CDC prototype more on timing 3

From GlueXWiki
Revision as of 15:20, 20 March 2012 by Nsjarvis (Talk | contribs)

Jump to: navigation, search

Latest approach to hit finding is as follows:

  1. Find a hit channel and event pedestal
    1. Calculate mean pedestal Pm & s.d. (σ) for first 100 samples in 100 events (trigger is approx sample 200)
    2. Set a threshold Tp (eg 3.5 σ) for further investigation, eg Pm + Tp , select events & channels where adc value exceeds this
    3. Calculate event pedestal Pevt as mean of samples 90 to 190 in current event
    4. Select events where adc value goes over high threshold Th1 + Pevt (Th1 ~ 5sigma)
  1. 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 Th2 + P_{e} where Th2 ~ 4 σ
    3. Find a local pedestal Ploc as adc value at Np upsampled points before x1 (eg Np=15)
  1. Find low threshold time and new local pedestal
    1. Search backward from x1 to find point x2 where data goes below low threshold Th2 + Ploc where Th2 ~ σ