A new function for calculating the mean crossed material (A.Dainese, A.Gheata)

diff --git a/STEER/AliKalmanTrack.cxx b/STEER/AliKalmanTrack.cxx
index 8fa770d982a6c9ba2219e05419b6627f5ec13c7e..460e38f4689c5346da0fb0e413c980ccc08bde23 100644 (file)
--- a/STEER/AliKalmanTrack.cxx
+++ b/STEER/AliKalmanTrack.cxx
@@ -164,6 +164,151 @@ void AliKalmanTrack::SetIntegratedTimes(const Double_t *times) {
   for (Int_t i=0; i<AliPID::kSPECIES; i++) fIntegratedTime[i]=times[i];
 }
 
+Double_t AliKalmanTrack::
+MeanMaterialBudgetNew(Double_t *start, Double_t *end, Double_t *mparam) {
+  // 
+  // Calculate mean material budget and material properties between 
+  //    the points "start" and "end".
+  //
+  // "mparam" - parameters used for the energy and multiple scattering
+  //  corrections: 
+  //
+  // mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
+  // mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
+  // mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
+  // mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
+  // mparam[4] - length: sum(x_i) [cm]
+  // mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
+  // mparam[6] - number of boundary crosses
+  //
+
+  mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
+  mparam[4]=0; mparam[5]=0; mparam[6]=0;
+  //
+  Double_t bparam[6]; // total parameters
+  Double_t lparam[6]; // local parameters
+
+  for (Int_t i=0;i<6;i++) bparam[i]=0;
+
+  if (!gGeoManager) {
+    printf("ERROR: no TGeo\n");
+    return 0.;
+  }
+  //
+  Double_t length;
+  Double_t dir[3];
+  length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
+                       (end[1]-start[1])*(end[1]-start[1])+
+                       (end[2]-start[2])*(end[2]-start[2]));
+  mparam[4]=length;
+  if (length<TGeoShape::Tolerance()) return 0.0;
+  Double_t invlen = 1./length;
+  dir[0] = (end[0]-start[0])*invlen;
+  dir[1] = (end[1]-start[1])*invlen;
+  dir[2] = (end[2]-start[2])*invlen;
+
+  // Initialize start point and direction
+  TGeoNode *currentnode = 0;
+  TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
+  //printf("%s length=%f\n",gGeoManager->GetPath(),length);
+  if (!startnode) {
+    printf("ERROR: start point out of geometry\n");
+    return 0.0;
+  }
+  TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
+  lparam[0]   = material->GetDensity();
+  lparam[1]   = material->GetRadLen();
+  lparam[2]   = material->GetA();
+  lparam[3]   = material->GetZ();
+  lparam[4]   = length;
+  lparam[5]   = lparam[3]/lparam[2];
+  if (material->IsMixture()) {
+    TGeoMixture * mixture = (TGeoMixture*)material;
+    lparam[5] =0;
+    Double_t sum =0;
+    for (Int_t iel=0;iel<mixture->GetNelements();iel++){
+      sum  += mixture->GetWmixt()[iel];
+      lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
+    }
+    lparam[5]/=sum;
+  }
+
+  // Locate next boundary within length without computing safety.
+  // Propagate either with length (if no boundary found) or just cross boundary
+  gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
+  Double_t step = 0.0; // Step made
+  Double_t snext = gGeoManager->GetStep();
+  // If no boundary within proposed length, return current density
+  if (!gGeoManager->IsOnBoundary()) {
+    mparam[0] = lparam[0];
+    mparam[1] = lparam[4]/lparam[1];
+    mparam[2] = lparam[2];
+    mparam[3] = lparam[3];
+    mparam[4] = lparam[4];
+    return lparam[0];
+  }
+  // Try to cross the boundary and see what is next
+  Int_t nzero = 0;
+  while (length>TGeoShape::Tolerance()) {
+    currentnode = gGeoManager->GetCurrentNode();
+    if (snext<2.*TGeoShape::Tolerance()) nzero++;
+    else nzero = 0;
+    if (nzero>3) {
+      // This means navigation has problems on one boundary
+      // Try to cross by making a small step
+      printf("ERROR: cannot cross boundary\n");
+      mparam[0] = bparam[0]/step;
+      mparam[1] = bparam[1];
+      mparam[2] = bparam[2]/step;
+      mparam[3] = bparam[3]/step;
+      mparam[5] = bparam[5]/step;
+      mparam[4] = step;
+      mparam[0] = 0.;             // if crash of navigation take mean density 0
+      mparam[1] = 1000000;        // and infinite rad length
+      return bparam[0]/step;
+    }
+    mparam[6]+=1.;
+    step += snext;
+    bparam[1]    += snext/lparam[1];
+    bparam[2]    += snext*lparam[2];
+    bparam[3]    += snext*lparam[3];
+    bparam[5]    += snext*lparam[5];
+    bparam[0]    += snext*lparam[0];
+
+    if (snext>=length) break;
+    if (!currentnode) break;
+    length -= snext;
+    //printf("%s snext=%f length=%f\n", currentnode->GetName(),snext,length);
+    material = currentnode->GetVolume()->GetMedium()->GetMaterial();
+    lparam[0] = material->GetDensity();
+    lparam[1]  = material->GetRadLen();
+    lparam[2]  = material->GetA();
+    lparam[3]  = material->GetZ();
+    //printf("       %f %f %f %f\n",lparam[0],lparam[1],lparam[2],lparam[3]); 
+    lparam[5]   = lparam[3]/lparam[2];
+    if (material->IsMixture()) {
+      TGeoMixture * mixture = (TGeoMixture*)material;
+      lparam[5]=0;
+      Double_t sum =0;
+      for (Int_t iel=0;iel<mixture->GetNelements();iel++){
+        sum+= mixture->GetWmixt()[iel];
+        lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
+      }
+      lparam[5]/=sum;
+    }
+    gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
+    snext = gGeoManager->GetStep();
+    //printf("snext %f\n",snext);
+  }
+  mparam[0] = bparam[0]/step;
+  mparam[1] = bparam[1];
+  mparam[2] = bparam[2]/step;
+  mparam[3] = bparam[3]/step;
+  mparam[5] = bparam[5]/step;
+  return bparam[0]/step;
+}
+
+
 Double_t AliKalmanTrack::MeanMaterialBudget(Double_t *start, Double_t *end, Double_t *mparam)
 {
   // 

diff --git a/STEER/AliKalmanTrack.h b/STEER/AliKalmanTrack.h
index 5e491c454483a09afc36d489abde099c799c9d4b..bc4124fc149f234dd649b396bccae85da924578f 100644 (file)
--- a/STEER/AliKalmanTrack.h
+++ b/STEER/AliKalmanTrack.h
@@ -56,6 +56,8 @@ public:
 
   static 
   Double_t MeanMaterialBudget(Double_t *start,Double_t *end,Double_t *mparam);
+  static Double_t 
+  MeanMaterialBudgetNew(Double_t *start,Double_t *end,Double_t *mparam);
 
   // Time integration (S.Radomski@gsi.de)
   void StartTimeIntegral();