Added SimDRCalorimeterHit for dual-readout

[wonyongc]

BEGINRELEASENOTES

• Added SimDRCalorimeterHit for optical photon dual-readout. Records number of scintillation/Cerenkov photons per hit as well as the wavelength/timing bins.

ENDRELEASENOTES

[wonyongc]

Hi,
I have been developing a full simulation for a segmented crystal ECAL (CalVision/MAXICC collaborations) and am now submitting PRs to get the simulation into key4hep.
I needed to make a new datatype to store the scintllation/cerenkov hit information. So far I have simply extended the edm4hep schema with a custom 'edm4dr' schema in the simulation repo, but to merge into k4geo, it seems like it would be a better option (or the only one) to have this new schema merged into the main edm4hep.
Please let me know if I should take a different approach.
Thanks,
Wonyong

[andresailer]

Why do you need these when there is already cellID?

[andresailer]

What is stored in these arrays? What is the index? Why 6000?
This feels awfully inefficient.

[BrieucF]

Hi Wonyong, thanks.

Do I understand correctly that, for DRCrystals, SimCalorimeter hits are not an option? Is it because, unlike for DRFibers (see key4hep/k4geo#411), both C and S photons are produced by the same sensitive volume?

Is the need for storing wavelength coming from the fact that you need it for wavelength dependent effects in the digitization?

[wonyongc]

Hi Brieuc,
Yes and yes. However, after discussing with Marco Lucchini we decided to keep this simpler for now and only include the counts and not the actual bins, which should also address Andre's comments. I will update this.

[wonyongc]

Hi, I've updated the class wrt the comments above. Please take a look.

[SanghyunKo]

I was wondering whether we could just use two collections (one for the scintillation, one for the cherenkov channel) instead of implementing the dedicated data format (though I also opt to include the time information to the SimCalorimeterHit on par with the RawCalorimeterHit)

[tmadlener]

I was wondering whether we could just use two collections (one for the scintillation, one for the cherenkov channel)

If that would be possible then I think that would be the easiest solution. Do you already have some digitization code, where it could be exercises how workable that solution actually is there?

(though I also opt to include the time information to the SimCalorimeterHit

We already discussed adding a time field to the SimCalorimeterHit in #147 without coming to a real conclusion in the end.

The main open question at that point was, what should be stored in the time field for the SimCalorimeterHit? Since there are probably several contributions to one hit, it's not entirely obvious which one of those it should be. If there is a choice that works for the majority of cases then we could maybe add that and clearly document which time should be stored there. However, that will also mean that the sensitive action (or the EDM4hep output?) would be responsible for filling that information appropriately.

[andresailer]

Why produced photons? Why not recorded photons? Similar to having the avg arrival time of photons recorded in the time fields?

[BrieucF]

This is a SIM level object, I guess we should leave the possibility to treat effects such as efficiency in a subsequent digitizer (though it is indeed sometimes interesting to leak part of the digitization in the SDAction)

[andresailer]

But then the tAvg should also come from the digitiser and not be calculated here already?