Thermal Equilibrium Measurement Procedure

This procedure has been updated to reflect changes in the target for g2p but has not yet been edited by target coordinator.

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 Fridge:

• Stop RB3, RB2, and RB1 (wait 2 mintues between each), if necessary
• 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 (approx 6 min)
• 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 to run te_calc on this data
• Put new Cal. Const. in under Sweeps in PDP and move on to prepare fridge for polarization