Light simulation issue 3: Sampling

[YifanC]

Currently in the light simulation, we first sample the signal typically with high frequency and digitize to the readout ticks in a later stage.
The digitization is done through linear interpolation of the two high frequency sampling point.
The following functions matter here: light_sim.calc_light_detector_response(), light_sim.sipm_response_model() and light_sim.digitize_signal(). Maybe I'm overlooking something really important. I don't see the benefit of simulating with dense samples and then interpolating from the neighbours to the digitization rate.

Assuming we are not losing much by simulating directly at the digitization rate, then we could probably reduce the internal memory usage. This could be helpful for increasing the number of segments to match for the light backtracking.

Would anyone convince me why we should sampling with high frequency first? @mjkramer @krwood @liviocali @AWh1t3 @russellphysics @marjoleinvannuland

[marjoleinvannuland]

(Disclaimer: I don't know any of this for sure.) Right now I think there is no benefit of simulating at a high rate and then downsampling. But if we only have the low frequency simulated, we cannot study what the effect would be of going to a faster readout system, and this is something that we might be interested in. I do not understand why we need the interpolation, but also I did not look into this carefully at all.

[YifanC]

Hi @marjoleinvannuland , you can simulate sampling of higher frequency by adjusting light_digit_sample_spacing