EVGEN/AliGenHalo.cxx

   1 /**************************************************************************
   2  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3  *                                                                        *
   4  * Author: The ALICE Off-line Project.                                    *
   5  * Contributors are mentioned in the code where appropriate.              *
   6  *                                                                        *
   7  * Permission to use, copy, modify and distribute this software and its   *
   8  * documentation strictly for non-commercial purposes is hereby granted   *
   9  * without fee, provided that the above copyright notice appears in all   *
  10  * copies and that both the copyright notice and this permission notice   *
  11  * appear in the supporting documentation. The authors make no claims     *
  12  * about the suitability of this software for any purpose. It is          *
  13  * provided "as is" without express or implied warranty.                  *
  14  **************************************************************************/
  15
  16 /* $Id$ */
  17
  18 // Read background particles from a boundary source
  19 // Very specialized generator to simulate background from beam halo.
  20 // The input file is a text file specially prepared
  21 // for this purpose.
  22 // Author: andreas.morsch@cern.ch
  23
  24 #include <stdlib.h>
  25
  26 #include <TDatabasePDG.h>
  27 #include <TPDGCode.h>
  28
  29 #include "AliGenHalo.h"
  30 #include "AliRun.h"
  31
  32 ClassImp(AliGenHalo)
  33
  34 AliGenHalo::AliGenHalo()
  35     :AliGenerator(-1),
  36      fp(0),
  37      fFileName(0)
  38 {
  39 // Constructor
  40     fName="Halo";
  41     fTitle="Halo from LHC Tunnel";
  42 //
  43 //  Read all particles
  44     fNpart=-1;
  45 }
  46
  47 AliGenHalo::AliGenHalo(Int_t npart)
  48     :AliGenerator(npart),
  49      fp(0),
  50      fFileName(0)
  51 {
  52 // Constructor
  53     fName="Halo";
  54     fTitle="Halo from LHC Tunnel";
  55 //
  56 //  Read all particles
  57     fNpart=-1;
  58 }
  59
  60 //____________________________________________________________
  61 AliGenHalo::~AliGenHalo()
  62 {
  63 // Destructor
  64 }
  65
  66 //____________________________________________________________
  67 void AliGenHalo::Init()
  68 {
  69 // Initialisation
  70 }
  71
  72 //____________________________________________________________
  73 void AliGenHalo::Generate()
  74 {
  75 // Generate from input file
  76     fp = fopen(fFileName,"r");
  77     if (fp) {
  78         printf("\n File %s opened for reading ! \n ", (char*) &fFileName);
  79     } else {
  80         printf("\n Opening of file %s failed ! \n ",  (char*) &fFileName);
  81     }
  82 //
  83 // MARS particle codes
  84   const Int_t kmars[12]={0,kProton,kNeutron,kPiPlus,kPiMinus,kKPlus,kKMinus,
  85                          kMuonPlus,kMuonMinus,kGamma,kElectron,kPositron};
  86
  87   Float_t polar[3]= {0,0,0};
  88   Float_t origin[3];
  89   Float_t p[3], p0;
  90   Float_t ekin, wgt, tx, ty, tz, txy;
  91   Float_t amass;
  92   //
  93   Int_t ipart, ncols, nt;
  94
  95   Int_t nread=0;
  96   origin[2]=2650;
  97
  98   while(1) {
  99       ncols = fscanf(fp,"%i %f %f %f %f %f %f",
 100                      &ipart, &ekin, &wgt,
 101                      &origin[0], &origin[1],
 102                      &tx, &ty);
 103       if (ncols < 0) break;
 104       nread++;
 105       if (fNpart !=-1 && nread > fNpart) break;
 106       ipart = kmars[ipart];
 107       amass = TDatabasePDG::Instance()->GetParticle(ipart)->Mass();
 108       p0=sqrt(ekin*ekin + 2.*amass);
 109
 110       txy=TMath::Sqrt(tx*tx+ty*ty);
 111       if (txy == 1.) {
 112           tz=0;
 113       } else {
 114           tz=-TMath::Sqrt(1.-txy);
 115       }
 116       p[0]=p0*tx;
 117       p[1]=p0*ty;
 118       p[2]=p0*tz;
 119       fParentWeight=wgt;
 120       PushTrack(fTrackIt,-1,ipart,p,origin,polar,0,kPNoProcess,nt,fParentWeight);
 121 //    PushTrack(fTrackIt,-1,ipart,p,origin,polar,0,"Halo+",nt,fParentWeight);
 122       origin[2]=-origin[2];
 123       p[2]=-p[2];
 124       PushTrack(fTrackIt,-1,ipart,p,origin,polar,0,kPNoProcess,nt,fParentWeight);
 125 //    PushTrack(fTrackIt,-1,ipart,p,origin,polar,0,"Halo-",nt,fParentWeight);
 126       origin[2]=-origin[2];
 127       p[2]=-p[2];
 128   }
 129 }
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