Add features for Gadolinium neutron capture

[nickwp]

This pull request includes:

• Option to set Gd doping and concentration in mac file (default is for undoped water if these lines are missing, unless Gd is added manually in detector setup code in which case default concentration is 0.1%), set using lines like:

/WCSim/DopedWater false
/WCSim/DopingConcentration 0.1

• Option to save neutron capture truth information (capture position, time, nucleus, and resulting gamma directions and energies) as well as neutron tracks to output file:

/WCSim/SaveCapture true

• Additional neutron capture model code added for alternative GLG4Sim and ANNRI models
• Option to choose neutron capture model in jobOptions.mac file, can be "Default" (whatever the current physics list defaults to), "HP", "Rad", "GLG4Sim" or "ANNRI". E.g.:

/WCSim/physics/nCapture HP

[cvilelahep]

Hi @nickwp,

This all looks good to me.

I just have one question: you copied over the ANNRI Gd capture model -- does this mean this model is public? If we add it to the WCSim code it will become available to the world, since WCSim is open source. If this is a problem we can find a way around it, such as hosting the ANNRI code in a private repository under the NuPRISM organization, for example.

Cheers,
Cris

[nickwp]

Hi Cris,

Yes, sorry, I think this code should not be public. I had actually not realised that the nuPRISM WCSim was public, but in any case it doesn't matter since my own fork is also public, and the commit is already there.

I will have to rebase my branch, remove the commits, and force the push to my github fork, to make sure it is removed entirely rather than still available in the history. I'm not sure how this will affect this pull request, but if needed I'll close this and create a new one.

For now I think it's best to just leave out the ANNRI code, if we need to add it in future we can use your solution with a private repository.

Thanks,
Nick

[nickwp]

Hi Cris,

I've performed the rebase and all seems fine with the ANNRI code removed.
I've kept a separate branch locally with the code, which can be put in a private repo if we want to use that model.

Thanks,
Nick