Problem 2594 - Neutrino-nucleus interactions not activated for tau neutrinos
Summary: Neutrino-nucleus interactions not activated for tau neutrinos
Status: ASSIGNED
Alias: None
Product: Geant4
Classification: Unclassified
Component: physics_lists (show other problems)
Version: 11.2
Hardware: All All
: P4 normal
Assignee: Vladimir.Ivantchenko
URL:
Depends on:
Blocks:
 
Reported: 2024-02-13 17:01 CET by Simon
Modified: 2024-02-14 11:39 CET (History)
1 user (show)

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Description Simon 2024-02-13 17:01:21 CET
In `G4NeutrinoPhysics`, the tau neutrinos do not seem to have any neutrino-nucleus interactions. This is not an issue for muon and electron neutrinos. This is likely caused by a mistake here: https://github.com/Geant4/geant4/blob/master/source/physics_lists/constructors/gamma_lepto_nuclear/src/G4NeutrinoPhysics.cc#L241-L243, which is 
```
  for (G4int i=4; i<=5; ++i) {
    p[i]->GetProcessManager()->AddDiscreteProcess(theNuMuNucleusProcess);
  }
```
Here, `theNuMuNucleusProcess` is added to the tau neutrinos, when `theNuTauNucleusProcess` should be added. This is easily resolved by changing the code to

```
  for (G4int i=4; i<=5; ++i) {
    p[i]->GetProcessManager()->AddDiscreteProcess(theNuTauNucleusProcess);
  }
```
Comment 1 Simon 2024-02-14 11:39:58 CET
Hello,
I tried implementing the change I wrote about in my last comment and recompiled Geant4 but the problem seems to persist. Looking at the source code of https://github.com/Geant4/geant4/blob/master/source/processes/hadronic/cross_sections/src/G4TauNeutrinoNucleusTotXsc.cc, there seem to be several references to the muon neutrino instead of the tau neutrino. Is this intentional or are those also bugs? Do you have any suggestions or workarounds to make tau neutrino-nucleus interactions work in Geant4?