fix

[u/mrichter/AliRoot.git] / ZDC / AliZDCv3.cxx

diff --git a/ZDC/AliZDCv3.cxx b/ZDC/AliZDCv3.cxx
index 534da4cc8f50e33b45289a356b614c27a04ed8c9..ae43b808d2c933d05de40ca132985803a1060eeb 100644 (file)
--- a/ZDC/AliZDCv3.cxx
+++ b/ZDC/AliZDCv3.cxx
@@ -2466,14 +2466,19 @@ void AliZDCv3::StepManager()
     // Ch. debug
     //printf("\t *** det %d vol %d xdet(%f, %f)\n",vol[0], vol[1], xdet[0], xdet[1]);
     
+    
   // Store impact point and kinetic energy of the ENTERING particle
     
       if(gMC->IsTrackEntering()){
         //Particle energy
         gMC->TrackMomentum(p[0],p[1],p[2],p[3]);
         hits[3] = p[3];
-        // Impact point on ZDC  
-        hits[4] = xdet[0];
+        // Impact point on ZDC
+       // X takes into account the LHC x-axis sign
+       // which is opposite to positive x on detcetor front face
+       // for side A detectors (ZNA and ZPA)  
+        if(vol[0]==4 || vol[0]==5) hits[4] = -xdet[0];
+       else hits[4] = xdet[0];
         hits[5] = xdet[1];
        hits[6] = 0;
         hits[7] = 0;