|The noise contribution is minimised by selecting an
appropriate amplifier shaping time constant.
At short time constants the series noise component is dominant and at
longer time constants the parallel noise is more significant. Therefore
optimum shaping is achieved where series and parallel noise are equal.
If the amplifier shaping is much shorter than the time taken to collect
the generated charge then ballistic deficit occurs. It is observed in the
spectrum as a pronounced tailing at the low energy side of the peak.
the shaping time control in the simulation. You should detect a
slight increase in the noise level at lower levels.