Digitization

In ratpac-two, the user has the option to digitize waveforms for each photodetector channel according to a set of user defined settings. The settings are specified in DIGITIZER.ratdb and are separated for different digitizer types. Settings for two common CAEN digitizers, the V1730 and V1742, are provided as examples.

The digitization of PMT pulses is triggered by certain DAQ code once the specified conditions are met. As an example, the forcedtrigger processor, described in more detail in DAQ Models, will digitize hit channels for every MC event, given that the value in the appropriate DAQ.ratdb table is specified as: digitize: True. Also specified in the DAQ.ratdb table is which type of digitizer to select (e.g., V1730 or V1742), with V1730 being the typical default model.

When the digitization is enabled, a PMT pulse will be generated for every mcPE, detailed in PMT Pulse Generation. A fixed window is selected and the PMT pulse, with Gaussian noise added, is sampled across that window. The voltage (or ADC counts) as a function of time (in steps according to the sampling rate) is used to create a digitized waveform for each PMT. This waveform is written to the DS::Digit object. The waveforms can also be added to the ntuple output by setting include_digitizerwaveforms: true in IO.ratdb.

These waveforms can be further processed in ratpac-two in order to produce additional information, such as the integrated charge or the time-over-threshold, by applying the waveform analysis. The waveform analysis will open the DS::Digit to extract the waveforms and will process those waveforms according to user-specified criteria. The output of the waveform analysis will fill the DS::DigitPMT object. More details on the waveform analysis are provided in Waveform analysis.