Software

 

To aid in the TE calculation, use the "te_getter.pl" script in the g2p_te folder on poltarg2p2. This script reads the last 'x' data entries before unixtime 'y' (default is current time). It produces a datafile for these points and asks if you'd like to use them in a TE measurement. Then it performs the TE calculation and returns the results.

 

Assumptions:

 

  • NMR System is tuned
  • Magnet is at full field, persistent mode, leads are ramped down
  • Nose is full, run valve in manual mode

 

Prepare Frig:

 

  • Stop RB3, RB2, and RB1 (wait 2 minutes between each), if necessary
  • Close roughing and bypass valve
  • Put Run Valve, EV91120, in Manual Mode
  • Establish a STEADY Nose level somewhere between 50-65%
  • Try 0.17 on the run valve.
  • If needed only make slight changes to Run Valve for rest of TE (+/- 0.05 each 10 min)

 

Take a Baseline:

 

  • Hit "Unlock Magnet Controls" button
  • Type the full-field current in the box labeled "Setpoint" (eg: 60.882)
  • Type 3.00 into "Setrate" box, if necessary
  • Hit "To Setpoint" Button
  • Wait for leads to reach full current (approx 1 min)
  • Hit "Hold"
  • Check that leads current and magnet current are equal
  • Hit "Heater On" button
  • Wait for the 30 second timeout to expire
  • Type the baseline current into the "Setpoint" box (eg: 59.882)
  • Hit "To Setpoint" to start the magnet sweeping
  • Wait for magnet to reach baseline current (approx 6 min)
  • Hit "Hold" button
  • Put NMR into pause mode if necessary
  • Hit the Baseline button
  • Select "Create New Baseline", dialog box should then disappear
  • Change sweeps to 2000 if necessary
  • Double check that all NMR settings are where you want them
  • Hit "One Point" button to take a single nmr measurement
  • Wait for timer to count down
  • Hit Baseline button
  • Select the baseline you just took from the list of timestamps
  • Document the details of the baseline in the logbook:
    • Date Time, #Sweeps, MagCurrent, Top/Bottom, Gain, RFFreq, RFMod
  • Type full-field current into "Setpoint" box (eg: 60.882)
  • Type 3.00 into "Setrate" box, if necessary
  • Hit "To Setpoint" button
  • Wait for magnet to reach full current
  • Hit "Hold" button
  • Hit "Heater Off" button
  • Wait for 30 second timeout to expire
  • Hit "To Zero" to ramp the leads down
  • Hit "Lock Magnet Controls" button

 

Take TE measurements:

 

  • Make sure ladder is in desired target position
  • Make sure NMR is on desired channel (AND in agreement with target position!)
  • Make sure you have a STEADY Nose level with roughing and bypass valve closed
  • Use ~0.17 on the run valve (watch the nose temps.)
  • Set sweeps to 2000, if necessary
  • Hit "Take Data" button
  • Wait for timer to count down
  • Write the following in the logbook for the next 10 measurements:
    • Time, NMR Area, 4He Press, 4He Temp, 3He Press, 3He Temp, Nose Level
  • Watch data until it flattens out, if in good warm (~1.5K) semi-steady state for a while then it should take less than 30 minutes.
  • calculate the TE calibration constant using poltar@poltarg2p2$ /home/poltar/g2p_te/te_getter.pl 15
  • Type Y to run te_calc on this data
  • Move the output file te_result.txt to te_date_top/bot.txt
  • Put new Cal. Const. in under Sweeps in PDP and move on to prepare frig for polarization
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