Compute particle energy is negative value passed to AddTrack (#3711)

preghenella · web-flow · commit 35f426524069 · 2020-06-04T16:45:37.000+02:00
* Compute particle energy is negative value passed to AddTrack
diff --git a/Generators/src/PrimaryGenerator.cxx b/Generators/src/PrimaryGenerator.cxx
@@ -128,7 +128,8 @@ void PrimaryGenerator::AddTrack(Int_t pdgid, Double_t px, Double_t py, Double_t
   vz += fVertex.Z();
 
   /** check if particle to be tracked exists in PDG database **/
-  if (wanttracking && !TDatabasePDG::Instance()->GetParticle(pdgid)) {
+  auto particlePDG = TDatabasePDG::Instance()->GetParticle(pdgid);
+  if (wanttracking && !particlePDG) {
     LOG(WARN) << "Particle to be tracked is not defined in PDG: pdg = " << pdgid;
     wanttracking = false;
   }
@@ -162,6 +163,12 @@ void PrimaryGenerator::AddTrack(Int_t pdgid, Double_t px, Double_t py, Double_t
     pdgid = gRandom->Uniform() < 0.5 ? 310 : 130;
   }
 
+  /** compute particle energy if negative **/
+  if (e < 0) {
+    double mass = particlePDG ? particlePDG->Mass() : 0.;
+    e = std::sqrt(mass * mass + px * px + py * py + pz * pz);
+  }
+
   /** add track to stack **/
   fStack->PushTrack(doTracking, parent, pdgid, px, py, pz,
                     e, vx, vy, vz, tof, polx, poly, polz, proc, ntr,
