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 {
 143 // copy constructor
 144     Param.Copy(*this);
 145 }
 146
 147 //____________________________________________________________
 148 AliGenParam::~AliGenParam()
 149 {
 150 // Destructor
 151     delete  fPtPara;
 152     delete  fYPara;
 153 }
 154
 155 //____________________________________________________________
 156 void AliGenParam::Init()
 157 {
 158 // Initialisation
 159
 160     if (gMC) fDecayer = gMC->GetDecayer();
 161   //Begin_Html
 162   /*
 163     <img src="picts/AliGenParam.gif">
 164   */
 165   //End_Html
 166
 167     fPtPara = new TF1("Pt-Parametrization",fPtParaFunc,fPtMin,fPtMax,0);
 168 //  Set representation precision to 10 MeV
 169     Int_t npx= Int_t((fPtMax-fPtMin)/fDeltaPt);
 170
 171     fPtPara->SetNpx(npx);
 172
 173     fYPara  = new TF1("Y -Parametrization",fYParaFunc,fYMin,fYMax,0);
 174     TF1* ptPara = new TF1("Pt-Parametrization",fPtParaFunc,0,15,0);
 175     TF1* yPara  = new TF1("Y -Parametrization",fYParaFunc,-6,6,0);
 176
 177 //
 178 // dN/dy| y=0
 179     Double_t y1=0;
 180     Double_t y2=0;
 181
 182     fdNdy0=fYParaFunc(&y1,&y2);
 183 //
 184 // Integral over generation region
 185     Float_t intYS  = yPara ->Integral(fYMin, fYMax);
 186     Float_t intPt0 = ptPara->Integral(0,15);
 187     Float_t intPtS = ptPara->Integral(fPtMin,fPtMax);
 188     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 189     if (fAnalog == kAnalog) {
 190         fYWgt  = intYS/fdNdy0;
 191         fPtWgt = intPtS/intPt0;
 192         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 193     } else {
 194         fYWgt = intYS/fdNdy0;
 195         fPtWgt = (fPtMax-fPtMin)/intPt0;
 196         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 197     }
 198 //
 199 // particle decay related initialization
 200     fDecayer->SetForceDecay(fForceDecay);
 201     fDecayer->Init();
 202
 203 //
 204     AliGenMC::Init();
 205 }
 206
 207 //____________________________________________________________
 208 void AliGenParam::Generate()
 209 {
 210 //
 211 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 212 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 213 // antineutrons in the the desired theta, phi and momentum windows;
 214 // Gaussian smearing on the vertex is done if selected.
 215 // The decay of heavy mesons is done using lujet,
 216 //    and the childern particle are tracked by GEANT
 217 // However, light mesons are directly tracked by GEANT
 218 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 219 //
 220 //
 221 //  Reinitialize decayer
 222     fDecayer->Init();
 223 //
 224   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 225   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 226   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 227   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 228   Float_t p[3], pc[3],
 229           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 230   Double_t ty, xmt;
 231   Int_t nt, i, j;
 232   Float_t  wgtp, wgtch;
 233   Double_t dummy;
 234   static TClonesArray *particles;
 235   //
 236   if(!particles) particles = new TClonesArray("TParticle",1000);
 237
 238   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 239   //
 240   Float_t random[6];
 241
 242 // Calculating vertex position per event
 243   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 244   if(fVertexSmear==kPerEvent) {
 245       Vertex();
 246       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 247   }
 248
 249   Int_t ipa=0;
 250
 251 // Generating fNpart particles
 252   while (ipa<fNpart) {
 253       while(1) {
 254 //
 255 // particle type
 256           Int_t iPart = fIpParaFunc(fRandom);
 257           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 258           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 259           Float_t am = particle->Mass();
 260
 261           Rndm(random,2);
 262 //
 263 // phi
 264           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 265 //
 266 // y
 267           ty = TMath::TanH(fYPara->GetRandom());
 268 //
 269 // pT
 270           if (fAnalog == kAnalog) {
 271               pt=fPtPara->GetRandom();
 272               wgtp=fParentWeight;
 273               wgtch=fChildWeight;
 274           } else {
 275               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 276               Double_t ptd=pt;
 277               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 278               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 279           }
 280           xmt=sqrt(pt*pt+am*am);
 281           if (TMath::Abs(ty)==1.) {
 282               ty=0.;
 283               Fatal("AliGenParam",
 284                     "Division by 0: Please check you rapidity range !");
 285           }
 286
 287           pl=xmt*ty/sqrt(1.-ty*ty);
 288           theta=TMath::ATan2(pt,pl);
 289 // Cut on theta
 290           if(theta<fThetaMin || theta>fThetaMax) continue;
 291           ptot=TMath::Sqrt(pt*pt+pl*pl);
 292 // Cut on momentum
 293           if(ptot<fPMin || ptot>fPMax) continue;
 294 //
 295           p[0]=pt*TMath::Cos(phi);
 296           p[1]=pt*TMath::Sin(phi);
 297           p[2]=pl;
 298           if(fVertexSmear==kPerTrack) {
 299               Rndm(random,6);
 300               for (j=0;j<3;j++) {
 301                   origin0[j]=
 302                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 303                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 304               }
 305           }
 306
 307 // Looking at fForceDecay :
 308 // if fForceDecay != none Primary particle decays using
 309 // AliPythia and children are tracked by GEANT
 310 //
 311 // if fForceDecay == none Primary particle is tracked by GEANT
 312 // (In the latest, make sure that GEANT actually does all the decays you want)
 313 //
 314
 315           if (fForceDecay != kNoDecay) {
 316 // Using lujet to decay particle
 317               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 318               TLorentzVector pmom(p[0], p[1], p[2], energy);
 319               fDecayer->Decay(iPart,&pmom);
 320 //
 321 // select decay particles
 322               Int_t np=fDecayer->ImportParticles(particles);
 323
 324               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 325               if (fGeometryAcceptance)
 326                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 327               Int_t ncsel=0;
 328               Int_t* pFlag      = new Int_t[np];
 329               Int_t* pParent    = new Int_t[np];
 330               Int_t* pSelected  = new Int_t[np];
 331               Int_t* trackIt    = new Int_t[np];
 332
 333               for (i=0; i<np; i++) {
 334                   pFlag[i]     =  0;
 335                   pSelected[i] =  0;
 336                   pParent[i]   = -1;
 337               }
 338
 339               if (np >1) {
 340                   TParticle* iparticle =  (TParticle *) particles->At(0);
 341                   Int_t ipF, ipL;
 342                   for (i = 1; i<np ; i++) {
 343                       trackIt[i] = 1;
 344                       iparticle = (TParticle *) particles->At(i);
 345                       Int_t kf = iparticle->GetPdgCode();
 346                       Int_t ks = iparticle->GetStatusCode();
 347 // flagged particle
 348
 349                       if (pFlag[i] == 1) {
 350                           ipF = iparticle->GetFirstDaughter();
 351                           ipL = iparticle->GetLastDaughter();
 352                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 353                           continue;
 354                       }
 355
 356 // flag decay products of particles with long life-time (c tau > .3 mum)
 357
 358                       if (ks != 1) {
 359 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 360
 361                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 362 //                        Double_t mass     = particle->Mass();
 363 //                        Double_t width    = particle->Width();
 364                           if (lifeTime > (Double_t) fMaxLifeTime) {
 365                               ipF = iparticle->GetFirstDaughter();
 366                               ipL = iparticle->GetLastDaughter();
 367                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 368                           } else{
 369                               trackIt[i]     = 0;
 370                               pSelected[i]   = 1;
 371                           }
 372                       } // ks==1 ?
 373 //
 374 // children
 375
 376                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 377                       {
 378                           if (fCutOnChild) {
 379                               pc[0]=iparticle->Px();
 380                               pc[1]=iparticle->Py();
 381                               pc[2]=iparticle->Pz();
 382                               Bool_t  childok = KinematicSelection(iparticle, 1);
 383                               if(childok) {
 384                                   pSelected[i]  = 1;
 385                                   ncsel++;
 386                               } else {
 387                                   ncsel=-1;
 388                                   break;
 389                               } // child kine cuts
 390                           } else {
 391                               pSelected[i]  = 1;
 392                               ncsel++;
 393                           } // if child selection
 394                       } // select muon
 395                   } // decay particle loop
 396               } // if decay products
 397
 398               Int_t iparent;
 399               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 400                   ipa++;
 401 //
 402 // Parent
 403                   SetTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 404                   pParent[0] = nt;
 405                   KeepTrack(nt);
 406 //
 407 // Decay Products
 408 //
 409                   for (i = 1; i < np; i++) {
 410                       if (pSelected[i]) {
 411                           TParticle* iparticle = (TParticle *) particles->At(i);
 412                           Int_t kf  = iparticle->GetPdgCode();
 413                           Int_t ipa = iparticle->GetFirstMother()-1;
 414
 415                           och[0] = origin0[0]+iparticle->Vx()/10;
 416                           och[1] = origin0[1]+iparticle->Vy()/10;
 417                           och[2] = origin0[2]+iparticle->Vz()/10;
 418                           pc[0]  = iparticle->Px();
 419                           pc[1]  = iparticle->Py();
 420                           pc[2]  = iparticle->Pz();
 421
 422                           if (ipa > -1) {
 423                               iparent = pParent[ipa];
 424                           } else {
 425                               iparent = -1;
 426                           }
 427
 428                           SetTrack(fTrackIt*trackIt[i], iparent, kf,
 429                                            pc, och, polar,
 430                                            0, kPDecay, nt, wgtch);
 431                           pParent[i] = nt;
 432                           KeepTrack(nt);
 433                       } // Selected
 434                   } // Particle loop
 435               }  // Decays by Lujet
 436               particles->Clear();
 437               if (pFlag)      delete[] pFlag;
 438               if (pParent)    delete[] pParent;
 439               if (pSelected)  delete[] pSelected;
 440               if (trackIt)    delete[] trackIt;
 441           } // kinematic selection
 442           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 443           {
 444             gAlice->
 445                 SetTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 446             ipa++;
 447           }
 448           break;
 449     } // while
 450   } // event loop
 451   SetHighWaterMark(nt);
 452 }
 453
 454 void AliGenParam::Draw()
 455 {
 456     //
 457     // Draw the pT and y Distributions
 458     //
 459      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 460      c0->Divide(2,1);
 461      c0->cd(1);
 462      fPtPara->Draw();
 463      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 464      c0->cd(2);
 465      fYPara->Draw();
 466      fYPara->GetHistogram()->SetXTitle("y");
 467 }
 468
 469 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 470 {
 471 // Assignment operator
 472     return *this;
 473 }
 474
 475
 476