SPE spec bug fix, adding trigger truth

[zhut19]

What is the problem / what does the code in this PR do

• Fixing a bug in the SPE spectrum, we were only using channel 0 for nT.
• Also adding trigger truth to the truth values, including
  • n_photon_trigger: number of photons that should pass the ADC trigger assuming no noise fluctuation; this also considers the possibility of one photon generating 2 PE and thus having a higher chance of passing ADC threshold.
  • n_pe_trigger: number of photons + dpe that should pass the ADC trigger assuming no noise fluctuation
• Adding a new field raw_area: Sum of the gain per PE triggered
• Those three fields has a copy of bottom only values

[zhut19]

Hi @JoranAngevaare, I am adding the required fields including n_photon_trigger to the truth output. But also realized there's a pretty obvious bug that for nT, we were using only the channel[0] single photon electron spectrum for all channels.

[FaroutYLq]

Thanks a lot for this PR! This is really helpful.

[JoranAngevaare]

Thanks Tianyu for this PR! Much appreciated. One piece of the code I don't fully follow, can you help me a bit?

[JoranAngevaare]

I tested it and it really works great, thanks again Tianyu!