diff --git a/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/DerivationFrameworkInDet/EGammaTracksThinning.h b/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/DerivationFrameworkInDet/EGammaTracksThinning.h
index 56f541c3cd2153ee84f12ab133db6df85c4a865d..3a82873bc0d56be0bcfc24b3df0d7c567e5a0046 100644
--- a/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/DerivationFrameworkInDet/EGammaTracksThinning.h
+++ b/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/DerivationFrameworkInDet/EGammaTracksThinning.h
@@ -45,11 +45,11 @@ namespace DerivationFramework {
     double m_minEtEg;
 
     std::set<int> findGoodTracks(const TrackCollection* trackCont,
-                              TLorentzVector candHepLorentz, 
+                                 const TLorentzVector& candHepLorentz, 
                               double maxDeltaR) const ;
     
 
-    StatusCode thinTracks( const TrackCollection * trackCont , std::set<int> goodTracks ) const ;
+    StatusCode thinTracks( const TrackCollection * trackCont , const std::set<int>& goodTracks ) const ;
         
   };  
 }
diff --git a/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/src/EGammaTracksThinning.cxx b/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/src/EGammaTracksThinning.cxx
index f99fa6529d885fe347119ee4c900e627e8690ef2..028d79d029a6f4bf3756ac763d2ee6ac907a5a0d 100644
--- a/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/src/EGammaTracksThinning.cxx
+++ b/PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet/src/EGammaTracksThinning.cxx
@@ -150,7 +150,7 @@ StatusCode DerivationFramework::EGammaTracksThinning::doThinning() const {
 // =======================================================
 
 std::set<int> DerivationFramework::EGammaTracksThinning::findGoodTracks(const TrackCollection* trackCont,
-                                                               TLorentzVector candHepLorentz, 
+                                                               const TLorentzVector& candHepLorentz, 
                                                                double maxDeltaR ) const 
 {
 
@@ -197,7 +197,7 @@ std::set<int> DerivationFramework::EGammaTracksThinning::findGoodTracks(const Tr
 // =======================================================
 
 StatusCode DerivationFramework::EGammaTracksThinning::thinTracks( const TrackCollection * trackCollection , 
-                                                            std::set<int> m_goodTrackIDs ) const
+                                                                  const std::set<int>& m_goodTrackIDs ) const
 {
   
   ATH_MSG_DEBUG( "==> thinTracks " << name() << "..." );