Import Geant4 11.3.1 source tree

examples/advanced/HGCal_testbeam/History

@@ -4,6 +4,9 @@ See `CONTRIBUTING.rst` for details of **required** info/format for each entry,
 which **must** added in reverse chronological order (newest at the top). It must **not**
 be used as a substitute for writing good git commit messages!
 
+## 2025-02-28 Soon Yung Jun (exhgcaltb-V11-02-00)
+- Restore the original beam energy after it is modified
+- Ensure non-negative beam energy
 
 ## 2023-11-15 I. Hrivnacova (exhgcaltb-V11-01-01)
 - Updated vis.mac:

examples/advanced/HGCal_testbeam/src/PrimaryGeneratorAction.cc

@@ -219,12 +219,19 @@ void PrimaryGeneratorAction::GeneratePrimaries(G4Event *anEvent) {
       break;
     }
     // Particle momentum
-    if (fMomentumGaussianSpread > 0) {
-      double energy = fParticleGun->GetParticleEnergy();
-      energy += G4RandGauss::shoot(0., fMomentumGaussianSpread) * energy;
+    const G4double meanEnergy = fParticleGun->GetParticleEnergy();
+    G4bool energySpread = (fMomentumGaussianSpread > 0);
+    if (energySpread) {
+      const G4double energy = std::max(0.,
+          (1. + G4RandGauss::shoot(0., fMomentumGaussianSpread)) * meanEnergy);
       fParticleGun->SetParticleEnergy(energy);
     }
     fParticleGun->GeneratePrimaryVertex(anEvent);
+
+    // Restore the original energy if it was modified
+    if (energySpread) {
+      fParticleGun->SetParticleEnergy(meanEnergy);
+    }
   }
 }
 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

examples/advanced/HGCal_testbeam/testbeam_electron.out

@@ -11,7 +11,7 @@ Environment variable "G4FORCE_RUN_MANAGER_TYPE" enabled with value == Serial. Fo
 
 
 **************************************************************
- Geant4 version Name: geant4-11-03-ref-00    (6-December-2024)
+ Geant4 version Name: geant4-11-03-patch-01    (21-March-2025)
                        Copyright : Geant4 Collaboration
                       References : NIM A 506 (2003), 250-303
                                  : IEEE-TNS 53 (2006), 270-278