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 <TCanvas.h>
  25 #include <TDatabasePDG.h>
  26 #include <TF1.h>
  27 #include <TH1F.h>
  28 #include <TLorentzVector.h>
  29 #include <TMath.h>
  30 #include <TParticle.h>
  31 #include <TParticlePDG.h>
  32 #include <TROOT.h>
  33 #include <TVirtualMC.h>
  34
  35 #include "AliDecayer.h"
  36 #include "AliGenMUONlib.h"
  37 #include "AliGenParam.h"
  38 #include "AliMC.h"
  39 #include "AliRun.h"
  40
  41 ClassImp(AliGenParam)
  42
  43 //------------------------------------------------------------
  44
  45   //Begin_Html
  46   /*
  47     <img src="picts/AliGenParam.gif">
  48   */
  49   //End_Html
  50
  51 //____________________________________________________________
  52 AliGenParam::AliGenParam()
  53 {
  54 // Deafault constructor
  55     fPtPara = 0;
  56     fYPara  = 0;
  57     fParam  = 0;
  58     fAnalog = kAnalog;
  59     SetDeltaPt();
  60     fDecayer = 0;
  61
  62
  63 }
  64 //____________________________________________________________
  65 AliGenParam::AliGenParam(Int_t npart, AliGenLib * Library,  Int_t param, char* tname):AliGenMC(npart)
  66 {
  67 // Constructor using number of particles parameterisation id and library
  68     fName = "Param";
  69     fTitle= "Particle Generator using pT and y parameterisation";
  70
  71     fPtParaFunc = Library->GetPt(param, tname);
  72     fYParaFunc  = Library->GetY (param, tname);
  73     fIpParaFunc = Library->GetIp(param, tname);
  74
  75     fPtPara = 0;
  76     fYPara  = 0;
  77     fParam  = param;
  78     fAnalog = kAnalog;
  79     SetForceDecay();
  80     SetDeltaPt();
  81 }
  82 //____________________________________________________________
  83 AliGenParam::AliGenParam(Int_t npart, Int_t param, const char* tname, const char* name):AliGenMC(npart)
  84 {
  85 // Constructor using parameterisation id and number of particles
  86 //
  87   fName = name;
  88   fTitle= "Particle Generator using pT and y parameterisation";
  89
  90     AliGenLib* pLibrary = new AliGenMUONlib();
  91
  92     fPtParaFunc = pLibrary->GetPt(param, tname);
  93     fYParaFunc  = pLibrary->GetY (param, tname);
  94     fIpParaFunc = pLibrary->GetIp(param, tname);
  95
  96     fPtPara = 0;
  97     fYPara  = 0;
  98     fParam  = param;
  99     fAnalog = kAnalog;
 100     fChildSelect.Set(5);
 101     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 102     SetForceDecay();
 103     SetCutOnChild();
 104     SetChildMomentumRange();
 105     SetChildPtRange();
 106     SetChildPhiRange();
 107     SetChildThetaRange();
 108     SetDeltaPt();
 109 }
 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     if (fPtPara) fPtPara->Delete();
 173     fPtPara = new TF1(name, fPtParaFunc, fPtMin, fPtMax,0);
 174     gROOT->GetListOfFunctions()->Remove(fPtPara);
 175 //  Set representation precision to 10 MeV
 176     Int_t npx= Int_t((fPtMax - fPtMin) / fDeltaPt);
 177
 178     fPtPara->SetNpx(npx);
 179
 180     sprintf(name, "y-parameterisation  for %s", GetName());
 181     if (fYPara) fYPara->Delete();
 182     fYPara  = new TF1(name, fYParaFunc, fYMin, fYMax, 0);
 183     gROOT->GetListOfFunctions()->Remove(fYPara);
 184
 185
 186     sprintf(name, "pt-for-%s", GetName());
 187     TF1 ptPara(name ,fPtParaFunc, 0, 15, 0);
 188     sprintf(name, "y-for-%s", GetName());
 189     TF1 yPara(name, fYParaFunc, -6, 6, 0);
 190
 191 //
 192 // dN/dy| y=0
 193     Double_t y1=0;
 194     Double_t y2=0;
 195
 196     fdNdy0=fYParaFunc(&y1,&y2);
 197 //
 198 // Integral over generation region
 199     Float_t intYS  = yPara.Integral(fYMin, fYMax);
 200     Float_t intPt0 = ptPara.Integral(0,15);
 201     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax);
 202     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 203     if (fAnalog == kAnalog) {
 204         fYWgt  = intYS/fdNdy0;
 205         fPtWgt = intPtS/intPt0;
 206         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 207     } else {
 208         fYWgt = intYS/fdNdy0;
 209         fPtWgt = (fPtMax-fPtMin)/intPt0;
 210         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 211     }
 212 //
 213 // particle decay related initialization
 214     fDecayer->SetForceDecay(fForceDecay);
 215     fDecayer->Init();
 216
 217 //
 218     AliGenMC::Init();
 219 }
 220
 221 //____________________________________________________________
 222 void AliGenParam::Generate()
 223 {
 224 //
 225 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 226 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 227 // antineutrons in the the desired theta, phi and momentum windows;
 228 // Gaussian smearing on the vertex is done if selected.
 229 // The decay of heavy mesons is done using lujet,
 230 //    and the childern particle are tracked by GEANT
 231 // However, light mesons are directly tracked by GEANT
 232 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 233 //
 234 //
 235 //  Reinitialize decayer
 236   fDecayer->SetForceDecay(fForceDecay);
 237   fDecayer->Init();
 238
 239 //
 240   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 241   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 242   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 243   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 244   Float_t p[3], pc[3],
 245           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 246   Double_t ty, xmt;
 247   Int_t nt, i, j;
 248   Float_t  wgtp, wgtch;
 249   Double_t dummy;
 250   static TClonesArray *particles;
 251   //
 252   if(!particles) particles = new TClonesArray("TParticle",1000);
 253
 254   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 255   //
 256   Float_t random[6];
 257
 258 // Calculating vertex position per event
 259   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 260   if(fVertexSmear==kPerEvent) {
 261       Vertex();
 262       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 263   }
 264
 265   Int_t ipa=0;
 266
 267 // Generating fNpart particles
 268   while (ipa<fNpart) {
 269       while(1) {
 270 //
 271 // particle type
 272           Int_t iPart = fIpParaFunc(fRandom);
 273           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 274           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 275           Float_t am = particle->Mass();
 276
 277           Rndm(random,2);
 278 //
 279 // phi
 280           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 281 //
 282 // y
 283           ty = TMath::TanH(fYPara->GetRandom());
 284 //
 285 // pT
 286           if (fAnalog == kAnalog) {
 287               pt=fPtPara->GetRandom();
 288               wgtp=fParentWeight;
 289               wgtch=fChildWeight;
 290           } else {
 291               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 292               Double_t ptd=pt;
 293               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 294               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 295           }
 296           xmt=sqrt(pt*pt+am*am);
 297           if (TMath::Abs(ty)==1.) {
 298               ty=0.;
 299               Fatal("AliGenParam",
 300                     "Division by 0: Please check you rapidity range !");
 301           }
 302
 303           pl=xmt*ty/sqrt(1.-ty*ty);
 304           theta=TMath::ATan2(pt,pl);
 305 // Cut on theta
 306           if(theta<fThetaMin || theta>fThetaMax) continue;
 307           ptot=TMath::Sqrt(pt*pt+pl*pl);
 308 // Cut on momentum
 309           if(ptot<fPMin || ptot>fPMax) continue;
 310 //
 311           p[0]=pt*TMath::Cos(phi);
 312           p[1]=pt*TMath::Sin(phi);
 313           p[2]=pl;
 314           if(fVertexSmear==kPerTrack) {
 315               Rndm(random,6);
 316               for (j=0;j<3;j++) {
 317                   origin0[j]=
 318                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 319                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 320               }
 321           }
 322
 323 // Looking at fForceDecay :
 324 // if fForceDecay != none Primary particle decays using
 325 // AliPythia and children are tracked by GEANT
 326 //
 327 // if fForceDecay == none Primary particle is tracked by GEANT
 328 // (In the latest, make sure that GEANT actually does all the decays you want)
 329 //
 330
 331           if (fForceDecay != kNoDecay) {
 332 // Using lujet to decay particle
 333               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 334               TLorentzVector pmom(p[0], p[1], p[2], energy);
 335               fDecayer->Decay(iPart,&pmom);
 336 //
 337 // select decay particles
 338               Int_t np=fDecayer->ImportParticles(particles);
 339
 340               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 341               if (fGeometryAcceptance)
 342                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 343               Int_t ncsel=0;
 344               Int_t* pFlag      = new Int_t[np];
 345               Int_t* pParent    = new Int_t[np];
 346               Int_t* pSelected  = new Int_t[np];
 347               Int_t* trackIt    = new Int_t[np];
 348
 349               for (i=0; i<np; i++) {
 350                   pFlag[i]     =  0;
 351                   pSelected[i] =  0;
 352                   pParent[i]   = -1;
 353               }
 354
 355               if (np >1) {
 356                   TParticle* iparticle =  (TParticle *) particles->At(0);
 357                   Int_t ipF, ipL;
 358                   for (i = 1; i<np ; i++) {
 359                       trackIt[i] = 1;
 360                       iparticle = (TParticle *) particles->At(i);
 361                       Int_t kf = iparticle->GetPdgCode();
 362                       Int_t ks = iparticle->GetStatusCode();
 363 // flagged particle
 364
 365                       if (pFlag[i] == 1) {
 366                           ipF = iparticle->GetFirstDaughter();
 367                           ipL = iparticle->GetLastDaughter();
 368                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 369                           continue;
 370                       }
 371
 372 // flag decay products of particles with long life-time (c tau > .3 mum)
 373
 374                       if (ks != 1) {
 375 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 376
 377                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 378 //                        Double_t mass     = particle->Mass();
 379 //                        Double_t width    = particle->Width();
 380                           if (lifeTime > (Double_t) fMaxLifeTime) {
 381                               ipF = iparticle->GetFirstDaughter();
 382                               ipL = iparticle->GetLastDaughter();
 383                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 384                           } else{
 385                               trackIt[i]     = 0;
 386                               pSelected[i]   = 1;
 387                           }
 388                       } // ks==1 ?
 389 //
 390 // children
 391
 392                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 393                       {
 394                           if (fCutOnChild) {
 395                               pc[0]=iparticle->Px();
 396                               pc[1]=iparticle->Py();
 397                               pc[2]=iparticle->Pz();
 398                               Bool_t  childok = KinematicSelection(iparticle, 1);
 399                               if(childok) {
 400                                   pSelected[i]  = 1;
 401                                   ncsel++;
 402                               } else {
 403                                   ncsel=-1;
 404                                   break;
 405                               } // child kine cuts
 406                           } else {
 407                               pSelected[i]  = 1;
 408                               ncsel++;
 409                           } // if child selection
 410                       } // select muon
 411                   } // decay particle loop
 412               } // if decay products
 413
 414               Int_t iparent;
 415               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 416                   ipa++;
 417 //
 418 // Parent
 419                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 420                   pParent[0] = nt;
 421                   KeepTrack(nt);
 422 //
 423 // Decay Products
 424 //
 425                   for (i = 1; i < np; i++) {
 426                       if (pSelected[i]) {
 427                           TParticle* iparticle = (TParticle *) particles->At(i);
 428                           Int_t kf  = iparticle->GetPdgCode();
 429                           Int_t ipa = iparticle->GetFirstMother()-1;
 430
 431                           och[0] = origin0[0]+iparticle->Vx()/10;
 432                           och[1] = origin0[1]+iparticle->Vy()/10;
 433                           och[2] = origin0[2]+iparticle->Vz()/10;
 434                           pc[0]  = iparticle->Px();
 435                           pc[1]  = iparticle->Py();
 436                           pc[2]  = iparticle->Pz();
 437
 438                           if (ipa > -1) {
 439                               iparent = pParent[ipa];
 440                           } else {
 441                               iparent = -1;
 442                           }
 443
 444                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 445                                            pc, och, polar,
 446                                            0, kPDecay, nt, wgtch);
 447                           pParent[i] = nt;
 448                           KeepTrack(nt);
 449                       } // Selected
 450                   } // Particle loop
 451               }  // Decays by Lujet
 452               particles->Clear();
 453               if (pFlag)      delete[] pFlag;
 454               if (pParent)    delete[] pParent;
 455               if (pSelected)  delete[] pSelected;
 456               if (trackIt)    delete[] trackIt;
 457           } // kinematic selection
 458           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 459           {
 460             gAlice->GetMCApp()->
 461                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 462             ipa++;
 463           }
 464           break;
 465     } // while
 466   } // event loop
 467   SetHighWaterMark(nt);
 468 }
 469 //____________________________________________________________________________________
 470 Float_t AliGenParam::GetRelativeArea(Float_t ptMin, Float_t ptMax, Float_t yMin, Float_t yMax, Float_t phiMin, Float_t phiMax)
 471 {
 472 //
 473 // Normalisation for selected kinematic region
 474 //
 475   Float_t ratio =
 476     fPtPara->Integral(ptMin,ptMax) / fPtPara->Integral( fPtPara->GetXmin(), fPtPara->GetXmax()) *
 477     fYPara->Integral(yMin,yMax)/fYPara->Integral(fYPara->GetXmin(),fYPara->GetXmax())   *
 478     (phiMax-phiMin)/360.;
 479   return TMath::Abs(ratio);
 480 }
 481
 482 //____________________________________________________________________________________
 483
 484 void AliGenParam::Draw( const char * /*opt*/)
 485 {
 486     //
 487     // Draw the pT and y Distributions
 488     //
 489      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 490      c0->Divide(2,1);
 491      c0->cd(1);
 492      fPtPara->Draw();
 493      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 494      c0->cd(2);
 495      fYPara->Draw();
 496      fYPara->GetHistogram()->SetXTitle("y");
 497 }
 498
 499 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 500 {
 501 // Assignment operator
 502     rhs.Copy(*this);
 503     return *this;
 504 }
 505
 506
 507