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User name johna
Log entry time 20:29:37 on November28,2009
Entry number 303373
Followups:
keyword=Bad BCM readout in end of run files
Noticed that we were getting crazy readings in the BCM output from the end of run files. The different gains were giving wildly different results, and there was a strong run-to-run variation.
On the scalars screen, they seem to be alright (0 counts during trips to 200-250kHz or 800-1000kHz at 100uA, depending on the signal), except for bcm_u1 which is getting 0 counts. Looks like the x1 BCMs are around 250kHz, and the x3 are (roughly) 3 times that, and the x10 are just a little larger, so probably off scale at these currents, which I guess isn't really that surprising.
Could just be that the calibation numbers being used for this aren't right, although the run-to-run variation would suggest something else, e.g. scalars not being cleared between runs, although i would expect even wilder fluctuations in that case. Below are some end of run outputs (the 3 L-HRS runs correspond to the 3 R-HRS runs). Even ignoring the x10, which are presumably off scale, there is roughly a factor of two difference between the left and right arm values for the x1 readout, and the x3 readout is really messed up for the most recent run.
25858 x1=97uA, x3=-76uA, x10=-7.8uA
25857 x1=96uA, x3= 94uA, x10=-32uA
...
25835 x1=108uA, x3=106uA, x10=51uA
5405 x1=48uA, x3=-76uA, x10=-8uA
5404 x1=48uA, x3=94uA, x10=-32uA
...
5392 x1=54uA, x3=108uA, x10=51uA