Simple digitization module which translates the collected charges into a digitized signal proportional to the input charge. It simulates noise contributions from the readout electronics as Gaussian noise and allows for a configurable threshold. Furthermore, the linear response of an QDC as well as a TDC with configurable resolution can be simulated.
For maximum simplicity only the absolute of the charge is used and compared to a positive threshold.
In detail, the following steps are performed for every pixel charge:
By default, this module operates only on channels which have received a pixel charge. This means, noise and threshold are only applied where there was a signal, but not in channels where no signal was present, and also not in events where no
interaction with the sensor material has occurred. In many situations, this is the desired behavior since the threshold is configured such that it is unlikely to be crossed just from a pure noise contribution.
Front-ends are often configured with a threshold equal or higher than five sigma of the noise.
There are situations, however, where a sampling of *all channels* is desired, and where also the noise contribution is relevant. In this case, the parameter `sample_all_channels` can be set to `true`.
The module then calculates the noise contribution for all channels of the detector, applies the threshold and passes on all hits crossing the threshold.
This is also performed in events without any particle interaction in order to obtain a reasonable signal-to-noise ratio.
It should be noted that this procedure can significantly slow down the simulation for detectors with high granularity or millions of channels.
According to the above setting, the following steps are performed either for every pixel charge or for every pixel of the detector:
* A Gaussian noise is added to the input charge value in order to simulate input noise to the preamplifier circuit.
* The preamplifier is simulated by applying a gain function to the input charge, or by multiplying the input charge with a defined gain factor.
