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User name brads
Log entry time 09:28:53 on October16,2010
Entry number 335133
This entry is a followup to: 335119
keyword=LHRS dipole at 2.607 and NMR locked (HowTo instructions)I got the Dipole NMR to lock by finding an earlier halog entry 334960 that had snapshots fo the NMR and General Tools screen.
With regulation off, I typed in the current for 2.607 GeV/c into the dipole power supply control (~899.04A from the old entry). Once the supply settled I could verify that the gaussmeter readback was very close to the 0.92950 from the old halog entry.
Next I got to the NMR screen, disabled search and typed in the DAC value that would get the NMR close to resonance (1335 in this case, taked from the old log entry). I also switched to probe B, that seems to be a little more stable at this momentum. I can verify that that is pretty close by watching the D-N field readback and seeing that it gets close to the expected value of 0.9645685 with that DAC setting. After a short wait the NMR found a lock and I got a valid readback from the system.
In a pinch we could call it a day here and be done. As long as the field is stable (ie. the P0 value is green and/or watch the D-G field if the NMR looses lock) you're fine to take data. But let's get the regulation back on anyway.
I turn the search back on in the NMR screen. If you're lucky it'll stay locked, if it walks off into nowhere try being patient to see if it relocks, or turn search off, type in the correct DAC value, and try again.
I open the regulation screen (button to left of the P0 SET field in HA Tools) and re-enable the regulation. I observe that the current walks up to high values and the NMR looses lock and doesn't find it again. I turn off regulation, type in a dipole current that is a bit lower than the target, fiddle with the NMR to get a lock, turn regulation back on and it walked the current up into the correct value where it stabilized.
YMMV.
FIGURE 1
FIGURE 2
