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Signal-to-Noise:
This is defined as the ratio of the separation of the signal from
the pedestal, to the sigma of the pedestal. The first plot contains 1-strip
clusters, where one strip had a signal greater than 2.5x the pedestal sigma,
as well as 2-strip clusters, where two neighboring strips had signals greater
than 2x the pedestal sigma. In addition, a coincidence with a signal on the
downstream silicon detector was required.
It shows the expected landau distribution of the
deposited charge, as well as the upper edge of the pedestal.
The lower plot was generated using much stricter cuts. Only 1-strip clusters that had signals greater than 2.5x the pedestal sigma, and whose neighbors were lower than 1.5 this sigma, and who met the downstream coincidence requirement were included. This created a cleaner landau distribution without the pedestal edge. The maxima in both distributions are located roughly in ADC channel 60. With a pedestal sigma of 10, this gives a signal-to-noise of 6:1. Note that in the next prototype, the noise will be greatly reduced, and the pedestal width is expected to be only a few channels. |