TDC histograms

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To test the time resolution of the setup, we placed the trigger at different positions and recorded the time it took for a cosmic ray to produce a signal. We then fit the data with a Gaussian fit. Two types of discriminators were used: a Leading Edge Discriminator (LED) and a Constant Fraction Discriminator (CFD). An LED produces a signal once a certain threshold is surpassed while a CFD produces a signal once a specified fraction of the input signal has been reached. The unit of time in the histograms is 56 ps, which means that multiplying an X-value in the histogram by 56 ps will yield the actual time.

Varying widths of the trigger pedal were used. A wider trigger pedal will produce signals more quickly but at the cost of time resolution. A thinner trigger pedal takes longer to produce a signal but will improve time resolution.

Different models of photomultipliers were used.