EVGEN/AliGenParam.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 // Class to generate particles from using paramtrized pT and y distributions.
  19 // Distributions are obtained from pointer to object of type AliGenLib.
  20 // (For example AliGenMUONlib)
  21 // Decays are performed using Pythia.
  22 // andreas.morsch@cern.ch
  23
  24 #include "AliGenParam.h"
  25 #include "AliDecayer.h"
  26 #include "AliGenMUONlib.h"
  27 #include "AliRun.h"
  28 #include <TParticle.h>
  29 #include <TParticlePDG.h>
  30 #include <TDatabasePDG.h>
  31 #include <TLorentzVector.h>
  32
  33 #include <TF1.h>
  34 #include <TCanvas.h>
  35 #include <TH1.h>
  36
  37 ClassImp(AliGenParam)
  38
  39 //------------------------------------------------------------
  40
  41   //Begin_Html
  42   /*
  43     <img src="picts/AliGenParam.gif">
  44   */
  45   //End_Html
  46
  47 //____________________________________________________________
  48 //____________________________________________________________
  49 AliGenParam::AliGenParam()
  50 {
  51 // Deafault constructor
  52     fPtPara = 0;
  53     fYPara  = 0;
  54     fParam  = 0;
  55     fAnalog = kAnalog;
  56     SetDeltaPt();
  57     fDecayer = 0;
  58
  59
  60 }
  61
  62 AliGenParam::AliGenParam(Int_t npart, AliGenLib * Library,  Int_t param, char* tname):AliGenMC(npart)
  63 {
  64 // Constructor using number of particles parameterisation id and library
  65     fName = "Param";
  66     fTitle= "Particle Generator using pT and y parameterisation";
  67
  68     fPtParaFunc = Library->GetPt(param, tname);
  69     fYParaFunc  = Library->GetY (param, tname);
  70     fIpParaFunc = Library->GetIp(param, tname);
  71
  72     fPtPara = 0;
  73     fYPara  = 0;
  74     fParam  = param;
  75     fAnalog = kAnalog;
  76     SetForceDecay();
  77     SetDeltaPt();
  78 }
  79
  80 //____________________________________________________________
  81
  82 AliGenParam::AliGenParam(Int_t npart, Int_t param, char* tname):AliGenMC(npart)
  83 {
  84 // Constructor using parameterisation id and number of particles
  85 //
  86     fName = "Param";
  87     fTitle= "Particle Generator using pT and y parameterisation";
  88
  89     AliGenLib* pLibrary = new AliGenMUONlib();
  90
  91     fPtParaFunc = pLibrary->GetPt(param, tname);
  92     fYParaFunc  = pLibrary->GetY (param, tname);
  93     fIpParaFunc = pLibrary->GetIp(param, tname);
  94
  95     fPtPara = 0;
  96     fYPara  = 0;
  97     fParam  = param;
  98     fAnalog = kAnalog;
  99     fChildSelect.Set(5);
 100     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 101     SetForceDecay();
 102     SetCutOnChild();
 103     SetChildMomentumRange();
 104     SetChildPtRange();
 105     SetChildPhiRange();
 106     SetChildThetaRange();
 107     SetDeltaPt();
 108 }
 109
 110 AliGenParam::AliGenParam(Int_t npart, Int_t param,
 111                          Double_t (*PtPara) (Double_t*, Double_t*),
 112                          Double_t (*YPara ) (Double_t* ,Double_t*),
 113                          Int_t    (*IpPara) (TRandom *))
 114     :AliGenMC(npart)
 115 {
 116 // Constructor
 117 // Gines Martinez 1/10/99
 118     fName = "Param";
 119     fTitle= "Particle Generator using pT and y parameterisation";
 120
 121     fPtParaFunc = PtPara;
 122     fYParaFunc  = YPara;
 123     fIpParaFunc = IpPara;
 124 //
 125     fPtPara = 0;
 126     fYPara  = 0;
 127     fParam  = param;
 128     fAnalog = kAnalog;
 129     fChildSelect.Set(5);
 130     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 131     SetForceDecay();
 132     SetCutOnChild();
 133     SetChildMomentumRange();
 134     SetChildPtRange();
 135     SetChildPhiRange();
 136     SetChildThetaRange();
 137     SetDeltaPt();
 138 }
 139
 140
 141 AliGenParam::AliGenParam(const AliGenParam & Param)
 142     :AliGenMC(Param)
 143 {
 144 // Copy constructor
 145     Param.Copy(*this);
 146 }
 147
 148 //____________________________________________________________
 149 AliGenParam::~AliGenParam()
 150 {
 151 // Destructor
 152     delete  fPtPara;
 153     delete  fYPara;
 154 }
 155
 156 //____________________________________________________________
 157 void AliGenParam::Init()
 158 {
 159 // Initialisation
 160
 161     if (gMC) fDecayer = gMC->GetDecayer();
 162   //Begin_Html
 163   /*
 164     <img src="picts/AliGenParam.gif">
 165   */
 166   //End_Html
 167
 168     fPtPara = new TF1("Pt-Parametrization",fPtParaFunc,fPtMin,fPtMax,0);
 169 //  Set representation precision to 10 MeV
 170     Int_t npx= Int_t((fPtMax-fPtMin)/fDeltaPt);
 171
 172     fPtPara->SetNpx(npx);
 173
 174     fYPara  = new TF1("Y -Parametrization",fYParaFunc,fYMin,fYMax,0);
 175     TF1* ptPara = new TF1("Pt-Parametrization",fPtParaFunc,0,15,0);
 176     TF1* yPara  = new TF1("Y -Parametrization",fYParaFunc,-6,6,0);
 177
 178 //
 179 // dN/dy| y=0
 180     Double_t y1=0;
 181     Double_t y2=0;
 182
 183     fdNdy0=fYParaFunc(&y1,&y2);
 184 //
 185 // Integral over generation region
 186     Float_t intYS  = yPara ->Integral(fYMin, fYMax);
 187     Float_t intPt0 = ptPara->Integral(0,15);
 188     Float_t intPtS = ptPara->Integral(fPtMin,fPtMax);
 189     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 190     if (fAnalog == kAnalog) {
 191         fYWgt  = intYS/fdNdy0;
 192         fPtWgt = intPtS/intPt0;
 193         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 194     } else {
 195         fYWgt = intYS/fdNdy0;
 196         fPtWgt = (fPtMax-fPtMin)/intPt0;
 197         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 198     }
 199 //
 200 // particle decay related initialization
 201     fDecayer->SetForceDecay(fForceDecay);
 202     fDecayer->Init();
 203
 204 //
 205     AliGenMC::Init();
 206 }
 207
 208 //____________________________________________________________
 209 void AliGenParam::Generate()
 210 {
 211 //
 212 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 213 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 214 // antineutrons in the the desired theta, phi and momentum windows;
 215 // Gaussian smearing on the vertex is done if selected.
 216 // The decay of heavy mesons is done using lujet,
 217 //    and the childern particle are tracked by GEANT
 218 // However, light mesons are directly tracked by GEANT
 219 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 220 //
 221 //
 222 //  Reinitialize decayer
 223     fDecayer->Init();
 224 //
 225   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 226   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 227   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 228   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 229   Float_t p[3], pc[3],
 230           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 231   Double_t ty, xmt;
 232   Int_t nt, i, j;
 233   Float_t  wgtp, wgtch;
 234   Double_t dummy;
 235   static TClonesArray *particles;
 236   //
 237   if(!particles) particles = new TClonesArray("TParticle",1000);
 238
 239   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 240   //
 241   Float_t random[6];
 242
 243 // Calculating vertex position per event
 244   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 245   if(fVertexSmear==kPerEvent) {
 246       Vertex();
 247       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 248   }
 249
 250   Int_t ipa=0;
 251
 252 // Generating fNpart particles
 253   while (ipa<fNpart) {
 254       while(1) {
 255 //
 256 // particle type
 257           Int_t iPart = fIpParaFunc(fRandom);
 258           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 259           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 260           Float_t am = particle->Mass();
 261
 262           Rndm(random,2);
 263 //
 264 // phi
 265           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 266 //
 267 // y
 268           ty = TMath::TanH(fYPara->GetRandom());
 269 //
 270 // pT
 271           if (fAnalog == kAnalog) {
 272               pt=fPtPara->GetRandom();
 273               wgtp=fParentWeight;
 274               wgtch=fChildWeight;
 275           } else {
 276               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 277               Double_t ptd=pt;
 278               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 279               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 280           }
 281           xmt=sqrt(pt*pt+am*am);
 282           if (TMath::Abs(ty)==1.) {
 283               ty=0.;
 284               Fatal("AliGenParam",
 285                     "Division by 0: Please check you rapidity range !");
 286           }
 287
 288           pl=xmt*ty/sqrt(1.-ty*ty);
 289           theta=TMath::ATan2(pt,pl);
 290 // Cut on theta
 291           if(theta<fThetaMin || theta>fThetaMax) continue;
 292           ptot=TMath::Sqrt(pt*pt+pl*pl);
 293 // Cut on momentum
 294           if(ptot<fPMin || ptot>fPMax) continue;
 295 //
 296           p[0]=pt*TMath::Cos(phi);
 297           p[1]=pt*TMath::Sin(phi);
 298           p[2]=pl;
 299           if(fVertexSmear==kPerTrack) {
 300               Rndm(random,6);
 301               for (j=0;j<3;j++) {
 302                   origin0[j]=
 303                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 304                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 305               }
 306           }
 307
 308 // Looking at fForceDecay :
 309 // if fForceDecay != none Primary particle decays using
 310 // AliPythia and children are tracked by GEANT
 311 //
 312 // if fForceDecay == none Primary particle is tracked by GEANT
 313 // (In the latest, make sure that GEANT actually does all the decays you want)
 314 //
 315
 316           if (fForceDecay != kNoDecay) {
 317 // Using lujet to decay particle
 318               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 319               TLorentzVector pmom(p[0], p[1], p[2], energy);
 320               fDecayer->Decay(iPart,&pmom);
 321 //
 322 // select decay particles
 323               Int_t np=fDecayer->ImportParticles(particles);
 324
 325               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 326               if (fGeometryAcceptance)
 327                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 328               Int_t ncsel=0;
 329               Int_t* pFlag      = new Int_t[np];
 330               Int_t* pParent    = new Int_t[np];
 331               Int_t* pSelected  = new Int_t[np];
 332               Int_t* trackIt    = new Int_t[np];
 333
 334               for (i=0; i<np; i++) {
 335                   pFlag[i]     =  0;
 336                   pSelected[i] =  0;
 337                   pParent[i]   = -1;
 338               }
 339
 340               if (np >1) {
 341                   TParticle* iparticle =  (TParticle *) particles->At(0);
 342                   Int_t ipF, ipL;
 343                   for (i = 1; i<np ; i++) {
 344                       trackIt[i] = 1;
 345                       iparticle = (TParticle *) particles->At(i);
 346                       Int_t kf = iparticle->GetPdgCode();
 347                       Int_t ks = iparticle->GetStatusCode();
 348 // flagged particle
 349
 350                       if (pFlag[i] == 1) {
 351                           ipF = iparticle->GetFirstDaughter();
 352                           ipL = iparticle->GetLastDaughter();
 353                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 354                           continue;
 355                       }
 356
 357 // flag decay products of particles with long life-time (c tau > .3 mum)
 358
 359                       if (ks != 1) {
 360 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 361
 362                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 363 //                        Double_t mass     = particle->Mass();
 364 //                        Double_t width    = particle->Width();
 365                           if (lifeTime > (Double_t) fMaxLifeTime) {
 366                               ipF = iparticle->GetFirstDaughter();
 367                               ipL = iparticle->GetLastDaughter();
 368                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 369                           } else{
 370                               trackIt[i]     = 0;
 371                               pSelected[i]   = 1;
 372                           }
 373                       } // ks==1 ?
 374 //
 375 // children
 376
 377                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 378                       {
 379                           if (fCutOnChild) {
 380                               pc[0]=iparticle->Px();
 381                               pc[1]=iparticle->Py();
 382                               pc[2]=iparticle->Pz();
 383                               Bool_t  childok = KinematicSelection(iparticle, 1);
 384                               if(childok) {
 385                                   pSelected[i]  = 1;
 386                                   ncsel++;
 387                               } else {
 388                                   ncsel=-1;
 389                                   break;
 390                               } // child kine cuts
 391                           } else {
 392                               pSelected[i]  = 1;
 393                               ncsel++;
 394                           } // if child selection
 395                       } // select muon
 396                   } // decay particle loop
 397               } // if decay products
 398
 399               Int_t iparent;
 400               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 401                   ipa++;
 402 //
 403 // Parent
 404                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 405                   pParent[0] = nt;
 406                   KeepTrack(nt);
 407 //
 408 // Decay Products
 409 //
 410                   for (i = 1; i < np; i++) {
 411                       if (pSelected[i]) {
 412                           TParticle* iparticle = (TParticle *) particles->At(i);
 413                           Int_t kf  = iparticle->GetPdgCode();
 414                           Int_t ipa = iparticle->GetFirstMother()-1;
 415
 416                           och[0] = origin0[0]+iparticle->Vx()/10;
 417                           och[1] = origin0[1]+iparticle->Vy()/10;
 418                           och[2] = origin0[2]+iparticle->Vz()/10;
 419                           pc[0]  = iparticle->Px();
 420                           pc[1]  = iparticle->Py();
 421                           pc[2]  = iparticle->Pz();
 422
 423                           if (ipa > -1) {
 424                               iparent = pParent[ipa];
 425                           } else {
 426                               iparent = -1;
 427                           }
 428
 429                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 430                                            pc, och, polar,
 431                                            0, kPDecay, nt, wgtch);
 432                           pParent[i] = nt;
 433                           KeepTrack(nt);
 434                       } // Selected
 435                   } // Particle loop
 436               }  // Decays by Lujet
 437               particles->Clear();
 438               if (pFlag)      delete[] pFlag;
 439               if (pParent)    delete[] pParent;
 440               if (pSelected)  delete[] pSelected;
 441               if (trackIt)    delete[] trackIt;
 442           } // kinematic selection
 443           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 444           {
 445             gAlice->
 446                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 447             ipa++;
 448           }
 449           break;
 450     } // while
 451   } // event loop
 452   SetHighWaterMark(nt);
 453 }
 454
 455 void AliGenParam::Draw()
 456 {
 457     //
 458     // Draw the pT and y Distributions
 459     //
 460      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 461      c0->Divide(2,1);
 462      c0->cd(1);
 463      fPtPara->Draw();
 464      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 465      c0->cd(2);
 466      fYPara->Draw();
 467      fYPara->GetHistogram()->SetXTitle("y");
 468 }
 469
 470 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 471 {
 472 // Assignment operator
 473     rhs.Copy(*this);
 474     return *this;
 475 }
 476
 477
 478