X-Git-Url: http://git.uio.no/git/?a=blobdiff_plain;f=ITS%2FAliITSpidESD.cxx;h=4c6c0572e34de4d8d1638f63c62b09f6c5f78030;hb=b89be497ffcbeed9d2347e8de59d0586836e82d4;hp=b058f043e8dd6b60aea45c56b9249080f4ce6162;hpb=ca75fe5f3369103e85e13d37ef59e3b2eb619804;p=u%2Fmrichter%2FAliRoot.git

diff --git a/ITS/AliITSpidESD.cxx b/ITS/AliITSpidESD.cxx
index b058f043e8d..4c6c0572e34 100644
--- a/ITS/AliITSpidESD.cxx
+++ b/ITS/AliITSpidESD.cxx
@@ -13,71 +13,36 @@
  * provided "as is" without express or implied warranty.                  *
  **************************************************************************/
 
+/* $Id$ */
+
 //-----------------------------------------------------------------
 //           Implementation of the ITS PID class
 // Very naive one... Should be made better by the detector experts...
 //      Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
 //-----------------------------------------------------------------
 
+#include <TMath.h>
+
 #include "AliITSpidESD.h"
-#include "AliESD.h"
 #include "AliESDtrack.h"
+#include "AliExternalTrackParam.h"
 
 ClassImp(AliITSpidESD)
 
-//_________________________________________________________________________
-AliITSpidESD::AliITSpidESD(Double_t *param)
-{
-  //
-  //  The main constructor
-  //
-  fMIP=param[0];
-  fRes=param[1];
-  fRange=param[2];
-}
 
-Double_t AliITSpidESD::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<3.5) 
-     bethe=(1.+ bg2)/bg2*(log(5940*bg2) - bg2/(1.+ bg2));
-  else*/  // not 100% clear why...
-     bethe=(1.+ bg2)/bg2*(log(3.5*5940*bg) - bg2/(1.+ bg2));
-  return bethe/11.091;
+//______________________________________________________________________
+AliITSpidESD::AliITSpidESD():TObject(){
+  //Default constructor
+ 
 }
 
-//_________________________________________________________________________
-Int_t AliITSpidESD::MakePID(AliESD *event)
-{
-  //
-  //  This function calculates the "detector response" PID probabilities 
-  //
-  static const Double_t masses[]={
-    0.000511, 0.105658, 0.139570, 0.493677, 0.938272, 1.875613
-  };
-  Int_t ntrk=event->GetNumberOfTracks();
-  for (Int_t i=0; i<ntrk; i++) {
-    AliESDtrack *t=event->GetTrack(i);
-    if ((t->GetStatus()&AliESDtrack::kITSin )==0)
-      if ((t->GetStatus()&AliESDtrack::kITSout)==0) continue;
-    Double_t mom=t->GetP();
-    Double_t dedx=t->GetITSsignal()/fMIP;
-    Int_t ns=AliESDtrack::kSPECIES;
-    Double_t p[10];
-    for (Int_t j=0; j<ns; j++) {
-      Double_t mass=masses[j];
-      Double_t bethe=Bethe(mom/mass); 
-      Double_t sigma=fRes*bethe;
-      if (TMath::Abs(dedx-bethe) > fRange*sigma) {
-	p[j]=TMath::Exp(-0.5*fRange*fRange)/sigma;
-        continue;
-      }
-      p[j]=TMath::Exp(-0.5*(dedx-bethe)*(dedx-bethe)/(sigma*sigma))/sigma;
-    }
-    t->SetITSpid(p);
-  }
-  return 0;
+Double_t AliITSpidESD::Bethe(Double_t p,Double_t mass) {
+  // 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);
+
 }