// This is the Bethe-Bloch function normalised to 1 at the minimum
//
Double_t bg2=bg*bg;
- Double_t bethe=(1.+ bg2)/bg2*(log(5940*bg2) - bg2/(1.+ bg2));
+ Double_t bethe;
+ if (bg<3.5e1)
+ bethe=(1.+ bg2)/bg2*(log(5940*bg2) - bg2/(1.+ bg2));
+ else // Density effect ( approximately :)
+ bethe=1.15*(1.+ bg2)/bg2*(log(3.5*5940*bg) - bg2/(1.+ bg2));
return bethe/11.091;
}