CDC prototype more on timing 3
From GlueXWiki
Latest approach to hit finding is as follows:
- Find a hit channel and filter events
- Calculate mean pedestal Pm & s.d. (σ) for first 100 samples in 100 events (trigger is approx sample 200)
- Set a threshold Tpm (eg 3.5 σ) for further investigation, eg Pm + Tpm , select events & channels where adc value exceeds this
- Calculate event pedestal
- Calculate event pedestal Pevt for current event & channel, as mean of 100 samples ending 10 samples before trigger time
- Use event pedestal to find high threshold time and new local pedestal
- Upsample data from samples 150 to 350 (max drift time + trigger time is approx sample 290)
- Select events where adc value goes over a high threshold Tpe + Pevt at point x (Tpe ~ 5sigma))
- Find a local pedestal Ploc as adc value at Np upsampled points (minisamples) before x (eg Np=15)
- Use local pedestal to find high and low threshold times
- Search forward from x-Np to find point x1 where data goes over a slightly less high threshold Th + Ploc where Th ~ 4 σ
- Search backward from x1 to find point x2 where data goes below low threshold Tl + Ploc where Tl ~ σ
To find where to take local pedestal:
