User name Armstrong
Log entry time 17:54:17 on June24,2001
Entry number 64429
Followups:
- 64457 06/24/01 21:45 Armstrong suggestion read asymmetry feedback
- 64472 06/24/01 23:41 Armstrong beam oscillations gone?
I have looked at "apar" (the Parity-DAQ-based analysis of beam charge
asymmetry) for the last 8 runs (i.e. the last 8 hours or so) and find that
the following behaviour is present for each run:
- the beam current oscillates roughly sinusoidally, with a period of
about 30 minutes, and an amplitude of about 3% of the average current.
- the beam charge asymmetry oscillates in a completely correlated
manner, with an amplitude of about 250 ppm.
This looks to me like something the injector group should be alerted
to. Possibly thermal fluctuations? Note that our feedback, based on
averaging a roughly hour-long run, will average over this only if we
have a run that matches two oscillations in length (rather reminiscent
of the 30 Hz helicity-flip to average over 60 Hz noise)....
Plots from a typical run (run 933) are shown below; so far, all the
runs I have looked at recently (932-939) show the same pattern...
FIGURE 1
