If 1 is set, detection area was extended with muon-range dynamically event by event.
By default, 1 for NuMu and NuTau, 0 for NuE.
This parameter should be same for all simulation set and it’s obvious from generation script, then it is removed.
If you need to use the value in your script use:
CAUTION:This is total number of events per file, with neutrino and anti-neutrino.
When you weight with “per particle type” (e.g. atmospheric neutrino flux), the required number of event per file should be “per particle type” (it is known as famous factor 2 for atmospheric neutrino weight).
If you use OneWeightPerType parameter instead of OneWeight, you don’t need to compensate the factor.
Injected one NuTau and regeneration process occurred, arrived N nus : NInIceNus = N
Injected 100 NuTau and only one NuTau is selected to process NuGen, and regeneration process increased the child neutrinos N : NInIceNus = 100 + N -1 (-1 for removing double counting of selected neutrino)
Interaction info at detection volume (final interaction)¶
Bjorken’s X parameter for final interaction. See InteractionBase::SetSecondaryLepton() for how it is used.
(used to calculate outgoing angle between InIce neutrino and a secondary track)
Renamed from TotalInteractionProbabilityWeight.
This is the total weight to compensate all weighted simulation in NuGen EXCEPT FOR TypeWeight.
See InteractionInfo::GetTotalWeight() for details.
If you use only one dataset or datasets with same energy range and zenith range or datasets which does not have any overwrap in energy range and zenith range, you may use pre-stored OneWeight to get event weight.
The perfered way to weight neutrino-generator samples can be performed is with simweights.
However, the insturcitons below can be used as well.
how to weight with atmospheric neutrino flux using OneWeight¶
prepare atmospheric flux. Use NewNuFlux module or neutrinoflux module.
For how to use neutrinoflux, see Chad’s note.
Both flux modules returns values with a unit of [\(GeV^{-1} sr^{-1} cm^{-2} sec^{-1}\)].
Note that atmospheric neutrino flux is given PER TYPE. Since we generate both Nu and NuBar, we have to compensate number of generated events with the production-ratio of each primary type. With a default setting, we generate Nu:NuBar = 1:1 so that the type_weight is always 0.5.
how to weight with \(E^{-2}\) flux using OneWeight¶
The “norm” is one of the physics parameters to fit in most cases. N represents number of total neutrinos plus anti-neutrinos.
The equation above has been used long time, however, if we want to change production ratio of Nu and NuBar, this formula is not applicable any more. Use OneWeightPerType.
However, since we (historically) use “sum of Nu and NuBar” (norm_for_nu + norm_for_nubar) for estimation of astrophysical flux, we have to double the “norm_per_type” to get same value as old definition. Because the “norm_per_type” is a fit parameter, we need to multiply a compensation factor 0.5 to double the “norm_per_type”
then norm_for_all will be a factor two larger than norm_per_type.
Instead of using oneweight / type_weight, you may use OneWeightPerType, because
oneweightpertype=oneweight/type_weight
The following figure shows comparison of three NuGen outputs. Blue and Cyan is generated with NuMu:NuMuBar = 1:1. Blue uses OneWeight for weighting. Cyan uses OneWeightPerType instead but missing factor 0.5 on numerator of weight. Green is generated with NuMu:NuMuBar=1.2 , using OneWeightPerType for weight and multiplied factor 0.5 to numerator.
This parameter gives the ratio of the given particle type.
For standard production, we generate Nu:NuBar 1:1 so that the parameter is always 0.5.
To keep consistency of the definition of OneWeight, the TypeWeight parameter is not included in TotalWeight and OneWeight.
On the other hand, OneWeightPerType parameter contains the factor of TypeWeight.
This will be negligible for energy less than EeV. For such high E neutrino, the interaction vertex should concentrate on the beginning of the detection volume, while we uniformly distribute the vertex point within the detection volume. This parameter compensate the effect.
