Improved Bethe-Bloch formula (Yuri)
authorhristov <hristov@f7af4fe6-9843-0410-8265-dc069ae4e863>
Wed, 29 Oct 2008 20:42:46 +0000 (20:42 +0000)
committerhristov <hristov@f7af4fe6-9843-0410-8265-dc069ae4e863>
Wed, 29 Oct 2008 20:42:46 +0000 (20:42 +0000)
TPC/AliTPCpidESD.cxx

index 58f6638..cc64763 100644 (file)
@@ -44,12 +44,9 @@ Double_t AliTPCpidESD::Bethe(Double_t bg) {
   // This is the Bethe-Bloch function normalised to 1 at the minimum
   //
   Double_t bg2=bg*bg;
-  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;
+  Double_t beta2 = bg2/(1.+ bg2);
+
+  return 8.62702e-2*(9.14550 - beta2 - TMath::Log(3.51000e-5 + 1./bg2))/beta2;
 }
 
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