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User name X. Zheng
Log entry time 10:37:39 on November 20, 2009
Entry number 301304
This entry is a followup to: 301240
Followups:
keyword=Right arm pion narrow group problem could be due to scaler problem rather than noiseI don't think the pion problem is from noise: noise should not occur only in one helicity. The asymmetry plot clearly shows two peaks, which indicate that for some events the hel+ scaler reading is significantly larger than hel-, and for some events the opposite. This does not look like noise.
(asymmetry plots: www.jlab.org/~adaq/pvdis/slug_output/)
If you take the average count per helicity pair, times the asymmetries of
the two peaks, that gives a shift in count of ~160 for all three groups
of narrow pion channels. This means, for some helicity pairs, hel+ events
have a shift of +160, some pairs have hel- events shifted by +160. The
fact that this shift is the same for all three groups is another proof
it's a scaler. The estimate of the shift is very rough so the actual
shift could be different.
A copy of this log entry has been emailed to: rom,pkpan,dwang,rsubedi,deng
Figure 1 Pion average rate
Figure 2 Pion asymmetries
