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     char name[256];
 170     sprintf(name, "pt-parameterisation for %s", GetName());
 171
 172     fPtPara = new TF1(name, fPtParaFunc, fPtMin, fPtMax,0);
 173 //  Set representation precision to 10 MeV
 174     Int_t npx= Int_t((fPtMax - fPtMin) / fDeltaPt);
 175
 176     fPtPara->SetNpx(npx);
 177
 178     sprintf(name, "y-parameterisation  for %s", GetName());
 179     fYPara  = new TF1(name, fYParaFunc, fYMin, fYMax, 0);
 180
 181     sprintf(name, "pt-for-%s", GetName());
 182     TF1 ptPara(name ,fPtParaFunc, 0, 15, 0);
 183     sprintf(name, "y-for-%s", GetName());
 184     TF1 yPara(name, fYParaFunc, -6, 6, 0);
 185
 186 //
 187 // dN/dy| y=0
 188     Double_t y1=0;
 189     Double_t y2=0;
 190
 191     fdNdy0=fYParaFunc(&y1,&y2);
 192 //
 193 // Integral over generation region
 194     Float_t intYS  = yPara.Integral(fYMin, fYMax);
 195     Float_t intPt0 = ptPara.Integral(0,15);
 196     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax);
 197     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 198     if (fAnalog == kAnalog) {
 199         fYWgt  = intYS/fdNdy0;
 200         fPtWgt = intPtS/intPt0;
 201         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 202     } else {
 203         fYWgt = intYS/fdNdy0;
 204         fPtWgt = (fPtMax-fPtMin)/intPt0;
 205         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 206     }
 207 //
 208 // particle decay related initialization
 209     fDecayer->SetForceDecay(fForceDecay);
 210     fDecayer->Init();
 211
 212 //
 213     AliGenMC::Init();
 214 }
 215
 216 //____________________________________________________________
 217 void AliGenParam::Generate()
 218 {
 219 //
 220 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 221 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 222 // antineutrons in the the desired theta, phi and momentum windows;
 223 // Gaussian smearing on the vertex is done if selected.
 224 // The decay of heavy mesons is done using lujet,
 225 //    and the childern particle are tracked by GEANT
 226 // However, light mesons are directly tracked by GEANT
 227 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 228 //
 229 //
 230 //  Reinitialize decayer
 231     fDecayer->Init();
 232 //
 233   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 234   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 235   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 236   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 237   Float_t p[3], pc[3],
 238           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 239   Double_t ty, xmt;
 240   Int_t nt, i, j;
 241   Float_t  wgtp, wgtch;
 242   Double_t dummy;
 243   static TClonesArray *particles;
 244   //
 245   if(!particles) particles = new TClonesArray("TParticle",1000);
 246
 247   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 248   //
 249   Float_t random[6];
 250
 251 // Calculating vertex position per event
 252   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 253   if(fVertexSmear==kPerEvent) {
 254       Vertex();
 255       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 256   }
 257
 258   Int_t ipa=0;
 259
 260 // Generating fNpart particles
 261   while (ipa<fNpart) {
 262       while(1) {
 263 //
 264 // particle type
 265           Int_t iPart = fIpParaFunc(fRandom);
 266           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 267           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 268           Float_t am = particle->Mass();
 269
 270           Rndm(random,2);
 271 //
 272 // phi
 273           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 274 //
 275 // y
 276           ty = TMath::TanH(fYPara->GetRandom());
 277 //
 278 // pT
 279           if (fAnalog == kAnalog) {
 280               pt=fPtPara->GetRandom();
 281               wgtp=fParentWeight;
 282               wgtch=fChildWeight;
 283           } else {
 284               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 285               Double_t ptd=pt;
 286               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 287               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 288           }
 289           xmt=sqrt(pt*pt+am*am);
 290           if (TMath::Abs(ty)==1.) {
 291               ty=0.;
 292               Fatal("AliGenParam",
 293                     "Division by 0: Please check you rapidity range !");
 294           }
 295
 296           pl=xmt*ty/sqrt(1.-ty*ty);
 297           theta=TMath::ATan2(pt,pl);
 298 // Cut on theta
 299           if(theta<fThetaMin || theta>fThetaMax) continue;
 300           ptot=TMath::Sqrt(pt*pt+pl*pl);
 301 // Cut on momentum
 302           if(ptot<fPMin || ptot>fPMax) continue;
 303 //
 304           p[0]=pt*TMath::Cos(phi);
 305           p[1]=pt*TMath::Sin(phi);
 306           p[2]=pl;
 307           if(fVertexSmear==kPerTrack) {
 308               Rndm(random,6);
 309               for (j=0;j<3;j++) {
 310                   origin0[j]=
 311                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 312                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 313               }
 314           }
 315
 316 // Looking at fForceDecay :
 317 // if fForceDecay != none Primary particle decays using
 318 // AliPythia and children are tracked by GEANT
 319 //
 320 // if fForceDecay == none Primary particle is tracked by GEANT
 321 // (In the latest, make sure that GEANT actually does all the decays you want)
 322 //
 323
 324           if (fForceDecay != kNoDecay) {
 325 // Using lujet to decay particle
 326               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 327               TLorentzVector pmom(p[0], p[1], p[2], energy);
 328               fDecayer->Decay(iPart,&pmom);
 329 //
 330 // select decay particles
 331               Int_t np=fDecayer->ImportParticles(particles);
 332
 333               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 334               if (fGeometryAcceptance)
 335                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 336               Int_t ncsel=0;
 337               Int_t* pFlag      = new Int_t[np];
 338               Int_t* pParent    = new Int_t[np];
 339               Int_t* pSelected  = new Int_t[np];
 340               Int_t* trackIt    = new Int_t[np];
 341
 342               for (i=0; i<np; i++) {
 343                   pFlag[i]     =  0;
 344                   pSelected[i] =  0;
 345                   pParent[i]   = -1;
 346               }
 347
 348               if (np >1) {
 349                   TParticle* iparticle =  (TParticle *) particles->At(0);
 350                   Int_t ipF, ipL;
 351                   for (i = 1; i<np ; i++) {
 352                       trackIt[i] = 1;
 353                       iparticle = (TParticle *) particles->At(i);
 354                       Int_t kf = iparticle->GetPdgCode();
 355                       Int_t ks = iparticle->GetStatusCode();
 356 // flagged particle
 357
 358                       if (pFlag[i] == 1) {
 359                           ipF = iparticle->GetFirstDaughter();
 360                           ipL = iparticle->GetLastDaughter();
 361                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 362                           continue;
 363                       }
 364
 365 // flag decay products of particles with long life-time (c tau > .3 mum)
 366
 367                       if (ks != 1) {
 368 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 369
 370                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 371 //                        Double_t mass     = particle->Mass();
 372 //                        Double_t width    = particle->Width();
 373                           if (lifeTime > (Double_t) fMaxLifeTime) {
 374                               ipF = iparticle->GetFirstDaughter();
 375                               ipL = iparticle->GetLastDaughter();
 376                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 377                           } else{
 378                               trackIt[i]     = 0;
 379                               pSelected[i]   = 1;
 380                           }
 381                       } // ks==1 ?
 382 //
 383 // children
 384
 385                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 386                       {
 387                           if (fCutOnChild) {
 388                               pc[0]=iparticle->Px();
 389                               pc[1]=iparticle->Py();
 390                               pc[2]=iparticle->Pz();
 391                               Bool_t  childok = KinematicSelection(iparticle, 1);
 392                               if(childok) {
 393                                   pSelected[i]  = 1;
 394                                   ncsel++;
 395                               } else {
 396                                   ncsel=-1;
 397                                   break;
 398                               } // child kine cuts
 399                           } else {
 400                               pSelected[i]  = 1;
 401                               ncsel++;
 402                           } // if child selection
 403                       } // select muon
 404                   } // decay particle loop
 405               } // if decay products
 406
 407               Int_t iparent;
 408               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 409                   ipa++;
 410 //
 411 // Parent
 412                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 413                   pParent[0] = nt;
 414                   KeepTrack(nt);
 415 //
 416 // Decay Products
 417 //
 418                   for (i = 1; i < np; i++) {
 419                       if (pSelected[i]) {
 420                           TParticle* iparticle = (TParticle *) particles->At(i);
 421                           Int_t kf  = iparticle->GetPdgCode();
 422                           Int_t ipa = iparticle->GetFirstMother()-1;
 423
 424                           och[0] = origin0[0]+iparticle->Vx()/10;
 425                           och[1] = origin0[1]+iparticle->Vy()/10;
 426                           och[2] = origin0[2]+iparticle->Vz()/10;
 427                           pc[0]  = iparticle->Px();
 428                           pc[1]  = iparticle->Py();
 429                           pc[2]  = iparticle->Pz();
 430
 431                           if (ipa > -1) {
 432                               iparent = pParent[ipa];
 433                           } else {
 434                               iparent = -1;
 435                           }
 436
 437                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 438                                            pc, och, polar,
 439                                            0, kPDecay, nt, wgtch);
 440                           pParent[i] = nt;
 441                           KeepTrack(nt);
 442                       } // Selected
 443                   } // Particle loop
 444               }  // Decays by Lujet
 445               particles->Clear();
 446               if (pFlag)      delete[] pFlag;
 447               if (pParent)    delete[] pParent;
 448               if (pSelected)  delete[] pSelected;
 449               if (trackIt)    delete[] trackIt;
 450           } // kinematic selection
 451           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 452           {
 453             gAlice->GetMCApp()->
 454                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 455             ipa++;
 456           }
 457           break;
 458     } // while
 459   } // event loop
 460   SetHighWaterMark(nt);
 461 }
 462
 463 void AliGenParam::Draw( const char * /*opt*/)
 464 {
 465     //
 466     // Draw the pT and y Distributions
 467     //
 468      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 469      c0->Divide(2,1);
 470      c0->cd(1);
 471      fPtPara->Draw();
 472      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 473      c0->cd(2);
 474      fYPara->Draw();
 475      fYPara->GetHistogram()->SetXTitle("y");
 476 }
 477
 478 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 479 {
 480 // Assignment operator
 481     rhs.Copy(*this);
 482     return *this;
 483 }
 484
 485
 486