[Vetroc_daq_sbs] Status

[R. Evan McClellan]

Everything is back to normal and working properly. Here are a few discoveries:

1 - I am an idiot. My "minimal" decoder had been decoding the same .dat file, regardless of the run number command line argument. This is now fixed. This was the cause of my confusion about the reference channel timing not changing when cable lengths were changed.

2 - THE DISPLAY ON THE PULSER IS UNTRUSTWORTHY. When changing the "high level" and "low level" of the channel A output, we noticed that the numbers on the display were often different that the buttons we were pressing. Checking the output on the scope, we found that the actual output matches the buttons we pressed, NOT the displayed number.
(e.g. try entering 0V for the low level. The display will show 2.0V, but the actual low level of the output is 0.0V)

3 - Setting the pulser period too short will cause the system to not see any triggers. I suspect that this is due to the GTP using 32ns wide bins internally. However, we did not fully investigate this issue. Setting the period to 250 us works fine.

After noticing #2 and #3 above, we tried to find settings on the pulser which produced the best-looking PMT pulses. We arrive at LOL = 0.0V, HIL = 0.8V, WID = 9ns.

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Next steps:
- Modify event-display to read class-based event format (Evan, Scott)
- Connect some signals to ADC, try taking some runs, check raw data, attempt to time-in analogue signals
- modify minimal decoder to handle ADC data
- test out "time-over-threshold" gain-matching idea
- Think about most useful way to store raw data (hit time & length rather than rising edge and falling edge times?, etc.)

Cheers,
Evan


R. Evan McClellan, PhD
Hall A Postdoctoral Fellow
Jefferson Lab