+//______________________________________________________________________________
+Bool_t AliESDZDC::GetZNCentroidInPbPb(Float_t beamEne, Double_t centrZNC[2], Double_t centrZNA[2])
+{
+ // Provide coordinates of centroid over ZN (side C) front face
+ if(beamEne==0){
+ printf(" ZDC centroid in PbPb can't be calculated with E_beam = 0 !!!\n");
+ for(Int_t jj=0; jj<2; jj++) fZNCCentrCoord[jj] = 999.;
+ return kFALSE;
+ }
+
+ const Float_t x[4] = {-1.75, 1.75, -1.75, 1.75};
+ const Float_t y[4] = {-1.75, -1.75, 1.75, 1.75};
+ const Float_t alpha=0.395;
+ Float_t numXZNC=0., numYZNC=0., denZNC=0., cZNC, wZNC;
+ Float_t numXZNA=0., numYZNA=0., denZNA=0., cZNA, wZNA;
+ //
+ for(Int_t i=0; i<4; i++){
+ if(fZN1TowerEnergy[i+1]>0.) {
+ wZNC = TMath::Power(fZN1TowerEnergy[i+1], alpha);
+ numXZNC += x[i]*wZNC;
+ numYZNC += y[i]*wZNC;
+ denZNC += wZNC;
+ }
+ if(fZN2TowerEnergy[i+1]>0.) {
+ wZNA = TMath::Power(fZN1TowerEnergy[i+1], alpha);
+ numXZNA += x[i]*wZNA;
+ numYZNA += y[i]*wZNA;
+ denZNA += wZNA;
+ }
+ }
+ //
+ if(denZNC!=0){
+ Float_t nSpecnC = fZDCN1Energy/beamEne;
+ cZNC = 1.89358-0.71262/(nSpecnC+0.71789);
+ fZNCCentrCoord[0] = cZNC*numXZNC/denZNC;
+ fZNCCentrCoord[1] = cZNC*numYZNC/denZNC;
+ }
+ else{
+ fZNCCentrCoord[0] = fZNCCentrCoord[1] = 999.;
+ }
+ if(denZNA!=0){
+ Float_t nSpecnA = fZDCN1Energy/beamEne;
+ cZNA = 1.89358-0.71262/(nSpecnA+0.71789);
+ fZNCCentrCoord[0] = cZNA*numXZNA/denZNA;
+ fZNCCentrCoord[1] = cZNA*numYZNA/denZNA;
+ }
+ else{
+ fZNACentrCoord[0] = fZNACentrCoord[1] = 999.;
+ }
+ //
+ for(Int_t il=0; il<2; il++){
+ centrZNC[il] = fZNCCentrCoord[il];
+ centrZNA[il] = fZNACentrCoord[il];
+ }
+
+ return kTRUE;
+}