diff --git a/bind/example.py b/bind/example.py
new file mode 100644
index 0000000..2865bed
--- /dev/null
+++ b/bind/example.py
@@ -0,0 +1,11 @@
+
+from bindings import ConstructionWrapper, SystemBuilder
+
+cw = ConstructionWrapper()
+cw.addLayer(10,"G4_Si",True)
+cw.addLayer(1,"G4_Pb",False)
+cw.addLayer(10,"G4_Si",False)
+
+sb = SystemBuilder()
+sb.init(cw)
+sb.run_batch(100, "e-", 1000, 5000)
\ No newline at end of file
diff --git a/src/PrimaryGeneratorAction.cc b/src/PrimaryGeneratorAction.cc
index 88b0477..a053701 100644
--- a/src/PrimaryGeneratorAction.cc
+++ b/src/PrimaryGeneratorAction.cc
@@ -83,6 +83,11 @@ void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
 
   auto particleDefinition
     = G4ParticleTable::GetParticleTable()->FindParticle(partSpecies);
+  if(particleDefinition == nullptr){
+    G4cout << "Particle " << partSpecies << " not found" << G4endl;
+    throw std::runtime_error("Particle not found");
+    return;
+  }
   fParticleGun->SetParticleDefinition(particleDefinition);
   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0.,0.,1.));
   fParticleGun->SetParticleEnergy(partEnergy*MeV);
diff --git a/src/SystemBuilder.cc b/src/SystemBuilder.cc
index 6e8cf91..4814791 100644
--- a/src/SystemBuilder.cc
+++ b/src/SystemBuilder.cc
@@ -60,7 +60,7 @@ void SystemBuilder::run_gui(){
 }
 
 void SystemBuilder::run_batch(int nEvents, std::string partSpecies, double minEnergy, double maxEnergy){
-    actionInitialization->setGeneratorProperties(minEnergy, maxEnergy, partSpecies);
+    actionInitialization->setGeneratorProperties(minEnergy, maxEnergy, (G4String)partSpecies);
     UImanager->ApplyCommand("/run/initialize");
     runManager->BeamOn(nEvents);
 }
\ No newline at end of file