Adding a score for the particles killed by the cutoff

[cfichtlscherer]

At the moment, it is not possible to find out what fraction of the particles was killed by the cutoffs (e.g. energy).
I would suggest we add a score for this.

https://openmc.slack.com/archives/C9E8ULKC3/p1684762557424209

[shimwell]

Interesting idea thanks for bringing this up on slack and here.

Wondering if we do have a tally for this then perhaps it could be added to the global tallies like leakage is. Then each simulation could report on leakage and low energy cut of losses.

Might help the user know if particles lost in this way are excessive for their particular model.

[cfichtlscherer]

Hey, I'd like to turn to this next. If you have time, that has no hurry I would be happy about a short assessment. @shimwell @gridley @paulromano 😃

• should we add it at all?
• should we add it as a global tally?

I would like to have an exact breakdown, X photons were killed by the energy cutoff and Y neutrons by the time cutoff.

On the other hand, I don't know how helpful it is when a particle has a lot of children, what do I do with the information that some of those children were killed, you actually have to put that into a relation to the number of all children. Do we then also want to insert a counter for this?

Please don't feel rushed or stressed, there is no rush to do this, but I welcome your ideas. Thanks a lot already 😃

[shimwell]

It would give a better insight into the simulation if these factions were reported. I currently don't know what fraction of particles get cut out by energy cut-offs.

I think the current leakage tally groups both photons and neutrons, so for a coupled np simulation I would find the splitting of neutrons and photons in the leakage tally useful. Then I would know how many neutrons from the neutron source escaped, which I currently don't know from the leakage tally as it includes both particles.

A similar splitting for neutrons and photons on the time cuts would also be handy for people doing time of flight detector simulations. Which we do in ICF fusion a fair amount. I guess this could save computing time.

I would be keen to see all added as global tallies but perhaps one at a time. I have no idea how this might impact the overall performance. I would make use of the feature if added.