1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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8 * documentation strictly for non-commercial purposes is hereby granted *
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14 **************************************************************************/
18 Revision 1.20 2003/01/28 15:29:07 morsch
19 Spelling in name corrected.
21 Revision 1.19 2003/01/14 10:50:18 alibrary
22 Cleanup of STEER coding conventions
24 Revision 1.18 2002/12/11 11:58:11 morsch
25 Bug in formula for pi0 energy for decay corrected.
27 Revision 1.17 2002/12/10 17:44:57 morsch
28 Correct mother child relation for pi0.
30 Revision 1.16 2002/11/28 11:46:15 morsch
31 Don't track pi0 if already decayed.
33 Revision 1.15 2002/11/28 11:38:53 morsch
36 Revision 1.14 2002/11/26 17:12:36 morsch
37 Decay pi0 if requested.
39 Revision 1.13 2002/10/14 14:55:35 hristov
40 Merging the VirtualMC branch to the main development branch (HEAD)
42 Revision 1.11.4.1 2002/07/24 08:56:28 alibrary
43 Updating EVGEN on TVirtulaMC
45 Revision 1.12 2002/06/19 06:56:34 hristov
48 Revision 1.11 2002/03/20 10:21:13 hristov
49 Set fPtMax to 15 GeV in order to avoid some numerical problems
51 Revision 1.10 2001/10/15 16:44:46 morsch
52 - Possibility for vertex distribution truncation.
53 - Write mc header with vertex position.
55 Revision 1.9 2001/07/27 17:09:36 morsch
56 Use local SetTrack, KeepTrack and SetHighWaterMark methods
57 to delegate either to local stack or to stack owned by AliRun.
58 (Piotr Skowronski, A.M.)
60 Revision 1.8 2001/07/20 11:03:58 morsch
61 Issue warning message if used outside allowed eta range (-8 to 8).
63 Revision 1.7 2001/07/17 12:41:01 morsch
64 - Calculation of fraction of event corresponding to selected pt-range corrected
66 - Parent weight corrected.
68 Revision 1.6 2001/05/16 14:57:10 alibrary
69 New files for folders and Stack
71 Revision 1.5 2000/12/21 16:24:06 morsch
72 Coding convention clean-up
74 Revision 1.4 2000/11/30 07:12:50 alibrary
75 Introducing new Rndm and QA classes
77 Revision 1.3 2000/10/02 21:28:06 fca
78 Removal of useless dependecies via forward declarations
80 Revision 1.2 2000/07/11 18:24:55 fca
81 Coding convention corrections + few minor bug fixes
83 Revision 1.1 2000/06/09 20:20:30 morsch
84 Same class as previously in AliSimpleGen.cxx
85 All coding rule violations except RS3 corrected (AM)
89 // Parameterisation of pi and K, eta and pt distributions
90 // used for the ALICE TDRs.
91 // eta: according to HIJING (shadowing + quenching)
92 // pT : according to CDF measurement at 1.8 TeV
93 // Author: andreas.morsch@cern.ch
98 <img src="picts/AliGeneratorClass.gif">
101 <font size=+2 color=red>
102 <p>The responsible person for this module is
103 <a href="mailto:andreas.morsch@cern.ch">Andreas Morsch</a>.
109 ///////////////////////////////////////////////////////////////////
112 #include <TClonesArray.h>
113 #include <TDatabasePDG.h>
115 #include <TParticle.h>
116 #include <TPDGCode.h>
118 #include "AliConst.h"
119 #include "AliDecayer.h"
120 #include "AliGenEventHeader.h"
121 #include "AliGenHIJINGpara.h"
124 ClassImp(AliGenHIJINGpara)
126 AliGenHIJINGpara::AliGenHIJINGpara(const AliGenHIJINGpara & para)
131 //_____________________________________________________________________________
132 static Double_t ptpi(Double_t *px, Double_t *)
135 // PT-PARAMETERIZATION CDF, PRL 61(88) 1819
136 // POWER LAW FOR PT > 500 MEV
137 // MT SCALING BELOW (T=160 MEV)
139 const Double_t kp0 = 1.3;
140 const Double_t kxn = 8.28;
141 const Double_t kxlim=0.5;
142 const Double_t kt=0.160;
143 const Double_t kxmpi=0.139;
144 const Double_t kb=1.;
145 Double_t y, y1, xmpi2, ynorm, a;
148 y1=TMath::Power(kp0/(kp0+kxlim),kxn);
150 ynorm=kb*(TMath::Exp(-sqrt(kxlim*kxlim+xmpi2)/kt));
153 y=a*TMath::Power(kp0/(kp0+x),kxn);
155 y=kb*TMath::Exp(-sqrt(x*x+xmpi2)/kt);
159 //_____________________________________________________________________________
160 static Double_t ptscal(Double_t pt, Int_t np)
162 // SCALING EN MASSE PAR RAPPORT A PTPI
163 // MASS PI,K,ETA,RHO,OMEGA,ETA',PHI
164 const Double_t khm[10] = {.13957,.493,.5488,.769,.7826,.958,1.02,0,0,0};
165 // VALUE MESON/PI AT 5 GEV
166 const Double_t kfmax[10]={1.,0.3,0.55,1.0,1.0,1.0,1.0,0,0,0};
168 Double_t f5=TMath::Power(((
169 sqrt(100.018215)+2.)/(sqrt(100.+khm[np]*khm[np])+2.0)),12.3);
170 Double_t fmax2=f5/kfmax[np];
172 Double_t ptpion=100.*ptpi(&pt, (Double_t*) 0);
173 Double_t fmtscal=TMath::Power(((
174 sqrt(pt*pt+0.018215)+2.)/ (sqrt(pt*pt+khm[np]*khm[np])+2.0)),12.3)/
176 return fmtscal*ptpion;
179 //_____________________________________________________________________________
180 static Double_t ptka( Double_t *px, Double_t *)
183 // pt parametrisation for k
185 return ptscal(*px,2);
189 //_____________________________________________________________________________
190 static Double_t etapic( Double_t *py, Double_t *)
193 // eta parametrisation for pi
195 const Double_t ka1 = 4913.;
196 const Double_t ka2 = 1819.;
197 const Double_t keta1 = 0.22;
198 const Double_t keta2 = 3.66;
199 const Double_t kdeta1 = 1.47;
200 const Double_t kdeta2 = 1.51;
201 Double_t y=TMath::Abs(*py);
203 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
204 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
205 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
208 //_____________________________________________________________________________
209 static Double_t etakac( Double_t *py, Double_t *)
212 // eta parametrisation for ka
214 const Double_t ka1 = 497.6;
215 const Double_t ka2 = 215.6;
216 const Double_t keta1 = 0.79;
217 const Double_t keta2 = 4.09;
218 const Double_t kdeta1 = 1.54;
219 const Double_t kdeta2 = 1.40;
220 Double_t y=TMath::Abs(*py);
222 Double_t ex1 = (y-keta1)*(y-keta1)/(2*kdeta1*kdeta1);
223 Double_t ex2 = (y-keta2)*(y-keta2)/(2*kdeta2*kdeta2);
224 return ka1*TMath::Exp(-ex1)+ka2*TMath::Exp(-ex2);
227 //_____________________________________________________________________________
228 AliGenHIJINGpara::AliGenHIJINGpara()
232 // Default constructor
245 //_____________________________________________________________________________
246 AliGenHIJINGpara::AliGenHIJINGpara(Int_t npart)
250 // Standard constructor
253 fTitle="HIJING Parametrisation Particle Generator";
265 //_____________________________________________________________________________
266 AliGenHIJINGpara::~AliGenHIJINGpara()
269 // Standard destructor
277 //_____________________________________________________________________________
278 void AliGenHIJINGpara::Init()
281 // Initialise the HIJING parametrisation
283 Float_t etaMin =-TMath::Log(TMath::Tan(
284 TMath::Min((Double_t)fThetaMax/2,TMath::Pi()/2-1.e-10)));
285 Float_t etaMax = -TMath::Log(TMath::Tan(
286 TMath::Max((Double_t)fThetaMin/2,1.e-10)));
287 fPtpi = new TF1("ptpi",&ptpi,0,20,0);
288 fPtka = new TF1("ptka",&ptka,0,20,0);
289 fETApic = new TF1("etapic",&etapic,etaMin,etaMax,0);
290 fETAkac = new TF1("etakac",&etakac,etaMin,etaMax,0);
292 TF1 etaPic0("etapic",&etapic,-7,7,0);
293 TF1 etaKac0("etakac",&etakac,-7,7,0);
295 TF1 ptPic0("ptpi",&ptpi,0.,15.,0);
296 TF1 ptKac0("ptka",&ptka,0.,15.,0);
298 Float_t intETApi = etaPic0.Integral(-0.5, 0.5);
299 Float_t intETAka = etaKac0.Integral(-0.5, 0.5);
300 Float_t scalePi = 7316/(intETApi/1.5);
301 Float_t scaleKa = 684/(intETAka/2.0);
303 // Fraction of events corresponding to the selected pt-range
304 Float_t intPt = (0.877*ptPic0.Integral(0, 15)+
305 0.123*ptKac0.Integral(0, 15));
306 Float_t intPtSel = (0.877*ptPic0.Integral(fPtMin, fPtMax)+
307 0.123*ptKac0.Integral(fPtMin, fPtMax));
308 Float_t ptFrac = intPtSel/intPt;
310 // Fraction of events corresponding to the selected eta-range
311 Float_t intETASel = (scalePi*etaPic0.Integral(etaMin, etaMax)+
312 scaleKa*etaKac0.Integral(etaMin, etaMax));
313 // Fraction of events corresponding to the selected phi-range
314 Float_t phiFrac = (fPhiMax-fPhiMin)/2/TMath::Pi();
316 fParentWeight = Float_t(fNpart)/(intETASel*ptFrac*phiFrac);
318 printf("%s: The number of particles in the selected kinematic region corresponds to %f percent of a full event\n ",
319 ClassName(),100.*fParentWeight);
321 // Issue warning message if etaMin or etaMax are outside the alowed range
322 // of the parametrization
323 if (etaMin < -8.001 || etaMax > 8.001) {
324 printf("\n \n WARNING FROM AliGenHIJINGPara !");
325 printf("\n YOU ARE USING THE PARAMETERISATION OUTSIDE ");
326 printf("\n THE ALLOWED PSEUDORAPIDITY RANGE (-8. - 8.)");
327 printf("\n YOUR LIMITS: %f %f \n \n ", etaMin, etaMax);
331 if (fPi0Decays && gMC)
332 fDecayer = gMC->GetDecayer();
336 //_____________________________________________________________________________
337 void AliGenHIJINGpara::Generate()
340 // Generate one trigger
344 const Float_t kRaKpic=0.14;
345 const Float_t kBorne=1/(1+kRaKpic);
346 Float_t polar[3]= {0,0,0};
348 const Int_t kPions[3] = {kPi0, kPiPlus, kPiMinus};
349 const Int_t kKaons[4] = {kK0Long, kK0Short, kKPlus, kKMinus};
352 Float_t pt, pl, ptot;
362 for (j=0;j<3;j++) origin[j]=fOrigin[j];
364 if(fVertexSmear == kPerEvent) {
367 while(TMath::Abs(dv[2]) > fCutVertexZ*fOsigma[2]) {
369 for (j=0; j < 3; j++) {
370 dv[j] = fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
371 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
374 for (j=0; j < 3; j++) origin[j] += dv[j];
378 eventVertex[0] = origin[0];
379 eventVertex[1] = origin[1];
380 eventVertex[2] = origin[2];
382 for(i=0;i<fNpart;i++) {
385 if(random[0]<kBorne) {
386 part=kPions[Int_t (random[1]*3)];
390 part=kKaons[Int_t (random[1]*4)];
394 phi=fPhiMin+random[2]*(fPhiMax-fPhiMin);
395 theta=2*TMath::ATan(TMath::Exp(-etaf->GetRandom()));
396 if(theta<fThetaMin || theta>fThetaMax) continue;
398 pl=pt/TMath::Tan(theta);
399 ptot=TMath::Sqrt(pt*pt+pl*pl);
400 if(ptot<fPMin || ptot>fPMax) continue;
401 p[0]=pt*TMath::Cos(phi);
402 p[1]=pt*TMath::Sin(phi);
404 if(fVertexSmear==kPerTrack) {
407 origin[j]=fOrigin[j]+fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
408 TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
411 if (part == kPi0 && fPi0Decays){
413 // Decay pi0 if requested
414 SetTrack(0,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
418 SetTrack(fTrackIt,-1,part,p,origin,polar,0,kPPrimary,fNt,fParentWeight);
424 SetHighWaterMark(fNt);
429 AliGenEventHeader* header = new AliGenEventHeader("HIJINGparam");
431 header->SetPrimaryVertex(eventVertex);
432 gAlice->SetGenEventHeader(header);
435 AliGenHIJINGpara& AliGenHIJINGpara::operator=(const AliGenHIJINGpara& rhs)
437 // Assignment operator
441 void AliGenHIJINGpara::SetPtRange(Float_t ptmin, Float_t ptmax) {
442 AliGenerator::SetPtRange(ptmin, ptmax);
445 void AliGenHIJINGpara::DecayPi0(Float_t* orig, Float_t * p)
449 // and put decay products on the stack
451 static TClonesArray *particles;
452 if(!particles) particles = new TClonesArray("TParticle",1000);
454 const Float_t kMass = TDatabasePDG::Instance()->GetParticle(kPi0)->Mass();
455 Float_t e = TMath::Sqrt(p[0] * p[0] + p[1] * p[1] + p[2] * p[2]+ kMass * kMass);
458 TLorentzVector pmom(p[0], p[1], p[2], e);
459 fDecayer->Decay(kPi0, &pmom);
462 // Put decay particles on the stack
464 Float_t polar[3] = {0., 0., 0.};
465 Int_t np = fDecayer->ImportParticles(particles);
467 for (Int_t i = 1; i < np; i++)
469 TParticle* iParticle = (TParticle *) particles->At(i);
470 p[0] = iParticle->Px();
471 p[1] = iParticle->Py();
472 p[2] = iParticle->Pz();
473 Int_t part = iParticle->GetPdgCode();
475 SetTrack(fTrackIt, fNt, part, p, orig, polar, 0, kPDecay, nt, fParentWeight);