2009.11.20 - Fitting Cbar22 with BPM Tilts (actual data)
Today's machine conditions:
- 2.085GeV, e+ injection set (POSINJ)
- Phase/coupling corrected
- Use phase.08332 to fit BPM tilts
Fit Cbar22+12 data using the newly developed technique:
- Use cbar12, fit using skew quads and vert steerings
- Fit cbar22+12 using bpm_tilts
Do not use cbar11 data yet, as it looks much worse than cbar22 data
for now. Track the RMS cbars to see how things are affected during the
fit:
| Cbar ele |
Initial |
Fit sk_quad, vert |
Fit bpm_tilt |
| cbar22 |
0.026 |
0.024 |
0.000 |
| cbar12 |
0.010 |
0.002 |
0.002 |
| cbar11 |
0.931 |
0.933 |
0.939 |
Although the RMS Cbar11 actually got -worse- after fitting, I'm not
sure that data is believable to begin with. See fitted tilts here. RMS fitted tilts =
20.34mrad.
A few comments:
- JSx's survey suggests RMS BPM tilts should be ~6mrad
- On 2009.11.17 we looked
at the effects of residual (uncorrected) Cbar12 on the quality of BPM
tilt fits. On that plot, an uncorrected RMS Cbar12 of 0.002 (as we
have here) will give us an RMS BPM tilt difference (applied - CESRv
fit) of ~8.5mrad. Keeping this in mind, our tilts COULD be as small as
~12mrad from this fit, if we could beat down the residual Cbar12 below
0.002.
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