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User name jroche
Log entry time 18:14:02 on October 26, 2010
Entry number 336838
This entry is a followup to: 334870
keyword=BCM calibration: some result.
Here are some results from the BCM calibration we did on 10-14.
We should use the BCM entries multiplied by a factor 3 for current
ranging from 1 to 10 uA. This should give us a 0.5% measurement of the
charge. I still have a few steps to go through before implementing the
calibration in the analysis code. Please read and feel free to comment.
When we did take the data, the 1024 Hz clock was double counting so I
used the 103.7 kHz clock as a time normalizer. All results are relative
to the 103.7 kHz clock.
First I extracted the beam current measured in the injector (Faraday cup
and OLO2 readings) from BcmLog_159 and BCMLog_160. I did correlate the
beam on-off period with data in coda file 7353 and 7354 and extracted the
corresponding slope of the scaler reading Hall A bcms (u1,u3,u10, d,1,d3
and d10). These results are in text file first_cal.txt.
Then I fitted the hall bcms against the readings of OLO2 in various
ranges: 50->2 uA for u1 and d1, 10->1 ua for u3 and d3 and finally 5->0.5
uA for u1 and d10. Finally, I computed residuals and concluded that we
should be ok using u3 and d3 in the range of 1 to 10 uA. In that range,
the calibration should be ok within a 0.5% precision.
Data file with OLO2 readings versus Hall A bcm slopes
Fits of the radings
Residuals of the fit zoomed between 0 and 12 uA
Residual of the fit between 0 and 100 uA
Text file of the residuals.