Difference between revisions of "CDC prototype more on timing"
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[[Image:run_31716_track54_le1_p3_tz6_tfix1_thr5_xchunks2.png|thumb|900px|Ch 20 (straw 17) resolution 2100V thr 5 and 1, tz 6ns, early hits moved to t0+1ns ]] | [[Image:run_31716_track54_le1_p3_tz6_tfix1_thr5_xchunks2.png|thumb|900px|Ch 20 (straw 17) resolution 2100V thr 5 and 1, tz 6ns, early hits moved to t0+1ns ]] | ||
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[[Image:run_31716_track54_le1_p3_tz6_tfix1_thr5_xchunks3.png|thumb|900px|Ch 20 (straw 17) resolution 2100V thr 5 and 1, tz 6ns, early hits moved to t0+1ns ]] | [[Image:run_31716_track54_le1_p3_tz6_tfix1_thr5_xchunks3.png|thumb|900px|Ch 20 (straw 17) resolution 2100V thr 5 and 1, tz 6ns, early hits moved to t0+1ns ]] | ||
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Revision as of 14:30, 24 October 2011
Current analysis code procedure:
- Calculate s.d. of pedestal for first 100 samples, 100 events, save for later use (sigma)
For each event...
- Calculate mean pedestal over 100 samples ending 10 samples before the trigger time (every 4th of these samples also works)
- Search forward for sample x where adc value > high threshold n1 sigma
- Step back p samples to sample x-p, take adc value of sample x-p to be local pedestal value
- Subtract local pedestal value from a number (10+p) of samples starting at sample x-(p+5) to the LE algo for unsampling
- Search through unsampled data, start with last sample (highest adc value) search backwards until adc value < low threshold n2 sigma
- Calculate time where interpolated unsampled data cross n2 sigma, and add to time of sample x-p, this is the estimated drift time.
Unsampled adc values (z) using different values for p (local pedestal lead time ahead of first/high threshold crossing) for high threshold of 5 sigma. x-axis=0 corresponds to sample x-p-4.2, x-xaxis=5 corresponds to 1+x-p-4.2, etc. 5 unsampled values per 8ns sample, all events for ch17 (central straw) included (no tracking)
High threshold 4 sigma
High threshold 6 sigma
Previous best resolutions for 50/50 gas mix using single threshold of 4sigma:
Resolutions for ch20 ignoring hits before tzero, using 50/50 mix in Garfield and wire diameter of 17.8um instead of 20um, 2100V (left) and 2050V (right).
Current best resolutions for 50/50 gas mix and 17.8um wire, using high threshold 5sigma followed by low threshold 1sigma, p=3
Ignoring hits before tzero (tzero = fitted value + dt, dt=6ns)
Moving early hits to tzero+1ns
