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(const AliGenParam & Param)
 169     :AliGenMC(Param),
 170      fPtParaFunc(0),
 171      fYParaFunc(0),
 172      fIpParaFunc(0),
 173      fPtPara(0),
 174      fYPara(0),
 175      fParam(0),
 176      fdNdy0(0.),
 177      fYWgt(0.),
 178      fPtWgt(0.),
 179      fBias(0.),
 180      fTrials(0),
 181      fDeltaPt(0.01),
 182      fDecayer(0)
 183 {
 184 // Copy constructor
 185     Param.Copy(*this);
 186 }
 187
 188 //____________________________________________________________
 189 AliGenParam::~AliGenParam()
 190 {
 191 // Destructor
 192     delete  fPtPara;
 193     delete  fYPara;
 194 }
 195
 196 //____________________________________________________________
 197 void AliGenParam::Init()
 198 {
 199 // Initialisation
 200
 201     if (gMC) fDecayer = gMC->GetDecayer();
 202   //Begin_Html
 203   /*
 204     <img src="picts/AliGenParam.gif">
 205   */
 206   //End_Html
 207     char name[256];
 208     sprintf(name, "pt-parameterisation for %s", GetName());
 209
 210     if (fPtPara) fPtPara->Delete();
 211     fPtPara = new TF1(name, fPtParaFunc, fPtMin, fPtMax,0);
 212     gROOT->GetListOfFunctions()->Remove(fPtPara);
 213 //  Set representation precision to 10 MeV
 214     Int_t npx= Int_t((fPtMax - fPtMin) / fDeltaPt);
 215
 216     fPtPara->SetNpx(npx);
 217
 218     sprintf(name, "y-parameterisation  for %s", GetName());
 219     if (fYPara) fYPara->Delete();
 220     fYPara  = new TF1(name, fYParaFunc, fYMin, fYMax, 0);
 221     gROOT->GetListOfFunctions()->Remove(fYPara);
 222
 223
 224     sprintf(name, "pt-for-%s", GetName());
 225     TF1 ptPara(name ,fPtParaFunc, 0, 15, 0);
 226     sprintf(name, "y-for-%s", GetName());
 227     TF1 yPara(name, fYParaFunc, -6, 6, 0);
 228
 229 //
 230 // dN/dy| y=0
 231     Double_t y1=0;
 232     Double_t y2=0;
 233
 234     fdNdy0=fYParaFunc(&y1,&y2);
 235 //
 236 // Integral over generation region
 237     Float_t intYS  = yPara.Integral(fYMin, fYMax,(Double_t*) 0x0,1.e-6);
 238     Float_t intPt0 = ptPara.Integral(0,15,(Double_t *) 0x0,1.e-6);
 239     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax,(Double_t*) 0x0,1.e-6);
 240     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 241     if (fAnalog == kAnalog) {
 242         fYWgt  = intYS/fdNdy0;
 243         fPtWgt = intPtS/intPt0;
 244         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 245     } else {
 246         fYWgt = intYS/fdNdy0;
 247         fPtWgt = (fPtMax-fPtMin)/intPt0;
 248         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 249     }
 250 //
 251 // particle decay related initialization
 252     fDecayer->SetForceDecay(fForceDecay);
 253     fDecayer->Init();
 254
 255 //
 256     AliGenMC::Init();
 257 }
 258
 259 //____________________________________________________________
 260 void AliGenParam::Generate()
 261 {
 262 //
 263 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 264 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 265 // antineutrons in the the desired theta, phi and momentum windows;
 266 // Gaussian smearing on the vertex is done if selected.
 267 // The decay of heavy mesons is done using lujet,
 268 //    and the childern particle are tracked by GEANT
 269 // However, light mesons are directly tracked by GEANT
 270 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 271 //
 272 //
 273 //  Reinitialize decayer
 274   fDecayer->SetForceDecay(fForceDecay);
 275   fDecayer->Init();
 276
 277 //
 278   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 279   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 280   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 281   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 282   Float_t p[3], pc[3],
 283           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 284   Double_t ty, xmt;
 285   Int_t nt, i, j;
 286   Float_t  wgtp, wgtch;
 287   Double_t dummy;
 288   static TClonesArray *particles;
 289   //
 290   if(!particles) particles = new TClonesArray("TParticle",1000);
 291
 292   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 293   //
 294   Float_t random[6];
 295
 296 // Calculating vertex position per event
 297   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 298   if(fVertexSmear==kPerEvent) {
 299       Vertex();
 300       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 301   }
 302
 303   Int_t ipa=0;
 304
 305 // Generating fNpart particles
 306   while (ipa<fNpart) {
 307       while(1) {
 308 //
 309 // particle type
 310           Int_t iPart = fIpParaFunc(fRandom);
 311           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 312           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 313           Float_t am = particle->Mass();
 314
 315           Rndm(random,2);
 316 //
 317 // phi
 318           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 319 //
 320 // y
 321           ty = TMath::TanH(fYPara->GetRandom());
 322 //
 323 // pT
 324           if (fAnalog == kAnalog) {
 325               pt=fPtPara->GetRandom();
 326               wgtp=fParentWeight;
 327               wgtch=fChildWeight;
 328           } else {
 329               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 330               Double_t ptd=pt;
 331               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 332               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 333           }
 334           xmt=sqrt(pt*pt+am*am);
 335           if (TMath::Abs(ty)==1.) {
 336               ty=0.;
 337               Fatal("AliGenParam",
 338                     "Division by 0: Please check you rapidity range !");
 339           }
 340
 341           pl=xmt*ty/sqrt(1.-ty*ty);
 342           theta=TMath::ATan2(pt,pl);
 343 // Cut on theta
 344           if(theta<fThetaMin || theta>fThetaMax) continue;
 345           ptot=TMath::Sqrt(pt*pt+pl*pl);
 346 // Cut on momentum
 347           if(ptot<fPMin || ptot>fPMax) continue;
 348 //
 349           p[0]=pt*TMath::Cos(phi);
 350           p[1]=pt*TMath::Sin(phi);
 351           p[2]=pl;
 352           if(fVertexSmear==kPerTrack) {
 353               Rndm(random,6);
 354               for (j=0;j<3;j++) {
 355                   origin0[j]=
 356                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 357                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 358               }
 359           }
 360
 361 // Looking at fForceDecay :
 362 // if fForceDecay != none Primary particle decays using
 363 // AliPythia and children are tracked by GEANT
 364 //
 365 // if fForceDecay == none Primary particle is tracked by GEANT
 366 // (In the latest, make sure that GEANT actually does all the decays you want)
 367 //
 368
 369           if (fForceDecay != kNoDecay) {
 370 // Using lujet to decay particle
 371               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 372               TLorentzVector pmom(p[0], p[1], p[2], energy);
 373               fDecayer->Decay(iPart,&pmom);
 374 //
 375 // select decay particles
 376               Int_t np=fDecayer->ImportParticles(particles);
 377
 378               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 379               if (fGeometryAcceptance)
 380                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 381               Int_t ncsel=0;
 382               Int_t* pFlag      = new Int_t[np];
 383               Int_t* pParent    = new Int_t[np];
 384               Int_t* pSelected  = new Int_t[np];
 385               Int_t* trackIt    = new Int_t[np];
 386
 387               for (i=0; i<np; i++) {
 388                   pFlag[i]     =  0;
 389                   pSelected[i] =  0;
 390                   pParent[i]   = -1;
 391               }
 392
 393               if (np >1) {
 394                   TParticle* iparticle =  (TParticle *) particles->At(0);
 395                   Int_t ipF, ipL;
 396                   for (i = 1; i<np ; i++) {
 397                       trackIt[i] = 1;
 398                       iparticle = (TParticle *) particles->At(i);
 399                       Int_t kf = iparticle->GetPdgCode();
 400                       Int_t ks = iparticle->GetStatusCode();
 401 // flagged particle
 402
 403                       if (pFlag[i] == 1) {
 404                           ipF = iparticle->GetFirstDaughter();
 405                           ipL = iparticle->GetLastDaughter();
 406                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 407                           continue;
 408                       }
 409
 410 // flag decay products of particles with long life-time (c tau > .3 mum)
 411
 412                       if (ks != 1) {
 413 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 414
 415                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 416 //                        Double_t mass     = particle->Mass();
 417 //                        Double_t width    = particle->Width();
 418                           if (lifeTime > (Double_t) fMaxLifeTime) {
 419                               ipF = iparticle->GetFirstDaughter();
 420                               ipL = iparticle->GetLastDaughter();
 421                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 422                           } else{
 423                               trackIt[i]     = 0;
 424                               pSelected[i]   = 1;
 425                           }
 426                       } // ks==1 ?
 427 //
 428 // children
 429
 430                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 431                       {
 432                           if (fCutOnChild) {
 433                               pc[0]=iparticle->Px();
 434                               pc[1]=iparticle->Py();
 435                               pc[2]=iparticle->Pz();
 436                               Bool_t  childok = KinematicSelection(iparticle, 1);
 437                               if(childok) {
 438                                   pSelected[i]  = 1;
 439                                   ncsel++;
 440                               } else {
 441                                   ncsel=-1;
 442                                   break;
 443                               } // child kine cuts
 444                           } else {
 445                               pSelected[i]  = 1;
 446                               ncsel++;
 447                           } // if child selection
 448                       } // select muon
 449                   } // decay particle loop
 450               } // if decay products
 451
 452               Int_t iparent;
 453               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 454                   ipa++;
 455 //
 456 // Parent
 457                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 458                   pParent[0] = nt;
 459                   KeepTrack(nt);
 460 //
 461 // Decay Products
 462 //
 463                   for (i = 1; i < np; i++) {
 464                       if (pSelected[i]) {
 465                           TParticle* iparticle = (TParticle *) particles->At(i);
 466                           Int_t kf  = iparticle->GetPdgCode();
 467                           Int_t ipa = iparticle->GetFirstMother()-1;
 468
 469                           och[0] = origin0[0]+iparticle->Vx()/10;
 470                           och[1] = origin0[1]+iparticle->Vy()/10;
 471                           och[2] = origin0[2]+iparticle->Vz()/10;
 472                           pc[0]  = iparticle->Px();
 473                           pc[1]  = iparticle->Py();
 474                           pc[2]  = iparticle->Pz();
 475
 476                           if (ipa > -1) {
 477                               iparent = pParent[ipa];
 478                           } else {
 479                               iparent = -1;
 480                           }
 481
 482                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 483                                            pc, och, polar,
 484                                            0, kPDecay, nt, wgtch);
 485                           pParent[i] = nt;
 486                           KeepTrack(nt);
 487                       } // Selected
 488                   } // Particle loop
 489               }  // Decays by Lujet
 490               particles->Clear();
 491               if (pFlag)      delete[] pFlag;
 492               if (pParent)    delete[] pParent;
 493               if (pSelected)  delete[] pSelected;
 494               if (trackIt)    delete[] trackIt;
 495           } // kinematic selection
 496           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 497           {
 498             gAlice->GetMCApp()->
 499                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 500             ipa++;
 501           }
 502           break;
 503     } // while
 504   } // event loop
 505   SetHighWaterMark(nt);
 506 }
 507 //____________________________________________________________________________________
 508 Float_t AliGenParam::GetRelativeArea(Float_t ptMin, Float_t ptMax, Float_t yMin, Float_t yMax, Float_t phiMin, Float_t phiMax)
 509 {
 510 //
 511 // Normalisation for selected kinematic region
 512 //
 513   Float_t ratio =
 514     fPtPara->Integral(ptMin,ptMax,(Double_t *)0,1.e-6) / fPtPara->Integral( fPtPara->GetXmin(), fPtPara->GetXmax(),(Double_t *)0,1.e-6) *
 515     fYPara->Integral(yMin,yMax,(Double_t *)0,1.e-6)/fYPara->Integral(fYPara->GetXmin(),fYPara->GetXmax(),(Double_t *)0,1.e-6)   *
 516     (phiMax-phiMin)/360.;
 517   return TMath::Abs(ratio);
 518 }
 519
 520 //____________________________________________________________________________________
 521
 522 void AliGenParam::Draw( const char * /*opt*/)
 523 {
 524     //
 525     // Draw the pT and y Distributions
 526     //
 527      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 528      c0->Divide(2,1);
 529      c0->cd(1);
 530      fPtPara->Draw();
 531      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 532      c0->cd(2);
 533      fYPara->Draw();
 534      fYPara->GetHistogram()->SetXTitle("y");
 535 }
 536
 537 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 538 {
 539 // Assignment operator
 540     rhs.Copy(*this);
 541     return *this;
 542 }
 543
 544
 545