CDC prototype more on timing 3
From GlueXWiki
Latest approach to hit finding is as follows:
- Find a hit channel and event pedestal
- Calculate mean pedestal Pm & s.d. (σ) for first 100 samples in 100 events (trigger is approx sample 200)
- Set a threshold Tp (eg 3.5 σ) for further investigation, eg Pm + Tp , select events & channels where adc value exceeds this
- Calculate event pedestal Pevt as mean of samples 90 to 190 in current event
- Select events where adc value goes over high threshold Th1 + Pevt (Th1 ~ 5sigma)
- Find high threshold time and new local pedestal
- Upsample data from samples 150 to 350 (max drift time + trigger time is approx sample 290)
- Search forward to find point x1 where data goes above a not quite so high threshold Th2 + P_{e} where Th2 ~ 4 σ
- Find a local pedestal Ploc as adc value at Np upsampled points before x1 (eg Np=15)
- Find low threshold time and new local pedestal
- Search backward from x1 to find point x2 where data goes below low threshold Th2 + Ploc where Th2 ~ σ