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[u/mrichter/AliRoot.git] / 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   *
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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 <TClonesArray.h>
26 #include <TDatabasePDG.h>
27 #include <TF1.h>
28 #include <TH1F.h>
29 #include <TLorentzVector.h>
30 #include <TMath.h>
31 #include <TParticle.h>
32 #include <TParticlePDG.h>
33 #include <TROOT.h>
34 #include <TVirtualMC.h>
35
36 #include "AliDecayer.h"
37 #include "AliGenMUONlib.h"
38 #include "AliGenParam.h"
39 #include "AliMC.h"
40 #include "AliRun.h"
41
42 ClassImp(AliGenParam)
43
44 //------------------------------------------------------------
45
46   //Begin_Html
47   /*
48     <img src="picts/AliGenParam.gif">
49   */
50   //End_Html
51
52 //____________________________________________________________
53     AliGenParam::AliGenParam():
54         fPtParaFunc(0),
55         fYParaFunc(0),
56         fIpParaFunc(0),
57         fPtPara(0),
58         fYPara(0),
59         fParam(0),
60         fdNdy0(0.),
61         fYWgt(0.),
62         fPtWgt(0.),
63         fBias(0.),
64         fTrials(0),
65         fDeltaPt(0.01),
66         fDecayer(0)
67 {
68 // Default constructor
69 }
70 //____________________________________________________________
71 AliGenParam::AliGenParam(Int_t npart, AliGenLib * Library,  Int_t param, char* tname)
72     :AliGenMC(npart),
73      fPtParaFunc(Library->GetPt(param, tname)),
74      fYParaFunc (Library->GetY (param, tname)),
75      fIpParaFunc(Library->GetIp(param, tname)),
76      fPtPara(0),
77      fYPara(0),
78      fParam(param),
79      fdNdy0(0.),
80      fYWgt(0.),
81      fPtWgt(0.),
82      fBias(0.),
83      fTrials(0),
84      fDeltaPt(0.01),
85      fDecayer(0)
86 {
87 // Constructor using number of particles parameterisation id and library
88     fName = "Param";
89     fTitle= "Particle Generator using pT and y parameterisation";
90     fAnalog = kAnalog;
91     SetForceDecay();
92 }
93 //____________________________________________________________
94 AliGenParam::AliGenParam(Int_t npart, Int_t param, const char* tname, const char* name):
95     AliGenMC(npart),
96     fPtParaFunc(0),
97     fYParaFunc (0),
98     fIpParaFunc(0),
99     fPtPara(0),
100     fYPara(0),
101     fParam(param),
102     fdNdy0(0.),
103     fYWgt(0.),
104     fPtWgt(0.),
105     fBias(0.),
106     fTrials(0),
107     fDeltaPt(0.01),
108     fDecayer(0)
109 {
110 // Constructor using parameterisation id and number of particles
111 //
112     fName = name;
113     fTitle= "Particle Generator using pT and y parameterisation";
114       
115     AliGenLib* pLibrary = new AliGenMUONlib();
116     fPtParaFunc = pLibrary->GetPt(param, tname);
117     fYParaFunc  = pLibrary->GetY (param, tname);
118     fIpParaFunc = pLibrary->GetIp(param, tname);
119     
120     fAnalog = kAnalog;
121     fChildSelect.Set(5);
122     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
123     SetForceDecay();
124     SetCutOnChild();
125     SetChildMomentumRange();
126     SetChildPtRange();
127     SetChildPhiRange();
128     SetChildThetaRange(); 
129 }
130 //____________________________________________________________
131
132 AliGenParam::AliGenParam(Int_t npart, Int_t param,
133                          Double_t (*PtPara) (Double_t*, Double_t*),
134                          Double_t (*YPara ) (Double_t* ,Double_t*),
135                          Int_t    (*IpPara) (TRandom *))                 
136     :AliGenMC(npart),
137      
138      fPtParaFunc(PtPara),
139      fYParaFunc(YPara),
140      fIpParaFunc(IpPara),
141      fPtPara(0),
142      fYPara(0),
143      fParam(param),
144      fdNdy0(0.),
145      fYWgt(0.),
146      fPtWgt(0.),
147      fBias(0.),
148      fTrials(0),
149      fDeltaPt(0.01),
150      fDecayer(0)
151 {
152 // Constructor
153 // Gines Martinez 1/10/99 
154     fName = "Param";
155     fTitle= "Particle Generator using pT and y parameterisation";
156
157     fAnalog = kAnalog;
158     fChildSelect.Set(5);
159     for (Int_t i=0; i<5; i++) fChildSelect[i]=0;
160     SetForceDecay();
161     SetCutOnChild();
162     SetChildMomentumRange();
163     SetChildPtRange();
164     SetChildPhiRange();
165     SetChildThetaRange();  
166 }
167
168 //____________________________________________________________
169 AliGenParam::~AliGenParam()
170 {
171 // Destructor
172     delete  fPtPara;
173     delete  fYPara;
174 }
175
176 //____________________________________________________________
177 void AliGenParam::Init()
178 {
179 // Initialisation
180
181     if (gMC) fDecayer = gMC->GetDecayer();
182   //Begin_Html
183   /*
184     <img src="picts/AliGenParam.gif">
185   */
186   //End_Html
187     char name[256];
188     sprintf(name, "pt-parameterisation for %s", GetName());
189     
190     if (fPtPara) fPtPara->Delete();
191     fPtPara = new TF1(name, fPtParaFunc, fPtMin, fPtMax,0);
192     gROOT->GetListOfFunctions()->Remove(fPtPara);
193 //  Set representation precision to 10 MeV
194     Int_t npx= Int_t((fPtMax - fPtMin) / fDeltaPt);
195     
196     fPtPara->SetNpx(npx);
197
198     sprintf(name, "y-parameterisation  for %s", GetName());
199     if (fYPara) fYPara->Delete();
200     fYPara  = new TF1(name, fYParaFunc, fYMin, fYMax, 0);
201     gROOT->GetListOfFunctions()->Remove(fYPara);
202
203     
204     sprintf(name, "pt-for-%s", GetName());
205     TF1 ptPara(name ,fPtParaFunc, 0, 15, 0);
206     sprintf(name, "y-for-%s", GetName());
207     TF1 yPara(name, fYParaFunc, -6, 6, 0);
208
209 //
210 // dN/dy| y=0
211     Double_t y1=0;
212     Double_t y2=0;
213     
214     fdNdy0=fYParaFunc(&y1,&y2);
215 //
216 // Integral over generation region
217     Float_t intYS  = yPara.Integral(fYMin, fYMax,(Double_t*) 0x0,1.e-6);
218     Float_t intPt0 = ptPara.Integral(0,15,(Double_t *) 0x0,1.e-6);
219     Float_t intPtS = ptPara.Integral(fPtMin,fPtMax,(Double_t*) 0x0,1.e-6);
220     Float_t phiWgt=(fPhiMax-fPhiMin)/2./TMath::Pi();
221     if (fAnalog == kAnalog) {
222         fYWgt  = intYS/fdNdy0;
223         fPtWgt = intPtS/intPt0;
224         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
225     } else {
226         fYWgt = intYS/fdNdy0;
227         fPtWgt = (fPtMax-fPtMin)/intPt0;
228         fParentWeight = fYWgt*fPtWgt*phiWgt/fNpart;
229     }
230 //
231 // particle decay related initialization
232     fDecayer->SetForceDecay(fForceDecay);
233     fDecayer->Init();
234
235 //
236     AliGenMC::Init();
237 }
238
239 //____________________________________________________________
240 void AliGenParam::Generate()
241 {
242 //
243 // Generate 'npart' of light and heavy mesons (J/Psi, upsilon or phi, Pion,
244 // Kaons, Etas, Omegas) and Baryons (proton, antiprotons, neutrons and 
245 // antineutrons in the the desired theta, phi and momentum windows; 
246 // Gaussian smearing on the vertex is done if selected. 
247 // The decay of heavy mesons is done using lujet, 
248 //    and the childern particle are tracked by GEANT
249 // However, light mesons are directly tracked by GEANT 
250 // setting fForceDecay = nodecay (SetForceDecay(nodecay)) 
251 //
252 //
253 //  Reinitialize decayer
254   fDecayer->SetForceDecay(fForceDecay);
255   fDecayer->Init();
256
257 //
258   Float_t polar[3]= {0,0,0};  // Polarisation of the parent particle (for GEANT tracking)
259   Float_t origin0[3];         // Origin of the generated parent particle (for GEANT tracking)
260   Float_t pt, pl, ptot;       // Transverse, logitudinal and total momenta of the parent particle
261   Float_t phi, theta;         // Phi and theta spherical angles of the parent particle momentum
262   Float_t p[3], pc[3], 
263           och[3];             // Momentum, polarisation and origin of the children particles from lujet
264   Double_t ty, xmt;
265   Int_t nt, i, j;
266   Float_t  wgtp, wgtch;
267   Double_t dummy;
268   static TClonesArray *particles;
269   //
270   if(!particles) particles = new TClonesArray("TParticle",1000);
271   
272   TDatabasePDG *pDataBase = TDatabasePDG::Instance();
273   //
274   Float_t random[6];
275  
276 // Calculating vertex position per event
277   for (j=0;j<3;j++) origin0[j]=fOrigin[j];
278   if(fVertexSmear==kPerEvent) {
279       Vertex();
280       for (j=0;j<3;j++) origin0[j]=fVertex[j];
281   }
282   
283   Int_t ipa=0;
284   
285 // Generating fNpart particles
286   while (ipa<fNpart) {
287       while(1) {
288 //
289 // particle type 
290           Int_t iPart = fIpParaFunc(fRandom);
291           fChildWeight=(fDecayer->GetPartialBranchingRatio(iPart))*fParentWeight;          
292           TParticlePDG *particle = pDataBase->GetParticle(iPart);
293           Float_t am = particle->Mass();
294           
295           Rndm(random,2);
296 //
297 // phi
298           phi=fPhiMin+random[0]*(fPhiMax-fPhiMin);
299 //
300 // y
301           ty = TMath::TanH(fYPara->GetRandom());
302 //
303 // pT
304           if (fAnalog == kAnalog) {
305               pt=fPtPara->GetRandom();
306               wgtp=fParentWeight;
307               wgtch=fChildWeight;
308           } else {
309               pt=fPtMin+random[1]*(fPtMax-fPtMin);
310               Double_t ptd=pt;
311               wgtp=fParentWeight*fPtParaFunc(& ptd, &dummy);
312               wgtch=fChildWeight*fPtParaFunc(& ptd, &dummy);
313           }
314           xmt=sqrt(pt*pt+am*am);
315           if (TMath::Abs(ty)==1.) {
316               ty=0.;
317               Fatal("AliGenParam", 
318                     "Division by 0: Please check you rapidity range !");
319           }
320           
321           pl=xmt*ty/sqrt(1.-ty*ty);
322           theta=TMath::ATan2(pt,pl);
323 // Cut on theta
324           if(theta<fThetaMin || theta>fThetaMax) continue;
325           ptot=TMath::Sqrt(pt*pt+pl*pl);
326 // Cut on momentum
327           if(ptot<fPMin || ptot>fPMax) continue;
328 //
329           p[0]=pt*TMath::Cos(phi);
330           p[1]=pt*TMath::Sin(phi);
331           p[2]=pl;
332           if(fVertexSmear==kPerTrack) {
333               Rndm(random,6);
334               for (j=0;j<3;j++) {
335                   origin0[j]=
336                       fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
337                       TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
338               }
339           }
340           
341 // Looking at fForceDecay : 
342 // if fForceDecay != none Primary particle decays using 
343 // AliPythia and children are tracked by GEANT
344 //
345 // if fForceDecay == none Primary particle is tracked by GEANT 
346 // (In the latest, make sure that GEANT actually does all the decays you want)    
347 //
348
349           if (fForceDecay != kNoDecay) {
350 // Using lujet to decay particle
351               Float_t energy=TMath::Sqrt(ptot*ptot+am*am);
352               TLorentzVector pmom(p[0], p[1], p[2], energy);
353               fDecayer->Decay(iPart,&pmom);
354 //
355 // select decay particles
356               Int_t np=fDecayer->ImportParticles(particles);
357
358               //  Selecting  GeometryAcceptance for particles fPdgCodeParticleforAcceptanceCut;
359               if (fGeometryAcceptance) 
360                 if (!CheckAcceptanceGeometry(np,particles)) continue;
361               Int_t ncsel=0;
362               Int_t* pFlag      = new Int_t[np];
363               Int_t* pParent    = new Int_t[np];
364               Int_t* pSelected  = new Int_t[np];
365               Int_t* trackIt    = new Int_t[np];
366
367               for (i=0; i<np; i++) {
368                   pFlag[i]     =  0;
369                   pSelected[i] =  0;
370                   pParent[i]   = -1;
371               }
372               
373               if (np >1) {
374                   TParticle* iparticle =  (TParticle *) particles->At(0);
375                   Int_t ipF, ipL;
376                   for (i = 1; i<np ; i++) {
377                       trackIt[i] = 1;
378                       iparticle = (TParticle *) particles->At(i);
379                       Int_t kf = iparticle->GetPdgCode();
380                       Int_t ks = iparticle->GetStatusCode();
381 // flagged particle
382
383                       if (pFlag[i] == 1) {
384                           ipF = iparticle->GetFirstDaughter();
385                           ipL = iparticle->GetLastDaughter();   
386                           if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
387                           continue;
388                       }
389
390 // flag decay products of particles with long life-time (c tau > .3 mum)                      
391                       
392                       if (ks != 1) { 
393 //                        TParticlePDG *particle = pDataBase->GetParticle(kf);
394                           
395                           Double_t lifeTime = fDecayer->GetLifetime(kf);
396 //                        Double_t mass     = particle->Mass();
397 //                        Double_t width    = particle->Width();
398                           if (lifeTime > (Double_t) fMaxLifeTime) {
399                               ipF = iparticle->GetFirstDaughter();
400                               ipL = iparticle->GetLastDaughter();       
401                               if (ipF > 0) for (j=ipF-1; j<ipL; j++) pFlag[j]=1;
402                           } else{
403                               trackIt[i]     = 0;
404                               pSelected[i]   = 1;
405                           }
406                       } // ks==1 ?
407 //
408 // children
409                       
410                       if (ChildSelected(TMath::Abs(kf)) || fForceDecay == kAll && trackIt[i])
411                       {
412                           if (fCutOnChild) {
413                               pc[0]=iparticle->Px();
414                               pc[1]=iparticle->Py();
415                               pc[2]=iparticle->Pz();
416                               Bool_t  childok = KinematicSelection(iparticle, 1);
417                               if(childok) {
418                                   pSelected[i]  = 1;
419                                   ncsel++;
420                               } else {
421                                   ncsel=-1;
422                                   break;
423                               } // child kine cuts
424                           } else {
425                               pSelected[i]  = 1;
426                               ncsel++;
427                           } // if child selection
428                       } // select muon
429                   } // decay particle loop
430               } // if decay products
431               
432               Int_t iparent;
433               if ((fCutOnChild && ncsel >0) || !fCutOnChild){
434                   ipa++;
435 //
436 // Parent
437                   PushTrack(0, -1, iPart, p, origin0, polar, 0, kPPrimary, nt, wgtp);
438                   pParent[0] = nt;
439                   KeepTrack(nt); 
440 //
441 // Decay Products
442 //                
443                   for (i = 1; i < np; i++) {
444                       if (pSelected[i]) {
445                           TParticle* iparticle = (TParticle *) particles->At(i);
446                           Int_t kf  = iparticle->GetPdgCode();
447                           Int_t ipa = iparticle->GetFirstMother()-1;
448                           
449                           och[0] = origin0[0]+iparticle->Vx()/10;
450                           och[1] = origin0[1]+iparticle->Vy()/10;
451                           och[2] = origin0[2]+iparticle->Vz()/10;
452                           pc[0]  = iparticle->Px();
453                           pc[1]  = iparticle->Py();
454                           pc[2]  = iparticle->Pz();
455                           
456                           if (ipa > -1) {
457                               iparent = pParent[ipa];
458                           } else {
459                               iparent = -1;
460                           }
461                          
462                           PushTrack(fTrackIt*trackIt[i], iparent, kf,
463                                            pc, och, polar,
464                                            0, kPDecay, nt, wgtch);
465                           pParent[i] = nt;
466                           KeepTrack(nt); 
467                       } // Selected
468                   } // Particle loop 
469               }  // Decays by Lujet
470               particles->Clear();
471               if (pFlag)      delete[] pFlag;
472               if (pParent)    delete[] pParent;
473               if (pSelected)  delete[] pSelected;          
474               if (trackIt)    delete[] trackIt;
475           } // kinematic selection
476           else  // nodecay option, so parent will be tracked by GEANT (pions, kaons, eta, omegas, baryons)
477           {
478             gAlice->GetMCApp()->
479                 PushTrack(fTrackIt,-1,iPart,p,origin0,polar,0,kPPrimary,nt,wgtp);
480             ipa++; 
481           }
482           break;
483     } // while
484   } // event loop
485   SetHighWaterMark(nt);
486 }
487 //____________________________________________________________________________________
488 Float_t AliGenParam::GetRelativeArea(Float_t ptMin, Float_t ptMax, Float_t yMin, Float_t yMax, Float_t phiMin, Float_t phiMax)
489 {
490 //
491 // Normalisation for selected kinematic region
492 //
493   Float_t ratio =  
494     fPtPara->Integral(ptMin,ptMax,(Double_t *)0,1.e-6) / fPtPara->Integral( fPtPara->GetXmin(), fPtPara->GetXmax(),(Double_t *)0,1.e-6) *
495     fYPara->Integral(yMin,yMax,(Double_t *)0,1.e-6)/fYPara->Integral(fYPara->GetXmin(),fYPara->GetXmax(),(Double_t *)0,1.e-6)   *
496     (phiMax-phiMin)/360.;
497   return TMath::Abs(ratio);
498 }
499
500 //____________________________________________________________________________________
501
502 void AliGenParam::Draw( const char * /*opt*/)
503 {
504     //
505     // Draw the pT and y Distributions
506     //
507      TCanvas *c0 = new TCanvas("c0","Canvas 0",400,10,600,700);
508      c0->Divide(2,1);
509      c0->cd(1);
510      fPtPara->Draw();
511      fPtPara->GetHistogram()->SetXTitle("p_{T} (GeV)");     
512      c0->cd(2);
513      fYPara->Draw();
514      fYPara->GetHistogram()->SetXTitle("y");     
515 }
516
517
518
519