diff --git a/NPLib/Physics/NPReaction.cxx b/NPLib/Physics/NPReaction.cxx
index ecf1c4d353c7c7889ac52cb1d4758d235f6356ce..6f890404c9fc15904a6392a296bfb55d3b1d29b6 100644
--- a/NPLib/Physics/NPReaction.cxx
+++ b/NPLib/Physics/NPReaction.cxx
@@ -301,7 +301,7 @@ double Reaction::ReconstructRelativistic(double EnergyLab, double ThetaLab, doub
   double E3 = m3 + EnergyLab;
   double p_Lab_3 = sqrt(E3 * E3 - m3 * m3);
   fEnergyImpulsionLab_3 =
-      TLorentzVector(p_Lab_3 * sin(ThetaLab) * cos(PhiLab), p_Lab_3 * sin(PhiLab), p_Lab_3 * cos(ThetaLab), E3);
+      TLorentzVector(p_Lab_3 * sin(ThetaLab) * cos(PhiLab), p_Lab_3 * sin(ThetaLab) * sin(PhiLab), p_Lab_3 * cos(ThetaLab), E3);
   fEnergyImpulsionLab_4 = fTotalEnergyImpulsionLab - fEnergyImpulsionLab_3;
 
   double Eex = fEnergyImpulsionLab_4.Mag() - fParticle4.Mass();
@@ -313,7 +313,7 @@ TLorentzVector Reaction::LorentzAfterReaction(double EnergyLab, double ThetaLab,
   double E3 = m3 + EnergyLab;
   double p_Lab_3 = sqrt(E3 * E3 - m3 * m3);
   fEnergyImpulsionLab_3 =
-      TLorentzVector(p_Lab_3 * sin(ThetaLab) * cos(PhiLab), p_Lab_3 * sin(PhiLab), p_Lab_3 * cos(ThetaLab), E3);
+      TLorentzVector(p_Lab_3 * sin(ThetaLab) * cos(PhiLab), p_Lab_3 * sin(ThetaLab) * sin(PhiLab), p_Lab_3 * cos(ThetaLab), E3);
   fEnergyImpulsionLab_4 = fTotalEnergyImpulsionLab - fEnergyImpulsionLab_3;
   return fEnergyImpulsionLab_4;
 }