Since the 1881 is a 12 bit ADC that bin is at the upper end of its acceptance (0--4095). Overflows also typically get stuffed into this bin by the module but it looks like the analyzer (Cerenkov class, I assume) uses it for additional bookkeeping.
The Cerenkov class can certainly be modified to use a different channel
for its book-keeping (and I think that is a good idea).
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