Possibility to calculate the DCA between two ESD track. The V0 and cascade vertexes...

[u/mrichter/AliRoot.git] / ITS / AliITStrackV2.cxx

diff --git a/ITS/AliITStrackV2.cxx b/ITS/AliITStrackV2.cxx
index ae042babdd838b3ab2e4c087b1ab0415b047942f..36d4e7c9af792e9856d90f73fb7d799b44f7473d 100644 (file)
--- a/ITS/AliITStrackV2.cxx
+++ b/ITS/AliITStrackV2.cxx
@@ -734,3 +734,30 @@ void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
 
   SetdEdx(dedx);
 }
+
+Double_t AliITStrackV2::
+PropagateToDCA(AliKalmanTrack *p, Double_t d, Double_t x0) {
+  //--------------------------------------------------------------
+  // Propagates this track and the argument track to the position of the
+  // distance of closest approach. 
+  // Returns the (weighed !) distance of closest approach.
+  //--------------------------------------------------------------
+  Double_t xthis, xp, dca;
+  {
+  //Temporary solution
+  Double_t b=1./GetLocalConvConst()/kB2C;
+  AliExternalTrackParam dummy1(*this), dummy2(*p); 
+  dca=dummy1.GetDCA(&dummy2,b,xthis,xp);
+  }
+  if (!PropagateTo(xthis,d,x0)) {
+    //AliWarning(" propagation failed !");
+    return 1e+33;
+  }  
+
+  if (!p->PropagateTo(xp,d,x0)) {
+    //AliWarning(" propagation failed !";
+    return 1e+33;
+  }  
+
+  return dca;
+}