Difference between revisions of "CDC prototype more on timing 3"

Revision as of 15:20, 20 March 2012

Latest approach to hit finding is as follows:

Find a hit channel and event pedestal
1. Calculate mean pedestal P_m & s.d. (σ) for first 100 samples in 100 events (trigger is approx sample 200)
2. Set a threshold T_p (eg 3.5 σ) for further investigation, eg P_m + T_p , select events & channels where adc value exceeds this
3. Calculate event pedestal P_evt as mean of samples 90 to 190 in current event
4. Select events where adc value goes over high threshold T_h1 + P_evt (T_h1 ~ 5sigma)
Find high threshold time and new local pedestal
1. Upsample data from samples 150 to 350 (max drift time + trigger time is approx sample 290)
2. Search forward to find point x1 where data goes above a not quite so high threshold T_h2 + P_{e} where T_h2 ~ 4 σ
3. Find a local pedestal P_loc as adc value at N_p upsampled points before x1 (eg N_p=15)
Find low threshold time and new local pedestal
1. Search backward from x1 to find point x2 where data goes below low threshold T_h2 + P_loc where T_h2 ~ σ

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 ## Calculate event pedestal P<sub>evt</sub> as mean of samples 90 to 190 in current event
 ## Select events where adc value goes over high threshold T<sub>h1</sub> + P<sub>evt</sub> (T<sub>h1</sub> ~ 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 T<sub>h2</sub> + P_{e}  where T<sub>h2</sub> ~ 4 &sigma;
 ## Find a local pedestal P<sub>loc</sub> as adc value at N<sub>p</sub> upsampled points before x1 (eg N<sub>p</sub>=15)
 # Find low threshold time and new local pedestal
 ## Search backward from x1 to find point x2 where data goes below low threshold T<sub>h2</sub> + P<sub>loc</sub>  where T<sub>h2</sub> ~ &sigma;