Make New Entry, Make Followup Entry
User name V. Sulkosky
Log entry time 15:05:40 on November 07, 2008
Entry number 247362
This entry is a followup to: 247361
keyword=BPM and Raster Work IIFrom the previous entry, after the gate change, the raster was clipping
at the low end of the ADC spectra. I adjusted the offsets and increased
the voltage after the attenuator from -40 mV to -130 mV. The raster size
we were using was 3 mm x 3 mm. I figured that we might want to go to
4 x 4 or even 5 x 5. So I left enough room to prevent this problem from
happening for those sizes. Figure 1 shows the raster X current versus
raster Y current with the new settings.
Then with Elaine's assistance, we adjusted the attenuator settings for
the BPM readouts. First we looked at the baseline from the electronics
without beam. Then we used a 1.5 V battery to simulate beam conditions
to fine tune the settings. I set the attenuators so that the BPM
antenna signals were roughly at 1500 channels in the ADC. From past
experience, this was close to channel 2000 prior to Transversity. I
found the settings to get about 1500 channels was -49.5 mV.
Figure 2 shows the BPM raw antenna signals from run 2982. During this
run Elaine connected a 1.3 volt battery to all eight cables going to the
HRS to check simulated beam conditions to ensure we do not saturate with
beam. These periods are the high values in the plots on the y-axis.
A copy of this log entry has been emailed to: brads,camsonne,rom
Figure 1
Figure 2
