MD9NEG must have gotten turned on again although there was no hclog entry. As a reminder, during N to Delta operations, the background detectors all see elastic radiative tail and/or window scraping.
The MD9NEG ADC input must have been .geq. 15V for days. I suspect neither the ADC nor the preamp can be damaged by this. However, the anode current might have been 10's of muA's, permanently reducing the gain of the PMT. We've got a lot of headroom though, so if needed, we should be able to simply increase the HV. It's not worth turning off at this point; it's water under the bridge. But it will be interesting to see if the yield (V/muA) recovers to its old value when we go back to elastic operations.