Difference between revisions of "CDC prototype more on timing 3"
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## Calculate mean pedestal P<sub>m</sub> & s.d. (σ) for first 100 samples in 100 events (trigger is approx sample 200) | ## Calculate mean pedestal P<sub>m</sub> & s.d. (σ) for first 100 samples in 100 events (trigger is approx sample 200) | ||
## Set a threshold T<sub>pm</sub> (eg 3.5 σ) for further investigation, eg P<sub>m</sub> + T<sub>pm</sub> , select events & channels where adc value exceeds this | ## Set a threshold T<sub>pm</sub> (eg 3.5 σ) for further investigation, eg P<sub>m</sub> + T<sub>pm</sub> , select events & channels where adc value exceeds this | ||
− | ## Calculate event pedestal P<sub>evt</sub> as mean of samples | + | ## Calculate event pedestal P<sub>evt</sub> 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 | # 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) | ## Upsample data from samples 150 to 350 (max drift time + trigger time is approx sample 290) |
Revision as of 09:24, 26 March 2012
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 Tpm (eg 3.5 σ) for further investigation, eg Pm + Tpm , select events & channels where adc value exceeds this
- 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: