Minutes-11-19-2015
November 19, 2015 Drift Chamber meeting
Connection
- Instructions for Bluejeans meeting connection
- Meeting ID: 290664653
- To join via a Web Browser, go to the page [1] https://bluejeans.com/290664653.
Agenda
- CDC update (Mike, Simon)
- FDC update (Lubomir, Luke)
- New resolution results: [2], cathode resolution,wire resolution, residuals
- plan for TRD studies
- Electronics (Fernando, Chris, Nick)
- Response Function of preamp+cable+fADC125: FDC 200fC, CDC 500fC, FDC/CDC Max and Min, FDC and CDC Max/Min ratio
- Response Function of preamp+cable: FDC
- Engineering (Dave)
- templates for CDC and FDC NIM papers
- Other
Minutes
Participants: Curtis, Naomi, Mike (CMU), Sean (NU), Cody, Luke, Dave, Chris, Nick, Simon, Beni, and Lubomir (JLab).
CDC update
- Nick found the broken wire and separated it from the HVB (see log entry above). He fixed one more channel by replacing the HVB card.
- Mike is looking now at the beam data; will apply the same correction as with the cosmics to correct for the tube sagging.
FDC update
- Lubomir showed latest results on the resolution studies. The resolutions improved gradually due to some residual corrections, better alignment, tracking and finally by using Mathieson/Simon's function when fitting strip clusters: first plot shows the different functions
Electronics
- Lubomir and Luke measured the response function of the FDC preamp-cable-fADC125 system using the DAQ in the tagger. We used a charge injector at the input - step function from pulse generator on 1pC capacitor on a board that Fernando used before. All the millivolts in the above plots correspond to the step amplitude. We first looked with a scope and found that the peak and tail-cancellation parts saturate in different way (first two plots) - Fernando says that's normal.
- The last plot shows summary of the measurements with fADC125: the max (red) and min (blue, absolute value) of the response function for different input charges. The range with good linearity of the max is narrower that that range for the tail-cancellation part (the minimum). Thus, the poor dE/dx resolution of the FDC can be explained by saturation effects present already at ~2000 units, i.e. half of the fADC125 range. The undershooting is about 20-25% of the peak amplitude. Looking and the Naomi's result for the CDC pre-amp we see that there the tail-cancellation is only about 10%. This might be an explanation for the ion tails seen in the CDC. We will repeat the measurement with a CDC pre-amp.
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