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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.
    Short summary:
    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.

    Some details:
    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.