V, Connected the signal cable from channel 2 of the pulse generator. (output turned off). See a distorted flux ram like signal.

fluxramp 0-3V. Signal is still turned off.

flux ramp input 0-1V. Signal still turned off.

2019-12-06

We repeated the study, and see similar results, making sure to rotate and translate. This is also done with 50 Ohm terminators on both inputs.


Here is the time stream of phases


Power spectrum of phases, zoomed in around a few hundred Hz. The first peak is 125 Hz.

Capturing many phases

We ran streamToRamDisk for a few minutes and copied data to /home/stoughto/2019-12-06-umux5 and plotted phases for different channels. The variation seems to be correlated.

Lalith discovered that unplugging the cable from the feedthrough changed the pattern. Covering the connector with foil reduced high frequency noise but the 125 Hz stayed the same.

2019-12-12

Comparing signal from board in the rack and the board prepared to send to ANL.


above: phase stream and power spectrum from the ANL board.


above: phase stream and power spectrum from the SiDet board.

2019-12-13

We are investigating the 60 Hz + harmonics noise that we are seeing in the phase timestreams. Presumably this is induced by grounding, so we are testing a few different configurations:

  1. Added a grounding strap between the wall and the cryostat. Resistance to the wall decreased, but noise is basically unchanged. (grounding-01.png)
  2. Added DB-25 connector to flux ramp and input coil. Noise got worse (grounding-02.png).
  3. Removed terminator from breakout connector. Noise is unchanged.
  4. Shorted with 0 Ohm. (grounding-03.png)
  5. Disconnected the DB-25 connector. Noise went back down to same level as grounding-01.png.
  6. Reconnected cable and added 0 or 50 Ohm termination to all BNCs on breakout box. (grounding-04.png)
  7. BNC 1 and 2 are terminated with 50 Ohm on the breakout (grounding-05.png)
  8. Unplugged the DB-25 pin connector again. Noise back down (grounding-06.png) (10x better).
  9. Plugged in DB-25 pin connector, but not into box, just dangling (grounding-07.png)
  10. Same as above, but connected to box, just dangling in free space (grounding-08.png)
  11. Moved box to top of cryostat to be in contact with top flange (grounding-09.png)
  12. Turned off pump and valved off (grounding-10.png)
  13. Unplugged pump from cryostat (grounding-11.png)