EVGEN/AliGenParam.cxx

   1 #include "AliGenParam.h"
   2 #include "AliGenMUONlib.h"
   3 #include "AliRun.h"
   4 #include "AliPythia.h"
   5 #include <TDirectory.h>
   6 #include <TFile.h>
   7 #include <TTree.h>
   8 #include <stdlib.h>
   9 #include <TParticle.h>
  10
  11 ClassImp(AliGenParam)
  12
  13 //------------------------------------------------------------
  14
  15   //Begin_Html
  16   /*
  17     <img src="picts/AliGenParam.gif">
  18   */
  19   //End_Html
  20
  21 //____________________________________________________________
  22 //____________________________________________________________
  23 AliGenParam::AliGenParam()
  24                  :AliGenerator()
  25 {
  26   fPtPara = 0;
  27   fYPara  = 0;
  28   fParam  = jpsi_p;
  29   fAnalog = analog;
  30   SetCutOnChild();
  31 }
  32
  33 //____________________________________________________________
  34 AliGenParam::AliGenParam(Int_t npart, Param_t param)
  35 //                                 Double_t (*PtPara)(Double_t*, Double_t*),
  36 //                                 Double_t (*YPara) (Double_t* ,Double_t*))
  37     :AliGenerator(npart)
  38 {
  39   //
  40   //  fName="HMESONpara";
  41   //  fTitle="Heavy Mesons Parametrisation";
  42   fPtParaFunc = AliGenMUONlib::GetPt(param);
  43   fYParaFunc  = AliGenMUONlib::GetY(param);
  44   fIpParaFunc = AliGenMUONlib::GetIp(param);
  45
  46   fPtPara = 0;
  47   fYPara  = 0;
  48   fParam  = param;
  49   fAnalog = analog;
  50   fChildSelect.Set(5);
  51   for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
  52   ForceDecay();
  53   SetCutOnChild();
  54 }
  55
  56 //____________________________________________________________
  57 AliGenParam::~AliGenParam()
  58 {
  59     delete  fPtPara;
  60     delete  fYPara;
  61 }
  62
  63 //____________________________________________________________
  64 void AliGenParam::Init()
  65 {
  66     SetMC(new AliPythia());
  67     fPythia= (AliPythia*) fgMCEvGen;
  68
  69 //  End of the test !!!
  70   //Begin_Html
  71   /*
  72     <img src="picts/AliGenParam.gif">
  73   */
  74   //End_Html
  75
  76   fPtPara = new TF1("Pt-Parametrization",fPtParaFunc,fPtMin,fPtMax,0);
  77   fYPara  = new TF1("Y -Parametrization",fYParaFunc,fYMin,fYMax,0);
  78   TF1* PtPara = new TF1("Pt-Parametrization",fPtParaFunc,0,15,0);
  79   TF1* YPara  = new TF1("Y -Parametrization",fYParaFunc,-6,6,0);
  80
  81 //
  82 // dN/dy| y=0
  83   Double_t y1=0;
  84   Double_t y2=0;
  85
  86   fdNdy0=fYParaFunc(&y1,&y2);
  87 //
  88 // Integral over generation region
  89   Float_t IntYS  = YPara ->Integral(fYMin, fYMax);
  90   Float_t IntPt0 = PtPara->Integral(0,15);
  91   Float_t IntPtS = PtPara->Integral(fPtMin,fPtMax);
  92   Float_t PhiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
  93   if (fAnalog == analog) {
  94      fYWgt  = IntYS/fdNdy0;
  95      fPtWgt = IntPtS/IntPt0;
  96      fParentWeight = fYWgt*fPtWgt*PhiWgt/fNpart;
  97   } else {
  98       fYWgt = IntYS/fdNdy0;
  99       fPtWgt = (fPtMax-fPtMin)/IntPt0;
 100       fParentWeight = fYWgt*fPtWgt*PhiWgt/fNpart;
 101   }
 102 //
 103 // particle decay related initialization
 104   fPythia->DefineParticles();
 105 // semimuonic decays of charm and beauty
 106   fPythia->ForceDecay(fForceDecay);
 107 //
 108     switch (fForceDecay)
 109     {
 110     case semielectronic:
 111     case dielectron:
 112     case b_jpsi_dielectron:
 113     case b_psip_dielectron:
 114         fChildSelect[0]=11;
 115         break;
 116     case semimuonic:
 117     case dimuon:
 118     case b_jpsi_dimuon:
 119     case b_psip_dimuon:
 120         fChildSelect[0]=13;
 121         break;
 122     case pitomu:
 123         fChildSelect[0]=13;
 124         break;
 125     case katomu:
 126         fChildSelect[0]=13;
 127         break;
 128     }
 129
 130 }
 131
 132 //____________________________________________________________
 133 void AliGenParam::Generate()
 134 {
 135 // Generate 'npart' of heavy mesons (J/Psi, upsilon or phi) in the
 136 // the desired theta, phi and momentum windows; Gaussian smearing
 137 // on the vertex is done if selected
 138
 139
 140   //printf("Generate !!!!!!!!!!!!!\n");
 141
 142   Float_t polar[3]= {0,0,0};
 143   //
 144   Float_t origin[3], origin0[3];
 145   Float_t pt, pl, ptot;
 146   Float_t phi, theta;
 147   Float_t p[3], pc[3], och[3], pch[10][3];
 148   Float_t ty, xmt;
 149   Int_t nt, i, j, kfch[10];
 150   Float_t  wgtp, wgtch;
 151   Double_t dummy;
 152   static TClonesArray *particles;
 153   //
 154   if(!particles) particles=new TClonesArray("TParticle",1000);
 155   //
 156   Float_t random[6];
 157   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 158   if(fVertexSmear==perEvent) {
 159       gMC->Rndm(random,6);
 160       for (j=0;j<3;j++) {
 161           origin0[j]+=fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 162               TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 163       }
 164   }
 165   Int_t ipa=0;
 166   while (ipa<fNpart) {
 167     while(1) {
 168 //
 169 // particle type
 170           Int_t Ipart = fIpParaFunc();
 171           fChildWeight=(fPythia->GetBraPart(Ipart))*fParentWeight;
 172           Float_t am=fPythia->GetPMAS(fPythia->LuComp(Ipart),1);
 173           gMC->Rndm(random,2);
 174 //
 175 // phi
 176           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 177 //
 178 // y
 179           ty=Float_t(TMath::TanH(fYPara->GetRandom()));
 180 //
 181 // pT
 182           if (fAnalog == analog) {
 183               pt=fPtPara->GetRandom();
 184               wgtp=fParentWeight;
 185               wgtch=fChildWeight;
 186           } else {
 187               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 188               Double_t ptd=pt;
 189               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 190               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 191           }
 192           xmt=sqrt(pt*pt+am*am);
 193           pl=xmt*ty/sqrt(1.-ty*ty);
 194           theta=TMath::ATan2(pt,pl);
 195           if(theta<fThetaMin || theta>fThetaMax) continue;
 196           ptot=TMath::Sqrt(pt*pt+pl*pl);
 197           if(ptot<fPMin || ptot>fPMax) continue;
 198           p[0]=pt*TMath::Cos(phi);
 199           p[1]=pt*TMath::Sin(phi);
 200           p[2]=pl;
 201           if(fVertexSmear==perTrack) {
 202               gMC->Rndm(random,6);
 203               for (j=0;j<3;j++) {
 204                   origin0[j]=
 205                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 206                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 207               }
 208           }
 209 //
 210 // use lujet to decay particle
 211
 212           Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 213           fPythia->DecayParticle(Ipart,energy,theta,phi);
 214           //      fPythia->LuList(1);
 215
 216
 217           //printf("origin0 %f %f %f\n",origin0[0],origin0[1],origin0[2]);
 218           //printf("fCutOnChild %d \n",fCutOnChild);
 219 //
 220 // select muons
 221           Int_t np=fPythia->ImportParticles(particles,"All");
 222           //printf("np     %d \n",np);
 223           Int_t ncsel=0;
 224           for (i = 1; i<np; i++) {
 225               TParticle *  iparticle = (TParticle *) particles->At(i);
 226               Int_t kf = iparticle->GetPdgCode();
 227               //printf("kf %d\n",kf);
 228 //
 229 // children
 230               if (ChildSelected(TMath::Abs(kf)))
 231               {
 232                   pc[0]=iparticle->Px();
 233                   pc[1]=iparticle->Py();
 234                   pc[2]=iparticle->Pz();
 235                   och[0]=origin0[0]+iparticle->Vx()/10;
 236                   och[1]=origin0[1]+iparticle->Vy()/10;
 237                   och[2]=origin0[2]+iparticle->Vz()/10;
 238                   if (fCutOnChild) {
 239                     Float_t PtChild=TMath::Sqrt(pc[0]*pc[0]+pc[1]*pc[1]);
 240                     Float_t PChild=TMath::Sqrt(PtChild*PtChild+pc[2]*pc[2]);
 241                     Float_t ThetaChild=TMath::ATan2(PtChild,pc[2]);
 242                     Float_t PhiChild=TMath::ATan2(pc[1],pc[0])+TMath::Pi();
 243                     Bool_t childok =
 244                       ((PtChild   > fPtMin   && PtChild   <fPtMax)      &&
 245                         (PChild    > fPMin    && PChild    <fPMax)       &&
 246                         (ThetaChild>fThetaMin && ThetaChild<fThetaMax)   &&
 247                         (PhiChild  >  fPhiMin && PhiChild  <fPhiMax));
 248                     if(childok)
 249                       {
 250                         pch[ncsel][0]=pc[0];
 251                         pch[ncsel][1]=pc[1];
 252                         pch[ncsel][2]=pc[2];
 253                         kfch[ncsel]=kf;
 254                         ncsel++;
 255                       } else {
 256                         ncsel=-1;
 257                         break;
 258                       } // child kine cuts
 259                   } else {
 260                     pch[ncsel][0]=pc[0];
 261                     pch[ncsel][1]=pc[1];
 262                     pch[ncsel][2]=pc[2];
 263                     kfch[ncsel]=kf;
 264                     ncsel++;
 265                   } // if child selection
 266               } // select muon
 267           } // decay particle loop
 268           Int_t iparent;
 269           if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 270               ipa++;
 271 //
 272 // parent
 273               gAlice->
 274                   SetTrack(0,-1,Ipart,p,origin,polar,0,"Primary",nt,wgtp);
 275               iparent=nt;
 276
 277               for (i=0; i< ncsel; i++) {
 278                   gAlice->SetTrack(fTrackIt,iparent,kfch[i],
 279                                    &pch[i][0],och,polar,
 280                                    0,"Decay",nt,wgtch);
 281                   gAlice->KeepTrack(nt);
 282               }
 283
 284           } // kinematic selection
 285           break;
 286     } // while
 287   } // event loop
 288 }
 289
 290 Bool_t AliGenParam::ChildSelected(Int_t ip)
 291 {
 292     for (Int_t i=0; i<5; i++)
 293     {
 294         if (fChildSelect[i]==ip) return kTRUE;
 295     }
 296     return kFALSE;
 297 }
 298
 299 Bool_t AliGenParam::KinematicSelection(TParticle *particle)
 300 {
 301     Float_t px=particle->Px();
 302     Float_t py=particle->Py();
 303     Float_t pz=particle->Pz();
 304 //
 305 // momentum cut
 306     Float_t p=TMath::Sqrt(px*px+py*py+pz*pz);
 307     if (p > fPMax || p < fPMin)
 308     {
 309 //      printf("\n failed p cut %f %f %f \n",p,fPMin,fPMax);
 310         return kFALSE;
 311     }
 312     Float_t pt=TMath::Sqrt(px*px+py*py);
 313
 314 //
 315 // theta cut
 316     Float_t  theta = Float_t(TMath::ATan2(Double_t(pt),Double_t(p)));
 317     if (theta > fThetaMax || theta < fThetaMin)
 318     {
 319 //      printf("\n failed theta cut %f %f %f \n",theta,fThetaMin,fThetaMax);
 320         return kFALSE;
 321     }
 322
 323     return kTRUE;
 324 }
 325
 326
 327
 328