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         fPtParaFunc(0),
  54         fYParaFunc(0),
  55         fIpParaFunc(0),
  56         fPtPara(0),
  57         fYPara(0),
  58         fParam(0),
  59         fdNdy0(0.),
  60         fYWgt(0.),
  61         fPtWgt(0.),
  62         fBias(0.),
  63         fTrials(0),
  64         fDeltaPt(0.01),
  65         fDecayer(0)
  66 {
  67 // Default constructor
  68 }
  69 //____________________________________________________________
  70 AliGenParam::AliGenParam(Int_t npart, AliGenLib * Library,  Int_t param, char* tname)
  71     :AliGenMC(npart),
  72      fPtParaFunc(Library->GetPt(param, tname)),
  73      fYParaFunc (Library->GetY (param, tname)),
  74      fIpParaFunc(Library->GetIp(param, tname)),
  75      fPtPara(0),
  76      fYPara(0),
  77      fParam(param),
  78      fdNdy0(0.),
  79      fYWgt(0.),
  80      fPtWgt(0.),
  81      fBias(0.),
  82      fTrials(0),
  83      fDeltaPt(0.01),
  84      fDecayer(0)
  85 {
  86 // Constructor using number of particles parameterisation id and library
  87     fName = "Param";
  88     fTitle= "Particle Generator using pT and y parameterisation";
  89     fAnalog = kAnalog;
  90     SetForceDecay();
  91 }
  92 //____________________________________________________________
  93 AliGenParam::AliGenParam(Int_t npart, Int_t param, const char* tname, const char* name):
  94     AliGenMC(npart),
  95     fPtParaFunc(0),
  96     fYParaFunc (0),
  97     fIpParaFunc(0),
  98     fPtPara(0),
  99     fYPara(0),
 100     fParam(param),
 101     fdNdy0(0.),
 102     fYWgt(0.),
 103     fPtWgt(0.),
 104     fBias(0.),
 105     fTrials(0),
 106     fDeltaPt(0.01),
 107     fDecayer(0)
 108 {
 109 // Constructor using parameterisation id and number of particles
 110 //
 111     fName = name;
 112     fTitle= "Particle Generator using pT and y parameterisation";
 113
 114     AliGenLib* pLibrary = new AliGenMUONlib();
 115     fPtParaFunc = pLibrary->GetPt(param, tname);
 116     fYParaFunc  = pLibrary->GetY (param, tname);
 117     fIpParaFunc = pLibrary->GetIp(param, tname);
 118
 119     fAnalog = kAnalog;
 120     fChildSelect.Set(5);
 121     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 122     SetForceDecay();
 123     SetCutOnChild();
 124     SetChildMomentumRange();
 125     SetChildPtRange();
 126     SetChildPhiRange();
 127     SetChildThetaRange();
 128 }
 129 //____________________________________________________________
 130
 131 AliGenParam::AliGenParam(Int_t npart, Int_t param,
 132                          Double_t (*PtPara) (Double_t*, Double_t*),
 133                          Double_t (*YPara ) (Double_t* ,Double_t*),
 134                          Int_t    (*IpPara) (TRandom *))
 135     :AliGenMC(npart),
 136
 137      fPtParaFunc(PtPara),
 138      fYParaFunc(YPara),
 139      fIpParaFunc(IpPara),
 140      fPtPara(0),
 141      fYPara(0),
 142      fParam(param),
 143      fdNdy0(0.),
 144      fYWgt(0.),
 145      fPtWgt(0.),
 146      fBias(0.),
 147      fTrials(0),
 148      fDeltaPt(0.01),
 149      fDecayer(0)
 150 {
 151 // Constructor
 152 // Gines Martinez 1/10/99
 153     fName = "Param";
 154     fTitle= "Particle Generator using pT and y parameterisation";
 155
 156     fAnalog = kAnalog;
 157     fChildSelect.Set(5);
 158     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 159     SetForceDecay();
 160     SetCutOnChild();
 161     SetChildMomentumRange();
 162     SetChildPtRange();
 163     SetChildPhiRange();
 164     SetChildThetaRange();
 165 }
 166
 167 //____________________________________________________________
 168 AliGenParam::~AliGenParam()
 169 {
 170 // Destructor
 171     delete  fPtPara;
 172     delete  fYPara;
 173 }
 174
 175 //____________________________________________________________
 176 void AliGenParam::Init()
 177 {
 178 // Initialisation
 179
 180     if (gMC) fDecayer = gMC->GetDecayer();
 181   //Begin_Html
 182   /*
 183     <img src="picts/AliGenParam.gif">
 184   */
 185   //End_Html
 186     char name[256];
 187     sprintf(name, "pt-parameterisation for %s", GetName());
 188
 189     if (fPtPara) fPtPara->Delete();
 190     fPtPara = new TF1(name, fPtParaFunc, fPtMin, fPtMax,0);
 191     gROOT->GetListOfFunctions()->Remove(fPtPara);
 192 //  Set representation precision to 10 MeV
 193     Int_t npx= Int_t((fPtMax - fPtMin) / fDeltaPt);
 194
 195     fPtPara->SetNpx(npx);
 196
 197     sprintf(name, "y-parameterisation  for %s", GetName());
 198     if (fYPara) fYPara->Delete();
 199     fYPara  = new TF1(name, fYParaFunc, fYMin, fYMax, 0);
 200     gROOT->GetListOfFunctions()->Remove(fYPara);
 201
 202
 203     sprintf(name, "pt-for-%s", GetName());
 204     TF1 ptPara(name ,fPtParaFunc, 0, 15, 0);
 205     sprintf(name, "y-for-%s", GetName());
 206     TF1 yPara(name, fYParaFunc, -6, 6, 0);
 207
 208 //
 209 // dN/dy| y=0
 210     Double_t y1=0;
 211     Double_t y2=0;
 212
 213     fdNdy0=fYParaFunc(&y1,&y2);
 214 //
 215 // Integral over generation region
 216     Float_t intYS  = yPara.Integral(fYMin, fYMax,(Double_t*) 0x0,1.e-6);
 217     Float_t intPt0 = ptPara.Integral(0,15,(Double_t *) 0x0,1.e-6);
 218     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax,(Double_t*) 0x0,1.e-6);
 219     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 220     if (fAnalog == kAnalog) {
 221         fYWgt  = intYS/fdNdy0;
 222         fPtWgt = intPtS/intPt0;
 223         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 224     } else {
 225         fYWgt = intYS/fdNdy0;
 226         fPtWgt = (fPtMax-fPtMin)/intPt0;
 227         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 228     }
 229 //
 230 // particle decay related initialization
 231     fDecayer->SetForceDecay(fForceDecay);
 232     fDecayer->Init();
 233
 234 //
 235     AliGenMC::Init();
 236 }
 237
 238 //____________________________________________________________
 239 void AliGenParam::Generate()
 240 {
 241 //
 242 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 243 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 244 // antineutrons in the the desired theta, phi and momentum windows;
 245 // Gaussian smearing on the vertex is done if selected.
 246 // The decay of heavy mesons is done using lujet,
 247 //    and the childern particle are tracked by GEANT
 248 // However, light mesons are directly tracked by GEANT
 249 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 250 //
 251 //
 252 //  Reinitialize decayer
 253   fDecayer->SetForceDecay(fForceDecay);
 254   fDecayer->Init();
 255
 256 //
 257   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 258   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 259   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 260   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 261   Float_t p[3], pc[3],
 262           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 263   Double_t ty, xmt;
 264   Int_t nt, i, j;
 265   Float_t  wgtp, wgtch;
 266   Double_t dummy;
 267   static TClonesArray *particles;
 268   //
 269   if(!particles) particles = new TClonesArray("TParticle",1000);
 270
 271   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 272   //
 273   Float_t random[6];
 274
 275 // Calculating vertex position per event
 276   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 277   if(fVertexSmear==kPerEvent) {
 278       Vertex();
 279       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 280   }
 281
 282   Int_t ipa=0;
 283
 284 // Generating fNpart particles
 285   while (ipa<fNpart) {
 286       while(1) {
 287 //
 288 // particle type
 289           Int_t iPart = fIpParaFunc(fRandom);
 290           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 291           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 292           Float_t am = particle->Mass();
 293
 294           Rndm(random,2);
 295 //
 296 // phi
 297           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 298 //
 299 // y
 300           ty = TMath::TanH(fYPara->GetRandom());
 301 //
 302 // pT
 303           if (fAnalog == kAnalog) {
 304               pt=fPtPara->GetRandom();
 305               wgtp=fParentWeight;
 306               wgtch=fChildWeight;
 307           } else {
 308               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 309               Double_t ptd=pt;
 310               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 311               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 312           }
 313           xmt=sqrt(pt*pt+am*am);
 314           if (TMath::Abs(ty)==1.) {
 315               ty=0.;
 316               Fatal("AliGenParam",
 317                     "Division by 0: Please check you rapidity range !");
 318           }
 319
 320           pl=xmt*ty/sqrt(1.-ty*ty);
 321           theta=TMath::ATan2(pt,pl);
 322 // Cut on theta
 323           if(theta<fThetaMin || theta>fThetaMax) continue;
 324           ptot=TMath::Sqrt(pt*pt+pl*pl);
 325 // Cut on momentum
 326           if(ptot<fPMin || ptot>fPMax) continue;
 327 //
 328           p[0]=pt*TMath::Cos(phi);
 329           p[1]=pt*TMath::Sin(phi);
 330           p[2]=pl;
 331           if(fVertexSmear==kPerTrack) {
 332               Rndm(random,6);
 333               for (j=0;j<3;j++) {
 334                   origin0[j]=
 335                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 336                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 337               }
 338           }
 339
 340 // Looking at fForceDecay :
 341 // if fForceDecay != none Primary particle decays using
 342 // AliPythia and children are tracked by GEANT
 343 //
 344 // if fForceDecay == none Primary particle is tracked by GEANT
 345 // (In the latest, make sure that GEANT actually does all the decays you want)
 346 //
 347
 348           if (fForceDecay != kNoDecay) {
 349 // Using lujet to decay particle
 350               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 351               TLorentzVector pmom(p[0], p[1], p[2], energy);
 352               fDecayer->Decay(iPart,&pmom);
 353 //
 354 // select decay particles
 355               Int_t np=fDecayer->ImportParticles(particles);
 356
 357               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 358               if (fGeometryAcceptance)
 359                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 360               Int_t ncsel=0;
 361               Int_t* pFlag      = new Int_t[np];
 362               Int_t* pParent    = new Int_t[np];
 363               Int_t* pSelected  = new Int_t[np];
 364               Int_t* trackIt    = new Int_t[np];
 365
 366               for (i=0; i<np; i++) {
 367                   pFlag[i]     =  0;
 368                   pSelected[i] =  0;
 369                   pParent[i]   = -1;
 370               }
 371
 372               if (np >1) {
 373                   TParticle* iparticle =  (TParticle *) particles->At(0);
 374                   Int_t ipF, ipL;
 375                   for (i = 1; i<np ; i++) {
 376                       trackIt[i] = 1;
 377                       iparticle = (TParticle *) particles->At(i);
 378                       Int_t kf = iparticle->GetPdgCode();
 379                       Int_t ks = iparticle->GetStatusCode();
 380 // flagged particle
 381
 382                       if (pFlag[i] == 1) {
 383                           ipF = iparticle->GetFirstDaughter();
 384                           ipL = iparticle->GetLastDaughter();
 385                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 386                           continue;
 387                       }
 388
 389 // flag decay products of particles with long life-time (c tau > .3 mum)
 390
 391                       if (ks != 1) {
 392 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 393
 394                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 395 //                        Double_t mass     = particle->Mass();
 396 //                        Double_t width    = particle->Width();
 397                           if (lifeTime > (Double_t) fMaxLifeTime) {
 398                               ipF = iparticle->GetFirstDaughter();
 399                               ipL = iparticle->GetLastDaughter();
 400                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 401                           } else{
 402                               trackIt[i]     = 0;
 403                               pSelected[i]   = 1;
 404                           }
 405                       } // ks==1 ?
 406 //
 407 // children
 408
 409                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 410                       {
 411                           if (fCutOnChild) {
 412                               pc[0]=iparticle->Px();
 413                               pc[1]=iparticle->Py();
 414                               pc[2]=iparticle->Pz();
 415                               Bool_t  childok = KinematicSelection(iparticle, 1);
 416                               if(childok) {
 417                                   pSelected[i]  = 1;
 418                                   ncsel++;
 419                               } else {
 420                                   ncsel=-1;
 421                                   break;
 422                               } // child kine cuts
 423                           } else {
 424                               pSelected[i]  = 1;
 425                               ncsel++;
 426                           } // if child selection
 427                       } // select muon
 428                   } // decay particle loop
 429               } // if decay products
 430
 431               Int_t iparent;
 432               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 433                   ipa++;
 434 //
 435 // Parent
 436                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 437                   pParent[0] = nt;
 438                   KeepTrack(nt);
 439 //
 440 // Decay Products
 441 //
 442                   for (i = 1; i < np; i++) {
 443                       if (pSelected[i]) {
 444                           TParticle* iparticle = (TParticle *) particles->At(i);
 445                           Int_t kf  = iparticle->GetPdgCode();
 446                           Int_t ipa = iparticle->GetFirstMother()-1;
 447
 448                           och[0] = origin0[0]+iparticle->Vx()/10;
 449                           och[1] = origin0[1]+iparticle->Vy()/10;
 450                           och[2] = origin0[2]+iparticle->Vz()/10;
 451                           pc[0]  = iparticle->Px();
 452                           pc[1]  = iparticle->Py();
 453                           pc[2]  = iparticle->Pz();
 454
 455                           if (ipa > -1) {
 456                               iparent = pParent[ipa];
 457                           } else {
 458                               iparent = -1;
 459                           }
 460
 461                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 462                                            pc, och, polar,
 463                                            0, kPDecay, nt, wgtch);
 464                           pParent[i] = nt;
 465                           KeepTrack(nt);
 466                       } // Selected
 467                   } // Particle loop
 468               }  // Decays by Lujet
 469               particles->Clear();
 470               if (pFlag)      delete[] pFlag;
 471               if (pParent)    delete[] pParent;
 472               if (pSelected)  delete[] pSelected;
 473               if (trackIt)    delete[] trackIt;
 474           } // kinematic selection
 475           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 476           {
 477             gAlice->GetMCApp()->
 478                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 479             ipa++;
 480           }
 481           break;
 482     } // while
 483   } // event loop
 484   SetHighWaterMark(nt);
 485 }
 486 //____________________________________________________________________________________
 487 Float_t AliGenParam::GetRelativeArea(Float_t ptMin, Float_t ptMax, Float_t yMin, Float_t yMax, Float_t phiMin, Float_t phiMax)
 488 {
 489 //
 490 // Normalisation for selected kinematic region
 491 //
 492   Float_t ratio =
 493     fPtPara->Integral(ptMin,ptMax,(Double_t *)0,1.e-6) / fPtPara->Integral( fPtPara->GetXmin(), fPtPara->GetXmax(),(Double_t *)0,1.e-6) *
 494     fYPara->Integral(yMin,yMax,(Double_t *)0,1.e-6)/fYPara->Integral(fYPara->GetXmin(),fYPara->GetXmax(),(Double_t *)0,1.e-6)   *
 495     (phiMax-phiMin)/360.;
 496   return TMath::Abs(ratio);
 497 }
 498
 499 //____________________________________________________________________________________
 500
 501 void AliGenParam::Draw( const char * /*opt*/)
 502 {
 503     //
 504     // Draw the pT and y Distributions
 505     //
 506      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 507      c0->Divide(2,1);
 508      c0->cd(1);
 509      fPtPara->Draw();
 510      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 511      c0->cd(2);
 512      fYPara->Draw();
 513      fYPara->GetHistogram()->SetXTitle("y");
 514 }
 515
 516
 517
 518