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User name brads
Log entry time 14:38:55 on October14,2010
Entry number 334853
keyword=LHRS NMR tricks and tipsIf the LHRS NMR is refusing to lock, you can sometimes encourage it by opening the Dipole NMR controls (Fig 1) from the 'Fields' button on the General Tools screen (Fig 2).
Turn the Search OFF, then type a value into the DAC field and hit return. If you're close, then the NMR will lock. If you're feeling lucky you can turn the search back on and and it _might_ stay locked.
If you are changing the P0 setpoint and lose the NMR lock, you may have to fiddle with this. (Turn search back on, watch the 'scope and GUI readbacks to identify a DAC value that is close to the lock point, then turn the search off, etc.)
The dipole does not seem to drift off the setpoint when the NMR lock goes away, so you should be able to take good data even with an intermittent lock.
A reasonable measure of the dipole stability is the Gaussmeter and dipole current EPICS variables. Feel free to strip chart them as a monitor.
It would be a very good idea to take a snapshot of the Tools and NMR controls screens after each P0 change after you've got the NMR to lock. That way there is a convenient record of the correct NMR readback, current, and DAC value.
Replacement parts have been on order since PREx but haven't arrived yet. We're looking around for other spares onsite.
FIGURE 1
FIGURE 2
