CDC Pedestal Studies

Pedestal Subtraction

Based on cosmic ray data with BCAL trigger Look for events with the following signature in the CDC:

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The first test was done by using the region $P_{{i}}$ (blue) to determine a pedestal and the region I (red) to determine an Integral and then subtract the proper pedestal from the Intergral as follows: $D=I-P_{{i}}/N_{{i}}*80.$ where $N_{{i}}$ is the number of samples used to calculate the pedestal and 80 is the number of samples in the Integral I. In the case of no signal the the distribution D is expected to be around zero with a sigma that reflects the resolution and depends on the number samples $N_{{i}}$ used in determining the pedestal. As an example the distribution with 4 samples in the pedestal calculation looks like this:

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$N_{{i}}$	mean F	sigma F	mean I	sigma I
4	102.2	1293	96.5	1276
16	119.0	1121	163.4	1120
20	121.1	1080	145.1	1080
32	102.4	984	159.0	978
64	40.9	680	84.6	685

Looking just at the pedestals you get the expected results like here, a pedestal determined over the first 16 samples:

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