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 <TMath.h>
  38 #include "AliMC.h"
  39
  40 ClassImp(AliGenParam)
  41
  42 //------------------------------------------------------------
  43
  44   //Begin_Html
  45   /*
  46     <img src="picts/AliGenParam.gif">
  47   */
  48   //End_Html
  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 AliGenParam::AliGenParam(Int_t npart, Int_t param, const char* tname, const char* name):AliGenMC(npart)
  83 {
  84 // Constructor using parameterisation id and number of particles
  85 //
  86   fName = name;
  87   fTitle= "Particle Generator using pT and y parameterisation";
  88
  89     AliGenLib* pLibrary = new AliGenMUONlib();
  90
  91     fPtParaFunc = pLibrary->GetPt(param, tname);
  92     fYParaFunc  = pLibrary->GetY (param, tname);
  93     fIpParaFunc = pLibrary->GetIp(param, tname);
  94
  95     fPtPara = 0;
  96     fYPara  = 0;
  97     fParam  = param;
  98     fAnalog = kAnalog;
  99     fChildSelect.Set(5);
 100     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 101     SetForceDecay();
 102     SetCutOnChild();
 103     SetChildMomentumRange();
 104     SetChildPtRange();
 105     SetChildPhiRange();
 106     SetChildThetaRange();
 107     SetDeltaPt();
 108 }
 109 //____________________________________________________________
 110
 111 AliGenParam::AliGenParam(Int_t npart, Int_t param,
 112                          Double_t (*PtPara) (Double_t*, Double_t*),
 113                          Double_t (*YPara ) (Double_t* ,Double_t*),
 114                          Int_t    (*IpPara) (TRandom *))
 115     :AliGenMC(npart)
 116 {
 117 // Constructor
 118 // Gines Martinez 1/10/99
 119     fName = "Param";
 120     fTitle= "Particle Generator using pT and y parameterisation";
 121
 122     fPtParaFunc = PtPara;
 123     fYParaFunc  = YPara;
 124     fIpParaFunc = IpPara;
 125 //
 126     fPtPara = 0;
 127     fYPara  = 0;
 128     fParam  = param;
 129     fAnalog = kAnalog;
 130     fChildSelect.Set(5);
 131     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
 132     SetForceDecay();
 133     SetCutOnChild();
 134     SetChildMomentumRange();
 135     SetChildPtRange();
 136     SetChildPhiRange();
 137     SetChildThetaRange();
 138     SetDeltaPt();
 139 }
 140
 141
 142 AliGenParam::AliGenParam(const AliGenParam & Param)
 143     :AliGenMC(Param)
 144 {
 145 // Copy constructor
 146     Param.Copy(*this);
 147 }
 148
 149 //____________________________________________________________
 150 AliGenParam::~AliGenParam()
 151 {
 152 // Destructor
 153     delete  fPtPara;
 154     delete  fYPara;
 155 }
 156
 157 //____________________________________________________________
 158 void AliGenParam::Init()
 159 {
 160 // Initialisation
 161
 162     if (gMC) fDecayer = gMC->GetDecayer();
 163   //Begin_Html
 164   /*
 165     <img src="picts/AliGenParam.gif">
 166   */
 167   //End_Html
 168     char name[256];
 169     sprintf(name, "pt-parameterisation for %s", GetName());
 170
 171     if (fPtPara) fPtPara->Delete();
 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     if (fYPara) fYPara->Delete();
 180     fYPara  = new TF1(name, fYParaFunc, fYMin, fYMax, 0);
 181
 182     sprintf(name, "pt-for-%s", GetName());
 183     TF1 ptPara(name ,fPtParaFunc, 0, 15, 0);
 184     sprintf(name, "y-for-%s", GetName());
 185     TF1 yPara(name, fYParaFunc, -6, 6, 0);
 186
 187 //
 188 // dN/dy| y=0
 189     Double_t y1=0;
 190     Double_t y2=0;
 191
 192     fdNdy0=fYParaFunc(&y1,&y2);
 193 //
 194 // Integral over generation region
 195     Float_t intYS  = yPara.Integral(fYMin, fYMax);
 196     Float_t intPt0 = ptPara.Integral(0,15);
 197     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax);
 198     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
 199     if (fAnalog == kAnalog) {
 200         fYWgt  = intYS/fdNdy0;
 201         fPtWgt = intPtS/intPt0;
 202         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 203     } else {
 204         fYWgt = intYS/fdNdy0;
 205         fPtWgt = (fPtMax-fPtMin)/intPt0;
 206         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
 207     }
 208 //
 209 // particle decay related initialization
 210     fDecayer->SetForceDecay(fForceDecay);
 211     fDecayer->Init();
 212
 213 //
 214     AliGenMC::Init();
 215 }
 216
 217 //____________________________________________________________
 218 void AliGenParam::Generate()
 219 {
 220 //
 221 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
 222 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and
 223 // antineutrons in the the desired theta, phi and momentum windows;
 224 // Gaussian smearing on the vertex is done if selected.
 225 // The decay of heavy mesons is done using lujet,
 226 //    and the childern particle are tracked by GEANT
 227 // However, light mesons are directly tracked by GEANT
 228 // setting fForceDecay = nodecay (SetForceDecay(nodecay))
 229 //
 230 //
 231 //  Reinitialize decayer
 232   fDecayer->SetForceDecay(fForceDecay);
 233   fDecayer->Init();
 234
 235 //
 236   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
 237   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
 238   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
 239   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
 240   Float_t p[3], pc[3],
 241           och[3];             // Momentum, polarisation and origin of the children particles from lujet
 242   Double_t ty, xmt;
 243   Int_t nt, i, j;
 244   Float_t  wgtp, wgtch;
 245   Double_t dummy;
 246   static TClonesArray *particles;
 247   //
 248   if(!particles) particles = new TClonesArray("TParticle",1000);
 249
 250   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
 251   //
 252   Float_t random[6];
 253
 254 // Calculating vertex position per event
 255   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
 256   if(fVertexSmear==kPerEvent) {
 257       Vertex();
 258       for (j=0;j<3;j++) origin0[j]=fVertex[j];
 259   }
 260
 261   Int_t ipa=0;
 262
 263 // Generating fNpart particles
 264   while (ipa<fNpart) {
 265       while(1) {
 266 //
 267 // particle type
 268           Int_t iPart = fIpParaFunc(fRandom);
 269           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;
 270           TParticlePDG *particle = pDataBase->GetParticle(iPart);
 271           Float_t am = particle->Mass();
 272
 273           Rndm(random,2);
 274 //
 275 // phi
 276           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
 277 //
 278 // y
 279           ty = TMath::TanH(fYPara->GetRandom());
 280 //
 281 // pT
 282           if (fAnalog == kAnalog) {
 283               pt=fPtPara->GetRandom();
 284               wgtp=fParentWeight;
 285               wgtch=fChildWeight;
 286           } else {
 287               pt=fPtMin+random[1]*(fPtMax-fPtMin);
 288               Double_t ptd=pt;
 289               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
 290               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
 291           }
 292           xmt=sqrt(pt*pt+am*am);
 293           if (TMath::Abs(ty)==1.) {
 294               ty=0.;
 295               Fatal("AliGenParam",
 296                     "Division by 0: Please check you rapidity range !");
 297           }
 298
 299           pl=xmt*ty/sqrt(1.-ty*ty);
 300           theta=TMath::ATan2(pt,pl);
 301 // Cut on theta
 302           if(theta<fThetaMin || theta>fThetaMax) continue;
 303           ptot=TMath::Sqrt(pt*pt+pl*pl);
 304 // Cut on momentum
 305           if(ptot<fPMin || ptot>fPMax) continue;
 306 //
 307           p[0]=pt*TMath::Cos(phi);
 308           p[1]=pt*TMath::Sin(phi);
 309           p[2]=pl;
 310           if(fVertexSmear==kPerTrack) {
 311               Rndm(random,6);
 312               for (j=0;j<3;j++) {
 313                   origin0[j]=
 314                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
 315                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
 316               }
 317           }
 318
 319 // Looking at fForceDecay :
 320 // if fForceDecay != none Primary particle decays using
 321 // AliPythia and children are tracked by GEANT
 322 //
 323 // if fForceDecay == none Primary particle is tracked by GEANT
 324 // (In the latest, make sure that GEANT actually does all the decays you want)
 325 //
 326
 327           if (fForceDecay != kNoDecay) {
 328 // Using lujet to decay particle
 329               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
 330               TLorentzVector pmom(p[0], p[1], p[2], energy);
 331               fDecayer->Decay(iPart,&pmom);
 332 //
 333 // select decay particles
 334               Int_t np=fDecayer->ImportParticles(particles);
 335
 336               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
 337               if (fGeometryAcceptance)
 338                 if (!CheckAcceptanceGeometry(np,particles)) continue;
 339               Int_t ncsel=0;
 340               Int_t* pFlag      = new Int_t[np];
 341               Int_t* pParent    = new Int_t[np];
 342               Int_t* pSelected  = new Int_t[np];
 343               Int_t* trackIt    = new Int_t[np];
 344
 345               for (i=0; i<np; i++) {
 346                   pFlag[i]     =  0;
 347                   pSelected[i] =  0;
 348                   pParent[i]   = -1;
 349               }
 350
 351               if (np >1) {
 352                   TParticle* iparticle =  (TParticle *) particles->At(0);
 353                   Int_t ipF, ipL;
 354                   for (i = 1; i<np ; i++) {
 355                       trackIt[i] = 1;
 356                       iparticle = (TParticle *) particles->At(i);
 357                       Int_t kf = iparticle->GetPdgCode();
 358                       Int_t ks = iparticle->GetStatusCode();
 359 // flagged particle
 360
 361                       if (pFlag[i] == 1) {
 362                           ipF = iparticle->GetFirstDaughter();
 363                           ipL = iparticle->GetLastDaughter();
 364                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 365                           continue;
 366                       }
 367
 368 // flag decay products of particles with long life-time (c tau > .3 mum)
 369
 370                       if (ks != 1) {
 371 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
 372
 373                           Double_t lifeTime = fDecayer->GetLifetime(kf);
 374 //                        Double_t mass     = particle->Mass();
 375 //                        Double_t width    = particle->Width();
 376                           if (lifeTime > (Double_t) fMaxLifeTime) {
 377                               ipF = iparticle->GetFirstDaughter();
 378                               ipL = iparticle->GetLastDaughter();
 379                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
 380                           } else{
 381                               trackIt[i]     = 0;
 382                               pSelected[i]   = 1;
 383                           }
 384                       } // ks==1 ?
 385 //
 386 // children
 387
 388                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
 389                       {
 390                           if (fCutOnChild) {
 391                               pc[0]=iparticle->Px();
 392                               pc[1]=iparticle->Py();
 393                               pc[2]=iparticle->Pz();
 394                               Bool_t  childok = KinematicSelection(iparticle, 1);
 395                               if(childok) {
 396                                   pSelected[i]  = 1;
 397                                   ncsel++;
 398                               } else {
 399                                   ncsel=-1;
 400                                   break;
 401                               } // child kine cuts
 402                           } else {
 403                               pSelected[i]  = 1;
 404                               ncsel++;
 405                           } // if child selection
 406                       } // select muon
 407                   } // decay particle loop
 408               } // if decay products
 409
 410               Int_t iparent;
 411               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
 412                   ipa++;
 413 //
 414 // Parent
 415                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
 416                   pParent[0] = nt;
 417                   KeepTrack(nt);
 418 //
 419 // Decay Products
 420 //
 421                   for (i = 1; i < np; i++) {
 422                       if (pSelected[i]) {
 423                           TParticle* iparticle = (TParticle *) particles->At(i);
 424                           Int_t kf  = iparticle->GetPdgCode();
 425                           Int_t ipa = iparticle->GetFirstMother()-1;
 426
 427                           och[0] = origin0[0]+iparticle->Vx()/10;
 428                           och[1] = origin0[1]+iparticle->Vy()/10;
 429                           och[2] = origin0[2]+iparticle->Vz()/10;
 430                           pc[0]  = iparticle->Px();
 431                           pc[1]  = iparticle->Py();
 432                           pc[2]  = iparticle->Pz();
 433
 434                           if (ipa > -1) {
 435                               iparent = pParent[ipa];
 436                           } else {
 437                               iparent = -1;
 438                           }
 439
 440                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
 441                                            pc, och, polar,
 442                                            0, kPDecay, nt, wgtch);
 443                           pParent[i] = nt;
 444                           KeepTrack(nt);
 445                       } // Selected
 446                   } // Particle loop
 447               }  // Decays by Lujet
 448               particles->Clear();
 449               if (pFlag)      delete[] pFlag;
 450               if (pParent)    delete[] pParent;
 451               if (pSelected)  delete[] pSelected;
 452               if (trackIt)    delete[] trackIt;
 453           } // kinematic selection
 454           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
 455           {
 456             gAlice->GetMCApp()->
 457                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
 458             ipa++;
 459           }
 460           break;
 461     } // while
 462   } // event loop
 463   SetHighWaterMark(nt);
 464 }
 465 //____________________________________________________________________________________
 466 Float_t AliGenParam::GetRelativeArea(Float_t ptMin, Float_t ptMax, Float_t yMin, Float_t yMax, Float_t phiMin, Float_t phiMax)
 467 {
 468 //
 469 // Normalisation for selected kinematic region
 470 //
 471   Float_t ratio =
 472     fPtPara->Integral(ptMin,ptMax) / fPtPara->Integral( fPtPara->GetXmin(), fPtPara->GetXmax()) *
 473     fYPara->Integral(yMin,yMax)/fYPara->Integral(fYPara->GetXmin(),fYPara->GetXmax())   *
 474     (phiMax-phiMin)/360.;
 475   return TMath::Abs(ratio);
 476 }
 477
 478 //____________________________________________________________________________________
 479
 480 void AliGenParam::Draw( const char * /*opt*/)
 481 {
 482     //
 483     // Draw the pT and y Distributions
 484     //
 485      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
 486      c0->Divide(2,1);
 487      c0->cd(1);
 488      fPtPara->Draw();
 489      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");
 490      c0->cd(2);
 491      fYPara->Draw();
 492      fYPara->GetHistogram()->SetXTitle("y");
 493 }
 494
 495 AliGenParam& AliGenParam::operator=(const  AliGenParam& rhs)
 496 {
 497 // Assignment operator
 498     rhs.Copy(*this);
 499     return *this;
 500 }
 501
 502
 503