earlier this shift, when we moved back to 15 &181;A beam, Silviu and
I moved from Autogain mode to Forced gain mode on the G0 and G0B BPMS.
These are both in IOC SE20.
The auto gains when running at 1 &181;A were:
X gain Y gain
G0 1851 1847
G0B 1951 1844
(they varied, however, rather rapidly, on the scale of a few seconds).
To set the Gain mode and the gain values, from medm, selected
BPMs, then select "BPM Diagnostics SEE" from the menu. This will
bring up the screen "IPM_E_DiagMenSEE.adl". You can then click
the "Live Displays" button beside the IOC you want to get updating
displays of the gains, etc (this is "IPM_D_LiveDisplay.adl"). To change the
mode and set the forced gain values (or to go back to autogain), select "Expert
Screens" menu, and choose "Gain Control" (this brings up the
"IPM_E_GainCntrl.adl") where you can set the values.
Now, one question we had was this: You can only select one X
gain and one Y gain value for the IOC (i.e. for both
BPMs). Which to pick, or should we pick an average? We decide to
use G0B. Running in Auto gain at 15 µA, and seeing what values
are being chosen, we get XGain =852 and YGain = 813. These are our
"forced" (i.e. fixed to be constant) values. This was used starting
at run 14948.