Neutrino momentum truncated to 50GeV in 2018 pre-production

[anupama-reghunath]

Attached are the two plots from the neutrino preproduction sample (/eos/experiment/ship/data/Mbias/background-prod-2018/pythia8_Geant4_1.0_withCharm_nu.root).

Does anyone know why we force the P_total < 50GeV in logP vs logPt (right plot) ?

Relevant code here, but no supporting comments unfortunately.
https://github.com/ShipSoft/FairShip/blob/5364119cdf3cf33c77d1ea46e091fe4fde972e6d/macro/makeDecay.py#L142C1-L143C75

[antonioiuliano2]

Hello Anupama,
The 2D spectrum is used here:

FairShip/shipgen/GenieGenerator.cxx

Line 486 in 5364119

Double_t ptlog10=pyslice[idhnu][nbx]->GetRandom();

It is used to generate the transverse component of the neutrino momenta, since GENIE gevgen will always generate them along z.
It does not impede to simulate neutrinos over 50 GeV (we simulated them so far), but it will consider it as a 50 GeV one to randomly generate the PT according to the last slice of the 2D plot

Unfortunately, I do not know why the momentum is truncated in makeDecay. I would assume due to low statistics at high momentum, but we should write to Thomas to be sure.

[eduard322]

To be honest, it would be better to get the new P-Pt distribution without 50 GeV limit (I had a problem with that when I wanted to make neutrino signal in SND generate more efficiently by setting a cut on Pt corresponding to the acceptance of SND), but I guess it's a task for the upcoming production

[olantwin]

@eduard322 @antonioiuliano2 What concretely should be changed for the new production to address this?

CC @THanae

[eduard322]

@eduard322 @antonioiuliano2 What concretely should be changed for the new production to address this?

CC @THanae

I guess these lines are redundant (please, confirm @antonioiuliano2 ):

FairShip/macro/makeDecay.py

Lines 145 to 146 in 79e9817

	l10ptot=min(max(ROOT.TMath.Log10(ptot),-0.3),1.69999)
	l10pt=min(max(ROOT.TMath.Log10(ROOT.TMath.Sqrt(pt2)),-2.),0.4999)

But I would ask you to make a straightforward link between the neutrino ntuples and the final 1d and 2d histograms, because right now it is not clear at all how to produce the simular results in case of using ntuples and in case of using the histograms made from these ntuples :/

[olantwin]

Can you make a small PR please?
We'll try to document things as thoroughly as possible this time around.

[eduard322]

#958