Add DefineVariables to put beta and betachi2 into tree

src/THcHallCSpectrometer.cxx

@@ -111,6 +111,25 @@ THcHallCSpectrometer::~THcHallCSpectrometer()
   delete [] f2XHits;              f2XHits = NULL;            // Ahmed  
   delete [] f2YHits;              f2YHits = NULL;            // Ahmed  
 
+  DefineVariables( kDelete );
+}
+
+//_____________________________________________________________________________
+Int_t THaSpectrometer::DefineVariables( EMode mode )
+{
+  // Define/delete standard variables for a spectrometer (tracks etc.)
+  // Can be overridden or extended by derived (actual) apparatuses
+
+  if( mode == kDefine && fIsSetup ) return kOK;
+  THaSpectrometer::DefineVariables( mode );
+
+  RVarDef vars[] = {
+    { "tr.beta", "Beta", "fTracks,THaTrack.GetBeta()"},
+    { "tr.betachisq", "Chi2 of beta", "fTracks,THaTrack.GetBetaChi2()"},
+    { 0 }
+  };
+  
+  return DefineVarsFromList( vars, mode );
 }
 
 //_____________________________________________________________________________