+Double_t AliFastGlauber::MeanOverlap(Double_t b1, Double_t b2)
+{
+//
+// Calculate the mean overlap for impact parameter range b1 .. b2
+//
+ Double_t sum = 0.;
+ Double_t sumc = 0.;
+ Double_t b = b1;
+
+ while (b < b2-0.005) {
+ Double_t nc = GetNumberOfCollisions(b);
+ sum += 10. * fgWStaa->Eval(b) * fgWSgeo->Eval(b) * 0.01 / (1. - TMath::Exp(-nc));
+ sumc += 10. * fgWSgeo->Eval(b) * 0.01;
+ b += 0.01;
+ }
+ return (sum / CrossSection(b1, b2));
+}
+
+
+Double_t AliFastGlauber::MeanNumberOfCollisionsPerEvent(Double_t b1, Double_t b2)
+{
+//
+// Calculate the mean number of collisions per event for impact parameter range b1 .. b2
+//
+ Double_t sum = 0.;
+ Double_t sumc = 0.;
+ Double_t b = b1;
+
+ while (b < b2-0.005) {
+ Double_t nc = GetNumberOfCollisions(b);
+ sum += nc / (1. - TMath::Exp(-nc)) * 10. * fgWSgeo->Eval(b) * 0.01;
+ sumc += 10. * fgWSgeo->Eval(b) * 0.01;
+ b += 0.01;
+ }
+ return (sum / CrossSection(b1, b2));
+}
+
+