User name paschke
Log entry time 17:05:23 on July16,2003
Entry number 104075
keyword=Hall C beam effect on Hall A beam
This afternoon G0 performed parasitic tests with source elements directly effecting
only the Hall C beam (IA/PZT scans). As agreed, we monitored the effects in
Hall A. It appears that a very large fraction of the effect seen on the Hall C beam
was seen on the Hall A beam.
Figure 1 is from parity DAQ run 3305, between 14:00-15:00 this afternoon. It is
unclear exactly which portion of the G0 studies this represents: probably one of the
PZT scans. The three evident values of charge asymmetry represent the
two extreme and middle setpoint for the PZT setpoint. The apparent slope is
approx. 675 ppm/Volt.
G0 records a charge asymmetry slope of 740 ppm/Volt for the PZT scan. If fig. 1
shows the PZT -X scan (and not PZT-Y, for which we don't yet have results
from G0) this would suggest that the effect on the Hall A beam is 90% of the effect
on the Hall C beam!
Hall A was running near 2-3 uA, and Hall C at 90 uA. Was 90% of the
Hall A beam coming as bleedthrough from Hall C? If not, other effects (like
cathode loading?) may need to be considered.
Also: the magnitude of charge asymmetry I quote here is sensitive to the BCM
pedestal, which has not yet been calibrated. Hopefully we can use the lumi (or the
BCM calibration procedure to be performed in the next couple of days?) to check