The 3-4 HAPPEX runs afterwards showed that the electron narrow triggers for gr5-8 had a 200Hz rate in the scaler reading, while wide triggers are still 100Hz. Note that our tagger is 100Hz for the whole period, and the physics electron trigger rate should be very low.
After the beam went down, I went to check why the rate is doubled, and found the DH and DM outputs have double- or triple- pulsing because the thresholds are too low and the tagger input has multiple after-pulsings (small peaks that trigger the discriminators). As a result, the coincidence output between electron narrow or wide triggers and the delayed tagger also have double-peaks in about half of the groups.
I just changed (14:30) the DH and DM thresholds to -105mV and -25mV to
avoid the multiple pulsing problem. We will run with higher thresholds
for the production run anyway.
A copy of this log entry has been emailed to: rsubedi@jlab.org,dwang@jlab.org