[Halld-tagger] TAGH analysis update

[Nathan Sparks]

Hi Richard,

Sorry about missing the meeting earlier. I made an early escape for Thanksgiving!

I just wanted to mention that I am working on the tagger hodoscope data analysis, but have so far just quickly looked at those first calibration run data that Sasha collected. At the moment the TAGHHit data is very noisy and many of the monitoring histograms do not make much sense. The first thing I noticed is that the hit occupancy plot is flat instead of rising with counter number, which one expects from the (1/k) bremsstrahlung distribution. I found that if I filtered the hits by requiring at least 15 ADC counts (after subtracting the pedestal) that the expected shape of the occupancy plot was obtained (it matches the dist. that Sasha showed in the log). Another matter is that the (TAGHHit) timing histogram just shows a spike at zero, coming from the fact that the hit algorithm is not able to match fADC and TDC times, and the default value of zero gets filled. I also looked at a histogram of the ADC/TDC time difference and it was completely flat. Apparently the TDC time offsets are out of whack, as was mentioned by Beni in the run coordination meeting this morning.

I made a few changes to DTAGHHit_factory.cc
1. There was an incorrect column name used for accessing ccdb data. This was causing incorrect data (zeros) for calibration data to be read in. The correct counter column name for these data is “id”, not “counter” (as in the scaled_energy_range table).
2. The pedestal was changed to account for the number of samples, and duplicate scaling factor (nsamples_integral) removed.
3. Moved counter-quality continue statement to beginning of loop, before pointers to TAGHHit objects are created.
4. Correct a typo in the calculation of fadc_time. TDC time offset was being used instead of the ADC one.

Items 2-4 probably need to be applied to DTAGMHit_factory.cc as well.

Best regards,
-Nathan