DAQ Testing/20190628

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June 18th, 2019 Testers: Cameron Clarke, Paul King, Catherine Feldman

Raster Synch

Raster calibration run: https://logbooks.jlab.org/entry/3696278

  • Initially wasn't well tuned.
  • Changed to Free Clock
  • Now it is synched so both are synched to the 120 Hz free clock Tsettle
  • Could also change it to have both be -> integer number multiples of 120 and ignore Tsettle
  • Could also do both of these in Beam Synch Mode

Paul King later tuned the parameters to all sig figs https://logbooks.jlab.org/entry/3702608

Copy from HALOG

The Raster Frequencies before tuning the the Helicity Flip rate had been set to approximately the correct settings, but this was done during the beam sync mode of the control board. Beam sync makes it hard to see the relative phase drift of the raster frequencies w.r.t. the flip rate as the Nth (4th) helicity flip period gets a different integration time in order to allow the following multiplet to latch on the start of beam synch.

The raster settings before changing them were :

  • Channel 1 (yellow on the Agilent) - 25.07478380 kHz
  • Channel 2 (green on the Agilent) - 24.95511650 kHz

I think that channel 1 corresponds to the Y and 2 to the X raster currents (as these are the labels of their cables through patch panel land), but what X and Y mean in terms of the effect we see on the spread of the raster in the Counting Mode DAQs is still a matter of opinion on coordinate frame nomenclature choice (see raster current in Counting Mode DAQ calibration studies from Catherine:https://logbooks.jlab.org/entry/3695377)

I updated the raster synch during a free clock 120 Hz test. Set helbrd top 120 Hz (with 100us Tsettle, Tstable to 8233.35us)

Raster Frequency Synching

We want to set both frequencies to an integer multiple of 120 Hz and have their difference be 8x120 = 960 (previous experience says this may be optimal) 25kHz/120 = 208.33, so 24,960 is the sweet spot multiple of 120 I pick 25440 and 24480

New Settings taken during 100 us Tsettle and 8233.35 us Tstable

  • Channel 1 (yellow) 25.439949 kHz
  • Channel 2 (green) 24.479949 kHz


- The important observation (by eye) is that after performing this sync I see that both x and y raster signals are static (no phase drift) w.r.t. the 120 Hz helicity flip rate and w.r.t. each other. - When I first tuned them to those nice integer numbers above, I saw both were synched to each other, but that they drifted w.r.t. the 120 Hz helicity frequency. - In order to correct for this drift I tuned both frequencies the exact same amount downwards (same amount in order to preserve the difference of 8x120 Hz, and hopefully being a bit low on both will not mess up anything. This was a choice made by Cameron and Bob together)

Data taking on June 29 OWL: - After we tuned the raster we left the helicity control board in free clock mode (under clearance from Kent to do what we like) - After tuning the raster we chose to leave the trigger timings all at the prior 90us tuned parameters (I think only flexio latch was based on Tstable, so this has minimal effect) - If we still see residual correlations in the Main detectors we should try:

  • Going back to beam synch with this tuned raster
  • Tuning the raster to those nice integer numbers from before instead in free clock
  • Same, but with beam synch

Pictures of DAQ/Apparatus after test: media:XYfrequencyScope-29062019.jpeg, media:XYcurrentScope-29062019.jpeg, media:XYvoltages-29062019.jpeg, media:AgilentChannel1-29062019.jpeg, media:AgilentChannel2-29062019.jpeg

Saved settings into "120_Free_Tset" save point