March 8, 2018 Drift Chamber meeting
- Instructions for Bluejeans meeting connection
- Meeting ID: 290664653
Participants: Naomi (CMU) Eugene, Beni, Alex B., Simon, Alex A., Thomas, and Lubomir (JLab).
- Naomi analyzed the runs from the CDC threshold scan (presentation attached). The number of hits certainly depends on the threshold, mostly pronounced between 90 and 110 (f125 units). The percentage of hits that participate in the tracks (about 30% ) also goes down with the threshold, however this change is relatively small in the 90-140 threshold range.
- The interesting feature Naomi found is that there's a class of events with low amplitudes with a peak in time that is 20ns later than the peak in the drift time for the good hits. Some of these hits end up as part of the tracks, especially at low thresholds, and their theta/z distributions look similar to the ones of the good hits. We had long discussions about the origin of these hits without any conclusion: cross-talk, some kind of e.m.background, electronic noise, reflection at the open end of the straw ... Important is to look at the wave forms of these events (Eugene). Pure electronic noise we can study on the channels that are disconnected from the straws. To study the electronic noise we are also going to take data with the pulser (random trigger).
- Lubomir measured the Oxygen contamination in the CDC with the two sensors both showing very small values, however the sensors need calibration. Also the sniffer showed some higher levels of Ar/CO2 at the sides of the magnet. At the end most likely the sniffer was damaged by the magnetic field so Beni could not use it today.
- Lubomir showed some CDC events from the raw mode run, that were shown before by Sergey, just adding info about the drift time in the x/y plots (attached).
- Not directly related to the tracking: we discussed the 30 J/psi events that are missing in the newest analysis; Thomas finds also 20-50% reduction of the phi's in v7 (and v11) of the the 2016 data analysis, compared to v6. Alex is going to relax the cuts to try to reconcile v6 and v7.
- We were kicked out of the room by the next gluex meeting.