Use for PID in ITS the Bethe Bloch from AliExternalTrackParam

diff --git a/ITS/AliITSdEdxAnalyzer.cxx b/ITS/AliITSdEdxAnalyzer.cxx
index 3d61c24a04b5d3784c35125ca3559b4880ed4f92..fe9b9d19cbb2b36af67283eb6079e09b49055f57 100644 (file)
--- a/ITS/AliITSdEdxAnalyzer.cxx
+++ b/ITS/AliITSdEdxAnalyzer.cxx
@@ -224,7 +224,7 @@ Double_t AliITSdEdxAnalyzer::BetheBloch(const Float_t p, const Float_t m) const
   Double_t dedxbb=0.;
   if(fBBmodel==0){
     Double_t betagamma=p/m;
-    Double_t conv=fDensity*1E6*fThickness/116.31*fMIP;
+    Double_t conv=fDensity*1E6*fThickness/116.24*fMIP;
     dedxbb=conv*AliExternalTrackParam::BetheBlochSolid(betagamma);
   }else if(fBBmodel==1){
     dedxbb=fMIP*AliITSpidESD::Bethe(p,m);

diff --git a/ITS/AliITSpidESD.cxx b/ITS/AliITSpidESD.cxx
index 2d464c08aa9b8de332a4ac084c0516e869e92e06..4c6c0572e34de4d8d1638f63c62b09f6c5f78030 100644 (file)
--- a/ITS/AliITSpidESD.cxx
+++ b/ITS/AliITSpidESD.cxx
@@ -25,6 +25,7 @@
 
 #include "AliITSpidESD.h"
 #include "AliESDtrack.h"
+#include "AliExternalTrackParam.h"
 
 ClassImp(AliITSpidESD)
 
@@ -36,22 +37,12 @@ AliITSpidESD::AliITSpidESD():TObject(){
 }
 
 Double_t AliITSpidESD::Bethe(Double_t p,Double_t mass) {
-
-  Double_t mom=p*1000;//MeV
-  Double_t Mass=mass*1000;//Mev
-  Float_t dens =2.33; //g cm-3
-  Double_t K=0.307075;//MeVcm^2/g
-  Double_t ZovA=0.49848;
-  Double_t me=0.511;//MeV/c^2
-  Double_t I=173./1000000.;//MeV
-  Double_t En=TMath::Sqrt(mom*mom+Mass*Mass);//MeV
-  Double_t gamma=En/Mass;
-  Double_t beta=mom/En;
-  Double_t Tmax=2*me*beta*beta*gamma*gamma/(1+2*gamma*me/Mass+(me/Mass)*(me/Mass));
-  Double_t deltaover2=28.816*1e-6*TMath::Sqrt(dens*ZovA)+TMath::Log(beta*gamma)-0.5;
-  Double_t FNor=0.009164; //normalizing to 1 at the minimum of ionization
-
-  return K*ZovA*1/(beta*beta)*(0.5*TMath::Log(2*me*beta*beta*gamma*gamma*Tmax/(I*I))-beta*beta-deltaover2)*2.33*1000*0.03*FNor;
-
+  // returns AliExternalTrackParam::BetheBloch normalized to 1 at the minimum
+  Double_t density=2.33; // g/cm3
+  Double_t thickness=0.03; // cm
+  Double_t meanMIPSi=116.24; // keV in 300 microns of Si
+  Double_t conv=density*1E6*thickness/meanMIPSi;
+  Float_t betagamma=p/mass;
+  return conv*AliExternalTrackParam::BetheBlochSolid(betagamma);
 
 }