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Drift Time study from Cosmic data

General description of the plots

The study of the 32-sample physics pulses of cosmic events allow us to study the Drift Time in the Liquid Argon. The undershoot of the pulse is related to the Drift Time and the rising at the end of the pulse is sensitive to a shift of the electrode with respect to its nominal central positioning. These two parameters are let free, as well as the global normalization and time adjustement, in the fit of the pulse (using the FPM method for prediction). Events from cosmic data taken during MCalo and M7 weeks, and triggered by L1Calo, are analyzed. Details on the method used are available in Caroline Collard's presentation during July 2008 LAr week.

Drift Time vs abs(eta)

This plot shows the Drift Time extracted from the fit as a function of |Eta|, only for the Middle compartment of the Barrel part of the calorimeter. The black dots represent the mean values (from a gaussian fit) per Eta bin. To do these plots, ~40000 cells are used. The color axis represents the number of "reweighted" entries per bin ["reweighted" to give more weight to events with smaller fit error on the drift time parameter, but keeping the global number of entries constant].

Drift Time vs eta

This plos is the same as above, but as a function of Eta. In addition, the grey line is shown which represents the prediction from absorber thickness measurements [A serie of one absorbed, one gap, one electrode and another gap is a fixed pitch. Any variation in the absorber thickness in one direction will imply a gap variation in the opposite direction and thus a variation of the Drift Time because this last one is directly related to the gap size].


Major updates:
-- IsaWingerter - 21 Oct 2008

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Topic revision: r4 - 2008-10-23 - StephenHaywood
 
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