FAQ:Why do I see an extra TDC/ADC hit after large PMT pulses?

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When the PMT has a large pulse, the electronics channel will record two hits. The first hit (TDC ~= 1000) is caused by the PMT pulse. The second hit (TDC~=600) is not a real PMT pulse; it is caused by the oscillation of the tail of the initial PMT pulse. The oscillation is so large that the ADC and 'pedestal' values for this second hit are 0, as seen in the following log file:

MyPrintRawDataAlg                     INFO executing
MyPrintRawDataAlg                     INFO Detector Name: SABAD1
MyPrintRawDataAlg                     INFO Trigger Type: 2052
MyPrintRawDataAlg                     INFO Trigger Number: 0
MyPrintRawDataAlg                     INFO Trigger Time [Seconds part]: 1277705432
MyPrintRawDataAlg                     INFO Trigger Time [Nanoseconds part]: 103498375
MyPrintRawDataAlg                     INFO Full Trigger Time: 1277705432.1
MyPrintRawDataAlg                     INFO Channel ID: detector=SABAD1 board=5 connector=1
MyPrintRawDataAlg                     INFO TDC value: 979
MyPrintRawDataAlg                     INFO TDC value: 638
MyPrintRawDataAlg                     INFO ADC value: 579 (pedestal: 211, peak cycle: 5, gain: 2)
MyPrintRawDataAlg                     INFO ADC value: 0 (pedestal: 0, peak cycle: 0, gain: 1)
MyPrintRawDataAlg                     INFO Channel ID: detector=SABAD1 board=5 connector=2
MyPrintRawDataAlg                     INFO TDC value: 979
MyPrintRawDataAlg                     INFO TDC value: 642
MyPrintRawDataAlg                     INFO ADC value: 631 (pedestal: 208, peak cycle: 5, gain: 2)
MyPrintRawDataAlg                     INFO ADC value: 0 (pedestal: 0, peak cycle: 0, gain: 1)
MyPrintRawDataAlg                     INFO Channel ID: detector=SABAD1 board=5 connector=3
MyPrintRawDataAlg                     INFO TDC value: 980
MyPrintRawDataAlg                     INFO TDC value: 644
MyPrintRawDataAlg                     INFO ADC value: 718 (pedestal: 216, peak cycle: 5, gain: 2)
MyPrintRawDataAlg                     INFO ADC value: 0 (pedestal: 0, peak cycle: 0, gain: 1)
......


The details of this feature is shown on slide 5 of DocDB-5138.

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