The x position 0 <-> time bin 0 - x increases TOWARDS interaction point (M.Ivanov)

[u/mrichter/AliRoot.git] / TRD / AliTRDclusterizer.cxx

diff --git a/TRD/AliTRDclusterizer.cxx b/TRD/AliTRDclusterizer.cxx
index 16aea8a5b4b2c3a32e8cd7aed909e173f6e6489f..f078f779488ee302ffa0e5cc3febb6156055dde6 100644 (file)
--- a/TRD/AliTRDclusterizer.cxx
+++ b/TRD/AliTRDclusterizer.cxx
@@ -304,18 +304,22 @@ AliTRDcluster* AliTRDclusterizer::AddCluster(Double_t *pos, Int_t timebin, Int_t
 }
 
 //_____________________________________________________________________________
-Double_t AliTRDclusterizer::CalcXposFromTimebin(Float_t timebin, Float_t vdrift)
+Double_t AliTRDclusterizer::CalcXposFromTimebin(Float_t timebin, Int_t idet, Int_t col, Int_t row)
 {
   //
   // Calculates the local x position in the detector from the timebin, depends on the drift velocity
-  // The timebin has to be t0 corrected already
+  // and t0
   //
   
   AliTRDcalibDB* calibration = AliTRDcalibDB::Instance();
   if (!calibration)
     return -1;
-    
-  Int_t totalTimebins = calibration->GetNumberOfTimeBins();
+
+  Float_t vdrift = calibration->GetVdrift(idet, col, row);  
+  Float_t t0 = calibration->GetT0(idet, col, row);
   Float_t samplingFrequency = calibration->GetSamplingFrequency();
-  return (totalTimebins - timebin) / samplingFrequency * vdrift;
+
+  timebin -= t0;
+
+  return timebin / samplingFrequency * vdrift;
 }