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 #include <TVirtualMC.h>
  33
  34 #include <TF1.h>
  35 #include <TCanvas.h>
  36 #include <TH1.h>
  37 #include "AliMC.h"
  38
  39 ClassImp(AliGenParam)
  40
  41 //------------------------------------------------------------
  42
  43   //Begin_Html
  44   /*
  45     <img src="picts/AliGenParam.gif">
  46   */
  47   //End_Html
  48
  49 //____________________________________________________________
  50 //____________________________________________________________
  51 AliGenParam::AliGenParam()
  52 {
  53 // Deafault constructor
  54     fPtPara = 0;
  55     fYPara  = 0;
  56     fParam  = 0;
  57     fAnalog = kAnalog;
  58     SetDeltaPt();
  59     fDecayer = 0;
  60
  61
  62 }
  63
  64 AliGenParam::AliGenParam(Int_t npart, AliGenLib * Library,  Int_t param, char* tname):AliGenMC(npart)
  65 {
  66 // Constructor using number of particles parameterisation id and library
  67     fName = "Param";
  68     fTitle= "Particle Generator using pT and y parameterisation";
  69
  70     fPtParaFunc = Library->GetPt(param, tname);
  71     fYParaFunc  = Library->GetY (param, tname);
  72     fIpParaFunc = Library->GetIp(param, tname);
  73
  74     fPtPara = 0;
  75     fYPara  = 0;
  76     fParam  = param;
  77     fAnalog = kAnalog;
  78     SetForceDecay();
  79     SetDeltaPt();
  80 }
  81
  82 //____________________________________________________________
  83
  84 AliGenParam::AliGenParam(Int_t npart, Int_t param, char* tname):AliGenMC(npart)
  85 {
  86 // Constructor using parameterisation id and number of particles
  87 //
  88     fName = "Param";
  89     fTitle= "Particle Generator using pT and y parameterisation";
  90
  91     AliGenLib* pLibrary = new AliGenMUONlib();
  92
  93     fPtParaFunc = pLibrary->GetPt(param, tname);
  94     fYParaFunc  = pLibrary->GetY (param, tname);
  95     fIpParaFunc = pLibrary->GetIp(param, tname);
  96
  97     fPtPara = 0;
  98     fYPara  = 0;
  99     fParam  = param;
 100     fAnalog = kAnalog;
 101     fChildSelect.Set(5);
 102     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 103     SetForceDecay();
 104     SetCutOnChild();
 105     SetChildMomentumRange();
 106     SetChildPtRange();
 107     SetChildPhiRange();
 108     SetChildThetaRange();
 109     SetDeltaPt();
 110 }
 111
 112 AliGenParam::AliGenParam(Int_t npart, Int_t param,
 113                          Double_t (*PtPara) (Double_t*, Double_t*),
 114                          Double_t (*YPara ) (Double_t* ,Double_t*),
 115                          Int_t    (*IpPara) (TRandom *))
 116     :AliGenMC(npart)
 117 {
 118 // Constructor
 119 // Gines Martinez 1/10/99
 120     fName = "Param";
 121     fTitle= "Particle Generator using pT and y parameterisation";
 122
 123     fPtParaFunc = PtPara;
 124     fYParaFunc  = YPara;
 125     fIpParaFunc = IpPara;
 126 //
 127     fPtPara = 0;
 128     fYPara  = 0;
 129     fParam  = param;
 130     fAnalog = kAnalog;
 131     fChildSelect.Set(5);
 132     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 133     SetForceDecay();
 134     SetCutOnChild();
 135     SetChildMomentumRange();
 136     SetChildPtRange();
 137     SetChildPhiRange();
 138     SetChildThetaRange();
 139     SetDeltaPt();
 140 }
 141
 142
 143 AliGenParam::AliGenParam(const AliGenParam & Param)
 144     :AliGenMC(Param)
 145 {
 146 // Copy constructor
 147     Param.Copy(*this);
 148 }
 149
 150 //____________________________________________________________
 151 AliGenParam::~AliGenParam()
 152 {
 153 // Destructor
 154     delete  fPtPara;
 155     delete  fYPara;
 156 }
 157
 158 //____________________________________________________________
 159 void AliGenParam::Init()
 160 {
 161 // Initialisation
 162
 163     if (gMC) fDecayer = gMC->GetDecayer();
 164   //Begin_Html
 165   /*
 166     <img src="picts/AliGenParam.gif">
 167   */
 168   //End_Html
 169
 170     fPtPara = new TF1("Pt-Parametrization",fPtParaFunc,fPtMin,fPtMax,0);
 171 //  Set representation precision to 10 MeV
 172     Int_t npx= Int_t((fPtMax-fPtMin)/fDeltaPt);
 173
 174     fPtPara->SetNpx(npx);
 175
 176     fYPara  = new TF1("Y-Parametrization",fYParaFunc,fYMin,fYMax,0);
 177     TF1 ptPara("Pt-Parametrization(0,15)",fPtParaFunc,0,15,0);
 178     TF1 yPara("Y-Parametrization(-6,6)",fYParaFunc,-6,6,0);
 179
 180 //
 181 // dN/dy| y=0
 182     Double_t y1=0;
 183     Double_t y2=0;
 184
 185     fdNdy0=fYParaFunc(&y1,&y2);
 186 //
 187 // Integral over generation region
 188     Float_t intYS  = yPara.Integral(fYMin, fYMax);
 189     Float_t intPt0 = ptPara.Integral(0,15);
 190     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax);
 191     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 192     if (fAnalog == kAnalog) {
 193         fYWgt  = intYS/fdNdy0;
 194         fPtWgt = intPtS/intPt0;
 195         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 196     } else {
 197         fYWgt = intYS/fdNdy0;
 198         fPtWgt = (fPtMax-fPtMin)/intPt0;
 199         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 200     }
 201 //
 202 // particle decay related initialization
 203     fDecayer->SetForceDecay(fForceDecay);
 204     fDecayer->Init();
 205
 206 //
 207     AliGenMC::Init();
 208 }
 209
 210 //____________________________________________________________
 211 void AliGenParam::Generate()
 212 {
 213 //
 214 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 215 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 216 // antineutrons in the the desired theta, phi and momentum windows;
 217 // Gaussian smearing on the vertex is done if selected.
 218 // The decay of heavy mesons is done using lujet,
 219 //    and the childern particle are tracked by GEANT
 220 // However, light mesons are directly tracked by GEANT
 221 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 222 //
 223 //
 224 //  Reinitialize decayer
 225     fDecayer->Init();
 226 //
 227   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 228   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 229   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 230   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 231   Float_t p[3], pc[3],
 232           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 233   Double_t ty, xmt;
 234   Int_t nt, i, j;
 235   Float_t  wgtp, wgtch;
 236   Double_t dummy;
 237   static TClonesArray *particles;
 238   //
 239   if(!particles) particles = new TClonesArray("TParticle",1000);
 240
 241   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 242   //
 243   Float_t random[6];
 244
 245 // Calculating vertex position per event
 246   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 247   if(fVertexSmear==kPerEvent) {
 248       Vertex();
 249       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 250   }
 251
 252   Int_t ipa=0;
 253
 254 // Generating fNpart particles
 255   while (ipa<fNpart) {
 256       while(1) {
 257 //
 258 // particle type
 259           Int_t iPart = fIpParaFunc(fRandom);
 260           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 261           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 262           Float_t am = particle->Mass();
 263
 264           Rndm(random,2);
 265 //
 266 // phi
 267           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 268 //
 269 // y
 270           ty = TMath::TanH(fYPara->GetRandom());
 271 //
 272 // pT
 273           if (fAnalog == kAnalog) {
 274               pt=fPtPara->GetRandom();
 275               wgtp=fParentWeight;
 276               wgtch=fChildWeight;
 277           } else {
 278               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 279               Double_t ptd=pt;
 280               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 281               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 282           }
 283           xmt=sqrt(pt*pt+am*am);
 284           if (TMath::Abs(ty)==1.) {
 285               ty=0.;
 286               Fatal("AliGenParam",
 287                     "Division by 0: Please check you rapidity range !");
 288           }
 289
 290           pl=xmt*ty/sqrt(1.-ty*ty);
 291           theta=TMath::ATan2(pt,pl);
 292 // Cut on theta
 293           if(theta<fThetaMin || theta>fThetaMax) continue;
 294           ptot=TMath::Sqrt(pt*pt+pl*pl);
 295 // Cut on momentum
 296           if(ptot<fPMin || ptot>fPMax) continue;
 297 //
 298           p[0]=pt*TMath::Cos(phi);
 299           p[1]=pt*TMath::Sin(phi);
 300           p[2]=pl;
 301           if(fVertexSmear==kPerTrack) {
 302               Rndm(random,6);
 303               for (j=0;j<3;j++) {
 304                   origin0[j]=
 305                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 306                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 307               }
 308           }
 309
 310 // Looking at fForceDecay :
 311 // if fForceDecay != none Primary particle decays using
 312 // AliPythia and children are tracked by GEANT
 313 //
 314 // if fForceDecay == none Primary particle is tracked by GEANT
 315 // (In the latest, make sure that GEANT actually does all the decays you want)
 316 //
 317
 318           if (fForceDecay != kNoDecay) {
 319 // Using lujet to decay particle
 320               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 321               TLorentzVector pmom(p[0], p[1], p[2], energy);
 322               fDecayer->Decay(iPart,&pmom);
 323 //
 324 // select decay particles
 325               Int_t np=fDecayer->ImportParticles(particles);
 326
 327               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 328               if (fGeometryAcceptance)
 329                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 330               Int_t ncsel=0;
 331               Int_t* pFlag      = new Int_t[np];
 332               Int_t* pParent    = new Int_t[np];
 333               Int_t* pSelected  = new Int_t[np];
 334               Int_t* trackIt    = new Int_t[np];
 335
 336               for (i=0; i<np; i++) {
 337                   pFlag[i]     =  0;
 338                   pSelected[i] =  0;
 339                   pParent[i]   = -1;
 340               }
 341
 342               if (np >1) {
 343                   TParticle* iparticle =  (TParticle *) particles->At(0);
 344                   Int_t ipF, ipL;
 345                   for (i = 1; i<np ; i++) {
 346                       trackIt[i] = 1;
 347                       iparticle = (TParticle *) particles->At(i);
 348                       Int_t kf = iparticle->GetPdgCode();
 349                       Int_t ks = iparticle->GetStatusCode();
 350 // flagged particle
 351
 352                       if (pFlag[i] == 1) {
 353                           ipF = iparticle->GetFirstDaughter();
 354                           ipL = iparticle->GetLastDaughter();
 355                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 356                           continue;
 357                       }
 358
 359 // flag decay products of particles with long life-time (c tau > .3 mum)
 360
 361                       if (ks != 1) {
 362 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 363
 364                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 365 //                        Double_t mass     = particle->Mass();
 366 //                        Double_t width    = particle->Width();
 367                           if (lifeTime > (Double_t) fMaxLifeTime) {
 368                               ipF = iparticle->GetFirstDaughter();
 369                               ipL = iparticle->GetLastDaughter();
 370                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 371                           } else{
 372                               trackIt[i]     = 0;
 373                               pSelected[i]   = 1;
 374                           }
 375                       } // ks==1 ?
 376 //
 377 // children
 378
 379                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 380                       {
 381                           if (fCutOnChild) {
 382                               pc[0]=iparticle->Px();
 383                               pc[1]=iparticle->Py();
 384                               pc[2]=iparticle->Pz();
 385                               Bool_t  childok = KinematicSelection(iparticle, 1);
 386                               if(childok) {
 387                                   pSelected[i]  = 1;
 388                                   ncsel++;
 389                               } else {
 390                                   ncsel=-1;
 391                                   break;
 392                               } // child kine cuts
 393                           } else {
 394                               pSelected[i]  = 1;
 395                               ncsel++;
 396                           } // if child selection
 397                       } // select muon
 398                   } // decay particle loop
 399               } // if decay products
 400
 401               Int_t iparent;
 402               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 403                   ipa++;
 404 //
 405 // Parent
 406                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 407                   pParent[0] = nt;
 408                   KeepTrack(nt);
 409 //
 410 // Decay Products
 411 //
 412                   for (i = 1; i < np; i++) {
 413                       if (pSelected[i]) {
 414                           TParticle* iparticle = (TParticle *) particles->At(i);
 415                           Int_t kf  = iparticle->GetPdgCode();
 416                           Int_t ipa = iparticle->GetFirstMother()-1;
 417
 418                           och[0] = origin0[0]+iparticle->Vx()/10;
 419                           och[1] = origin0[1]+iparticle->Vy()/10;
 420                           och[2] = origin0[2]+iparticle->Vz()/10;
 421                           pc[0]  = iparticle->Px();
 422                           pc[1]  = iparticle->Py();
 423                           pc[2]  = iparticle->Pz();
 424
 425                           if (ipa > -1) {
 426                               iparent = pParent[ipa];
 427                           } else {
 428                               iparent = -1;
 429                           }
 430
 431                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 432                                            pc, och, polar,
 433                                            0, kPDecay, nt, wgtch);
 434                           pParent[i] = nt;
 435                           KeepTrack(nt);
 436                       } // Selected
 437                   } // Particle loop
 438               }  // Decays by Lujet
 439               particles->Clear();
 440               if (pFlag)      delete[] pFlag;
 441               if (pParent)    delete[] pParent;
 442               if (pSelected)  delete[] pSelected;
 443               if (trackIt)    delete[] trackIt;
 444           } // kinematic selection
 445           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 446           {
 447             gAlice->GetMCApp()->
 448                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 449             ipa++;
 450           }
 451           break;
 452     } // while
 453   } // event loop
 454   SetHighWaterMark(nt);
 455 }
 456
 457 void AliGenParam::Draw()
 458 {
 459     //
 460     // Draw the pT and y Distributions
 461     //
 462      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 463      c0->Divide(2,1);
 464      c0->cd(1);
 465      fPtPara->Draw();
 466      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 467      c0->cd(2);
 468      fYPara->Draw();
 469      fYPara->GetHistogram()->SetXTitle("y");
 470 }
 471
 472 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 473 {
 474 // Assignment operator
 475     rhs.Copy(*this);
 476     return *this;
 477 }
 478
 479
 480