William Angerer - Department of Physics and Astronomy - University ...

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Figure 7.6: Distribution of pulse voltages from photon counting P:\'lT. The wrtical
line represents the discriminator setting. The noise distribution is described by
exponential distribution.
photon is detected. Therefore, we set the discriminator level of the gated photon
counter to a level above the noise but below the pulse amplitude. \Ve determined
the ideal level by measuring the height distribution of the pulses from the P:\IT. :\.
typical pulse height distribution for our PMT is displayed in Fig. 7.6. Thus. the
experimentally determined ideal setting for the discriminator is -30 m \0 for a P:\IT
bias of 1150 V. In addition, we modified the shape of the current pulse to suppress
multiple counting of the same pulse. Typically, a PMT current pulse consisted of
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