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User name V. Sulkosky
Log entry time 23:04:43 on January 16, 2009
Entry number 256402
keyword=Re: Left Gas CerenkovI looked closer at the "new peak" in the Gas Cerenkov ADC sum. Figure 1
shows the ADC sum for run 5195 with and without a cut on the Cerenkov
TDC. For this cut, I only required that there be a hit (time > 0). With
this cut, the peak goes away.
First the true single photo-electron for the calibrated GC is at channel
200. This other peak is centered at 266 channels.
In the second figure, I have plotted the same histograms as Figure 1 but
for run 5177, which was before this additional peak showed up. Here the
TDC cut mostly removes the pedestal, which is expected.
In the third figure, I have plotted the ADC sum for run 5177 and 5195
with the TDC cut. The spectra for the two runs with this cut match very
well with each other. This indicates that the events in this peak are
not good events. There is no hit in the TDC for them. This seems to
indicate that there is some additional noise in the system perhaps in
ROC 3. We have noticed a few other symptoms in the HRS since yesterday
as well.
A copy of this log entry has been emailed to: jiang,jpchen,xqian,ycwang
Run 5195
Run 5177
Runs 5177 and 5195
