- Goal: set the standards for bad/hot channels to be excluded before calibration

- Conclusion:
   a. Judging hot / bad from # of entries or ADC spectra alone looks inappropriate
   b. I suggest at the beginning of the iteration (calibration) exclude only "apparently bad" cases,
        then judge / exclude additional bad channels based on 1st reco. mass along with ADC spectrum

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1. Hot channels

   1-a. Conventional bad/hot channels decision

   - Collected ADC vs. channel by using "physics stream + single MB trigger (st_physics + VPDMB30) ".
   - Saved ADC range: " 3 < ADC < 250 ". To cut out pedestal tail & To see the spectra clearly
   - For the decision, use "# of ADC entries of a cell / # of trigger (left)" and "Each cell's ADC spectrum (right)".

   

   
   
   
   1- b. Complication

   - High online calibration case: a cell with relatively large # of entries does NOT guarantee it's hot.
      i.e. a cell with high online gainCorr -> more frequently triggered, ends up with more entries,
      but it can be properly corrected in offline calibration. Simply masking it out can be dangerous.

   - Possible instability in pedestal subtraction: out pedestal subtraction precision isn't 100 %.
      If a cell has relatively long pedestal tail, it is likely the cell's # of entries will be larger than its vicinity.

   - Channels with high bit shift: if I try to judge hot channels by comparing each ADC spectrum,
     channels with positive (+) bit shift will have relatively larger entries in same ADC bin.

   




2. Bad channels

   2-a. Channels apparently bad

   - Some channels' ADC distribution looks utterly bad. These cells definitely need to be excluded
   - Following plot shows marked "apparently bad" in currently ongoing iteration (Apr. 29)
   - Channels d11_209 and d11_210 were decided bad by independent QA

   
   
   
   
   2-b. Channels with high bit shift >= 4

   - BS = 4 channels in RUN15 day 80-81, ADC (left) and reco. mass (right, ongoing iteration)
   - Cells with gainCorr = 1.0 means they were reintroduced to check if they can be used
   - 10 / 14 look decent to be used

   

   
   

   - BS = 5 channels, in RUN15 day 80-81
   - 11 of 14 look bad