Nuhist cut

[eduard322]

Fixed the 50 GeV cut for the production of P-Pt histograms of neutrino. I would investigate more what exactly this script does and what was the reason for that before using it. I don't think this is an urgent thing: it does not affect the production at all.

[olantwin]

If this doesn't affect the production, can we run it over the files of the old production and generate the uncut histograms?

[antonioiuliano2]

Yes, I agree with Oliver.

I would check it, because I am worried about how the high momentum bins with low statistics would be treated by GenieGenerator during the simulation.

[olantwin]

How do we move forward on this?

[eduard322]

Actually I have some questions:

1. Why do we simulate decays using pythia if we have EvtGen now?
2. I still see many limitations because of the way we generate neutrino signal/bkg:
   a. The GENIE dataset that is used in all the bkg studies is simulated for nu-Fe56 interaction, which is not correct (though give us an undefined confidence that we are safe)
   b. The subsequent number of interactions using the fixed cross-section for DIS is also incorrect: for our energies ~half of the interactions will be resonance scattering of neutrinos that have a different cross-section function. And you are not able to use the basic formula for that as well: the spectrum of interacted neutrinos differ from the initial neutrino spectrum, making the whole pipeline of the neutrino studies intransparent.
   gevgen_fnal would be the best solution for that...

[olantwin]

Actually I have some questions:

1. Why do we simulate decays using pythia if we have EvtGen now?

Right now it's pretty ad hoc what is done with Pythia and what with EvtGen. This is a physics question, which should be studied and discussed at a physics meeting.

2. I still see many limitations because of the way we generate neutrino signal/bkg:
   a. The GENIE dataset that is used in all the bkg studies is simulated for nu-Fe56 interaction, which is not correct (though give us an undefined confidence that we are safe)
   b. The subsequent number of interactions using the fixed cross-section for DIS is also incorrect: for our energies ~half of the interactions will be resonance scattering of neutrinos that have a different cross-section function. And you are not able to use the basic formula for that as well: the spectrum of interacted neutrinos differ from the initial neutrino spectrum, making the whole pipeline of the neutrino studies intransparent.
   gevgen_fnal would be the best solution for that...

Then let's try to do this properly. Again, probably something we should probably discuss at a physics meeting, but here it's much clearer that we need to change what we do.

[anupama-reghunath]

Are we sure this is the step(or the only step) for the production of these histograms? I also see the same weird cut-off in extractNeutrinosAndUpdateWeight.py.

[antonioiuliano2]

Are we sure this is the step(or the only step) for the production of these histograms? I also see the same weird cut-off in extractNeutrinosAndUpdateWeight.py.

You are right, thank you! The extractNeutrinos fills only the histograms, while the MakeDecay does all the processing chain. So the first script is the one we should use to test the effect of the cut on the already existing past simulation files.

For all the other comments, I agree on using gevgen_fnal. Ideally, we would want to use the same procedure adopted in SND@LHC, where GENIE takes care of the whole pipeline at once, from the incoming neutrino flux produced in the main target to the interacting neutrino spectra in the target geometry.

However when I tried it a few years ago I could not load the geometry, due to all SHiP volumes....

[olantwin]

However when I tried it a few years ago I could not load the geometry, due to all SHiP volumes....

Did you make note of what exactly the issues are? The geometry is in our control, if the way we describe it causes problems, we can fix that.

Please check with @eduard322 , he presented this and other issues today: https://indico.cern.ch/event/1594362/#2-neutrino-simulation-and-part