Assumptions:

 

  • NMR System is tuned
  • Magnet is at full field, persistent mode, leads are ramped down
  • Nose is over 50%, run valve in PID mode
  • Baseline taken and set
  • TE has been taken and new calibration constant feed into PDP
  • Target in correct position along with NHR Channel setting
  • Roughing and Bypass valve open with mechanical pumps on
  • Beam Permit but no beam on target

 

Prepare Frig:

 

  • Ensure Blower 1 interlock light is on
  • Close Roughing valve
  • Turn on Blower 1 and wait 2 minutes
  • Ensure Blower 2 interlock light is on
  • Turn on Blower 2 and wait 2 minutes
  • Ensure Blower 3 interlock light is on
  • Turn on Blower 3
  • Close pump Bypass valve
  • Wait a little while

 

Begin Polarization:

 

  • new Confirm the level in the nose is still around 56%. Set the run valve "man setp" to 0.6 and then the mode to "Man Mode" = YES. Wait for the "Cur Pos" to match the set point of 0.6. (Run valve controls are a pop-up on the cryo-screen, accessed by clicking the button next to "run").
  • Press "TRANSMIT" on the microwave control panel under Control Unit Status (WARNING: Do not touch the button to the right)
  • new Change the mode on the run valve to "Man Mode" = NO.
  • Press "Take Data" on PDP
  • Try to maximize polarization by moving the bellows position
  • Watch the frequency in the top left monitor
  • You can try to start out in the frequency range in the plot of frequency vs Dose since last annel
  • Generally you have to search for the "best" frequency When searching, make changes by 5MHz, 10MHz at the most
  • After making a change, wait about 3 NMR updates to see if it helped/hurt
  • Beam trips will change pol quickly and obscure the effect of your changes especially over 50nA
  • If the frequencies display does not work look also at the poltarcama/Jpeg/CamImgs.jpg using Camera Set 0, use F5 to update (This shows in Hall bellows position)
  • As radiation damage accumulates, frequency will move if polarizing positively, frequency will move down and if polarizing negatively, frequency will move up
  • Use the logbook − see what frequencies worked for other people
  • Log all of your best frequencies when you find them in the Target Operator Microwave Frequency Notebook
  • Tell shift leader you are ready for beam

 

 

 

When it's time to stop polarizing:

 

When the run plan demands you turn off the microwaves (which will never happen during standard data production), we have found that it is necessary to pre-set the run valve setting to prepare the run valve PID loop for the dramatic change in heat load to the target when the microwaves are switched off.

 

  • new Set the run valve "man setp" to 0.1 and then the mode to "Man Mode" = YES. (Run valve controls are a pop-up on the cryo-screen, accessed by clicking the button next to "run").
  • Press "STANDBY" on the microwave control panel under Control Unit Status (WARNING: Do not touch the button to the right on the panel)
  • new Change the mode on the run valve to "Man Mode" = NO.
  • No labels