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    User name Saha

    Log entry time 12:24:03 on October 29,1998

    Entry number 4036

    Followups:

    keyword=BCM Calibration Results

    I have analysed all the past BCM calibration data for the current experiment 94010. There were two phases to the experiment. In the first phase (Sept 26-Oct 4), the downstream BCM cavity was not tuned, (its output was a factor 10 down) and only the upstream BCM cavity was near tune. We named the working BCM cavity "BCM2" for reasons which are too elaborate to mention here. In any case its calibration coefficient are stated here:

    BCM 2 Phase 1 (Sept26-Oct4)

    Sept 26 STD-40 HAC-1220 29.007 +/- 0.186
    Sept 26 STD-40 ACC-1555 28.962 +/- 0.213
    Sept 26 Step-Wt ACC-1516 28.763 +/- 0.397
    Sept 28 STD-30 HAC-1376 28.926 +/- 0.282
    Oct 3 STD-45 HAC-1495 28.841 +/- 0.176
    Oct 4 STD-45 HAC-100498 28.815 +/- 0.152

    Weighted Mean = 28.889 +/- 0.083

    After Oct 9, we had both cavities retuned, and working fine. The results:

    BCM1 BCM2
    Oct 9 HAC-1644 31.895 +/- 0.292 29.245 +/- 0.267
    Oct 12 ACC-1505 31.876 +/- 0.469 29.212 +/- 0.430
    Oct 13 HAC-1750 32.049 +/- 0.271 29.358 +/- 0.248
    Oct 18 HAC-1868-1 31.969 +/- 0.333 29.314 +/- 0.327
    HAC-1868-2 31.784 +/- 0.295 29.111 +/- 0.286
    HAC-1868-3 31.719 +/- 0.373 29.070 +/- 0.342
    Oct 23 HAC-1916 32.020 +/- 0.199 29.327 +/- 0.182
    1023-0400 31.785 +/- 0.277 29.136 +/- 0.255
    1023-0523 31.729 +/- 0.278 29.129 +/- 0.256
    Oct 27 HAC-2072 31.800 +/- 0.243 29.178 +/- 0.223
    HAC-2070 31.929 +/- 0.459 29.290 +/- 0.412

    Weighted Means: 31.882 +/- 0.088 29.226 +/- 0.081

    From the results, one sees that the cavities once tuned are very stable (<1%). We still need to perform the calibration maybe once a day to check this. I shall now change the calibration coefficients in the BCM calibration screen to the present values so that the screen shows the true current to Hall A. The old values are close (BCM1: 31.482, BCM2: 28.863) and changed to (BCM1:31.882, BCM2:29.226).